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3381 lines
128 KiB
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3381 lines
128 KiB
Plaintext
@setfilename LNEWS
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@section New Features in the Lisp Language
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@end itemize
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@itemize @bullet
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@item
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The new function @code{delete} is a traditional Lisp function. It takes
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two arguments, @var{elt} and @var{list}, and deletes from @var{list} any
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elements that are equal to @var{elt}. It uses the function @code{equal}
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to compare elements with @var{elt}.
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@item
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The new function @code{member} is a traditional Lisp function. It takes
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two arguments, @var{elt} and @var{list}, and finds the first element of
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@var{list} that is equal to @var{elt}. It uses the function
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@code{equal} to compare each list element with @var{elt}.
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The value is a sublist of @var{list}, whose first element is the one
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that was found. If no matching element is found, the value is
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@code{nil}.
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@ignore @c Seems not to be true, from looking at the code.
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@item
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The function @code{equal} is now more robust: it does not crash due to
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circular list structure.
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@end ignore
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@item
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The new function @code{indirect-function} finds the effective function
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definition of an object called as a function. If the object is a
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symbol, @code{indirect-function} looks in the function definition of the
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symbol. It keeps doing this until it finds something that is not a
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symbol.
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@item
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There are new escape sequences for use in character and string
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constants. The escape sequence @samp{\a} is equivalent to @samp{\C-g},
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the @sc{ASCII} @sc{BEL} character (code 7). The escape sequence
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@samp{\x} followed by a hexidecimal number represents the character
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whose @sc{ASCII} code is that number. There is no limit on the number
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of digits in the hexidecimal value.
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@item
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The function @code{read} when reading from a buffer now does not skip a
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terminator character that terminates a symbol. It leaves that character
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to be read (or just skipped, if it is whitespace) next time.
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@item
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When you use a function @var{function} as the input stream for
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@code{read}, it is usually called with no arguments, and should return
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the next character. In Emacs 19, sometimes @var{function} is called
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with one argument (always a character). When that happens,
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@var{function} should save the argument and arrange to return it when
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called next time.
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@item
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@code{random} with integer argument @var{n} returns a random number
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between 0 and @var{n}@minus{}1.
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@item
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The functions @code{documentation} and @code{documentation-property} now
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take an additional optional argument which, if non-@code{nil}, says to
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refrain from calling @code{substitute-command-keys}. This way, you get
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the exact text of the documentation string as written, without the usual
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substitutions. Make sure to call @code{substitute-command-keys}
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yourself if you decide to display the string.
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@ignore
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@item
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The new function @code{invocation-name} returns as a string the program
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name that was used to run Emacs, with any directory names discarded.
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@c ??? This hasn't been written yet. ???
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@end ignore
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@item
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The new function @code{map-y-or-n-p} makes it convenient to ask a series
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of similar questions. The arguments are @var{prompter}, @var{actor},
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@var{list}, and optional @var{help}.
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The value of @var{list} is a list of objects, or a function of no
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arguments to return either the next object or @code{nil} meaning there
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are no more.
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The argument @var{prompter} specifies how to ask each question. If
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@var{prompter} is a string, the question text is computed like this:
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@example
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(format @var{prompter} @var{object})
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@end example
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@noindent
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where @var{object} is the next object to ask about.
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If not a string, @var{prompter} should be a function of one argument
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(the next object to ask about) and should return the question text.
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The argument @var{actor} should be a function of one argument, which is
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called with each object that the user says yes for. Its argument is
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always one object from @var{list}.
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If @var{help} is given, it is a list @code{(@var{object} @var{objects}
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@var{action})}, where @var{object} is a string containing a singular
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noun that describes the objects conceptually being acted on;
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@var{objects} is the corresponding plural noun and @var{action} is a
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transitive verb describing @var{actor}. The default is @code{("object"
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"objects" "act on")}.
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Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or
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@key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip
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that object; @kbd{!} to act on all following objects; @key{ESC} or
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@kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on
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the current object and then exit; or @kbd{C-h} to get help.
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@code{map-y-or-n-p} returns the number of objects acted on.
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@item
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You can now ``set'' environment variables with the @code{setenv}
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command. This works by setting the variable @code{process-environment},
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which @code{getenv} now examines in preference to the environment Emacs
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received from its parent.
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@end itemize
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@section New Features for Loading Libraries
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You can now arrange to run a hook if a particular Lisp library is
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loaded.
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The variable @code{after-load-alist} is an alist of expressions to be
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evalled when particular files are loaded. Each element looks like
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@code{(@var{filename} @var{forms}@dots{})}.
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When @code{load} is run and the file name argument equals
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@var{filename}, the @var{forms} in the corresponding element are
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executed at the end of loading. @var{filename} must match exactly!
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Normally @var{filename} is the name of a library, with no directory
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specified, since that is how @code{load} is normally called.
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An error in @var{forms} does not undo the load, but does prevent
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execution of the rest of the @var{forms}.
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The function @code{eval-after-load} provides a convenient way to add
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entries to the alist. Call it with two arguments, @var{file} and a
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form to execute.
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The function @code{autoload} now supports autoloading a keymap.
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Use @code{keymap} as the fourth argument if the autoloaded function
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will become a keymap when loaded.
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There is a new feature for specifying which functions in a library should
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be autoloaded by writing special ``magic'' comments in that library itself.
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Write @samp{;;;###autoload} on a line by itself before a function
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definition before the real definition of the function, in its
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autoloadable source file; then the command @kbd{M-x
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update-file-autoloads} automatically puts the @code{autoload} call into
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@file{loaddefs.el}.
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You can also put other kinds of forms into @file{loaddefs.el}, by
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writing @samp{;;;###autoload} followed on the same line by the form.
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@kbd{M-x update-file-autoloads} copies the form from that line.
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@section Compilation Features
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@itemize @bullet
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@item
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Inline functions.
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You can define an @dfn{inline function} with @code{defsubst}. Use
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@code{defsubst} just like @code{defun}, and it defines a function which
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you can call in all the usual ways. Whenever the function thus defined
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is used in compiled code, the compiler will open code it.
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You can get somewhat the same effects with a macro, but a macro has the
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limitation that you can use it only explicitly; a macro cannot be called
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with @code{apply}, @code{mapcar} and so on. Also, it takes some work to
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convert an ordinary function into a macro. To convert it into an inline
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function, simply replace @code{defun} with @code{defsubst}.
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Making a function inline makes explicit calls run faster. But it also
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has disadvantages. For one thing, it reduces flexibility; if you change
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the definition of the function, calls already inlined still use the old
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definition until you recompile them.
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Another disadvantage is that making a large function inline can increase
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the size of compiled code both in files and in memory. Since the
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advantages of inline functions are greatest for small functions, you
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generally should not make large functions inline.
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Inline functions can be used and open coded later on in the same file,
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following the definition, just like macros.
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@item
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The command @code{byte-compile-file} now offers to save any buffer
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visiting the file you are compiling.
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@item
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The new command @code{compile-defun} reads, compiles and executes the
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defun containing point. If you use this on a defun that is actually a
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function definition, the effect is to install a compiled version of
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that function.
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@item
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Whenever you load a Lisp file or library, you now receive a warning if
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the directory contains both a @samp{.el} file and a @samp{.elc} file,
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and the @samp{.el} file is newer. This typically indicates that someone
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has updated the Lisp code but forgotten to recompile it, so the changes
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do not take effect. The warning is a reminder to recompile.
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@item
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The special form @code{eval-when-compile} marks the forms it contains to
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be evaluated at compile time @emph{only}. At top-level, this is
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analogous to the Common Lisp idiom @code{(eval-when (compile)
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@dots{})}. Elsewhere, it is similar to the Common Lisp @samp{#.} reader
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macro (but not when interpreting).
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If you're thinking of using this feature, we recommend you consider whether
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@code{provide} and @code{require} might do the job as well.
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@item
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The special form @code{eval-and-compile} is similar to
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@code{eval-when-compile}, but the whole form is evaluated both at
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compile time and at run time.
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If you're thinking of using this feature, we recommend you consider
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whether @code{provide} and @code{require} might do the job as well.
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@item
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Emacs Lisp has a new data type for byte-code functions. This makes
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them faster to call, and also saves space. Internally, a byte-code
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function object is much like a vector; however, the evaluator handles
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this data type specially when it appears as a function to be called.
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The printed representation for a byte-code function object is like that
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for a vector, except that it starts with @samp{#} before the opening
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@samp{[}. A byte-code function object must have at least four elements;
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there is no maximum number, but only the first six elements are actually
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used. They are:
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@table @var
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@item arglist
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The list of argument symbols.
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@item byte-code
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The string containing the byte-code instructions.
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@item constants
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The vector of constants referenced by the byte code.
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@item stacksize
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The maximum stack size this function needs.
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@item docstring
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The documentation string (if any); otherwise, @code{nil}.
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@item interactive
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The interactive spec (if any). This can be a string or a Lisp
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expression. It is @code{nil} for a function that isn't interactive.
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@end table
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The predicate @code{byte-code-function-p} tests whether a given object
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is a byte-code function.
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You can create a byte-code function object in a Lisp program
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with the function @code{make-byte-code}. Its arguments are the elements
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to put in the byte-code function object.
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You should not try to come up with the elements for a byte-code function
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yourself, because if they are inconsistent, Emacs may crash when you
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call the function. Always leave it to the byte compiler to create these
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objects; it, we hope, always makes the elements consistent.
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@end itemize
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@section Floating Point Numbers
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You can now use floating point numbers in Emacs, if you define the macro
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@code{LISP_FLOAT_TYPE} when you compile Emacs.
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The printed representation for floating point numbers requires either a
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decimal point surrounded by digits, or an exponent, or both. For
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example, @samp{1500.0}, @samp{15e2}, @samp{15.0e2} and @samp{1.5e3} are
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four ways of writing a floating point number whose value is 1500.
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The existing predicate @code{numberp} now returns @code{t} if the
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argument is any kind of number---either integer or floating. The new
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predicates @code{integerp} and @code{floatp} check for specific types of
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numbers.
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You can do arithmetic on floating point numbers with the ordinary
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arithmetic functions, @code{+}, @code{-}, @code{*} and @code{/}. If you
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call one of these functions with both integers and floating point
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numbers among the arguments, the arithmetic is done in floating point.
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The same applies to the numeric comparison functions such as @code{=}
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and @code{<}. The remainder function @code{%} does not accept floating
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point arguments, and neither do the bitwise boolean operations such as
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@code{logand} or the shift functions such as @code{ash}.
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There is a new arithmetic function, @code{abs}, which returns the absolute
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value of its argument. It handles both integers and floating point
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numbers.
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To convert an integer to floating point, use the function @code{float}.
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There are four functions to convert floating point numbers to integers;
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they differ in how they round. @code{truncate} rounds toward 0,
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@code{floor} rounds down, @code{ceil} rounds up, and @code{round}
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produces the nearest integer.
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You can use @code{logb} to extract the binary exponent of a floating
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point number. More precisely, it is the logarithm base 2, rounded down
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to an integer.
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Emacs has several new mathematical functions that accept any kind of
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number as argument, but always return floating point numbers.
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@table @code
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@item cos
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@findex cos
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@itemx sin
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@findex sin
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@itemx tan
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@findex tan
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Trigonometric functions.
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@item acos
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@findex acos
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@itemx asin
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@findex asin
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@itemx atan
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@findex atan
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Inverse trigonometric functions.
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@item exp
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@findex exp
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The exponential function (power of @var{e}).
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@item log
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@findex log
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Logarithm base @var{e}.
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@item expm1
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@findex expm1
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Power of @var{e}, minus 1.
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@item log1p
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@findex log1p
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Add 1, then take the logarithm.
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@item log10
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@findex log10
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Logarithm base 10
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@item expt
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@findex expt
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Raise @var{x} to power @var{y}.
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@item sqrt
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@findex sqrt
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The square root function.
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@end table
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The new function @code{string-to-number} now parses a string containing
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either an integer or a floating point number, returning the number.
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The @code{format} function now handles the specifications @samp{%e},
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@samp{%f} and @samp{%g} for printing floating point numbers; likewise
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@code{message}.
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The new variable @code{float-output-format} controls how Lisp prints
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floating point numbers. Its value should be @code{nil} or a string.
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If it is a string, it should contain a @samp{%}-spec like those accepted
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by @code{printf} in C, but with some restrictions. It must start with
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the two characters @samp{%.}. After that comes an integer which is the
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precision specification, and then a letter which controls the format.
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The letters allowed are @samp{e}, @samp{f} and @samp{g}. Use @samp{e}
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for exponential notation (@samp{@var{dig}.@var{digits}e@var{expt}}).
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Use @samp{f} for decimal point notation
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(@samp{@var{digits}.@var{digits}}). Use @samp{g} to choose the shorter
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of those two formats for the number at hand.
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The precision in any of these cases is the number of digits following
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the decimal point. With @samp{f}, a precision of 0 means to omit the
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decimal point. 0 is not allowed with @samp{f} or @samp{g}.
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A value of @code{nil} means to use the format @samp{%.20g}.
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No matter what the value of @code{float-output-format}, printing ensures
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that the result fits the syntax rules for a floating point number. If
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it doesn't fit (for example, if it looks like an integer), it is
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modified to fit. By contrast, the @code{format} function formats
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floating point numbers without requiring the output to fit the
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syntax rules for floating point number.
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@section New Features for Printing And Formatting Output
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@itemize @bullet
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@item
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The @code{format} function has a new feature: @samp{%S}. This print
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spec prints any kind of Lisp object, even a string, using its Lisp
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printed representation.
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By contrast, @samp{%s} prints everything without quotation.
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@item
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@code{prin1-to-string} now takes an optional second argument which says
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not to print the Lisp quotation characters. (In other words, to use
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@code{princ} instead of @code{prin1}.)
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@item
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The new variable @code{print-level} specifies the maximum depth of list
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nesting to print before cutting off all deeper structure. A value of
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@code{nil} means no limit.
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@end itemize
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@section Changes in Basic Editing Functions
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@itemize @bullet
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@item
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There are two new primitives for putting text in the kill ring:
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@code{kill-new} and @code{kill-append}.
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The function @code{kill-new} adds a string to the front of the kill ring.
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Use @code{kill-append} to add a string to a previous kill. The second
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argument @var{before-p}, if non-@code{nil}, says to add the string at
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the beginning; otherwise, it goes at the end.
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Both of these functions apply @code{interprogram-cut-function} to the
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entire string of killed text that ends up at the beginning of the kill
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ring.
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@item
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The new function @code{current-kill} rotates the yanking pointer in the
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kill ring by @var{n} places, and returns the text at that place in the
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ring. If the optional second argument @var{do-not-move} is
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non-@code{nil}, it doesn't actually move the yanking point; it just
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returns the @var{n}th kill forward. If @var{n} is zero, indicating a
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request for the latest kill, @code{current-kill} calls
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@code{interprogram-paste-function} (documented below) before consulting
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the kill ring.
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All Emacs Lisp programs should either use @code{current-kill},
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@code{kill-new}, and @code{kill-append} to manipulate the kill ring, or
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be sure to call @code{interprogram-paste-function} and
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@code{interprogram-cut-function} as appropriate.
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@item
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The variables @code{interprogram-paste-function} and
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@code{interprogram-cut-function} exist so that you can provide functions
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to transfer killed text to and from other programs.
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@item
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The @code{kill-region} function can now be used in read-only buffers.
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It beeps, but adds the region to the kill ring without deleting it.
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@item
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The new function @code{compare-buffer-substrings} lets you compare two
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substrings of the same buffer or two different buffers. Its arguments
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look like this:
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@example
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(compare-buffer-substrings @var{buf1} @var{beg1} @var{end1} @var{buf2} @var{beg2} @var{end2})
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@end example
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The first three arguments specify one substring, giving a buffer and two
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positions within the buffer. The last three arguments specify the other
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substring in the same way.
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The value is negative if the first substring is less, positive if the
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first is greater, and zero if they are equal. The absolute value of
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the result is one plus the index of the first different characters.
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@item
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Overwrite mode treats tab and newline characters specially. You can now
|
|
turn off this special treatment by setting @code{overwrite-binary-mode}
|
|
to @code{t}.
|
|
|
|
@item
|
|
Once the mark ``exists'' in a buffer, it normally never ceases to
|
|
exist. However, it may become @dfn{inactive}. The variable
|
|
@code{mark-active}, which is always local in all buffers, indicates
|
|
whether the mark is active: non-@code{nil} means yes.
|
|
|
|
A command can request deactivation of the mark upon return to the editor
|
|
command loop by setting @code{deactivate-mark} to a non-@code{nil}
|
|
value. Transient Mark mode works by causing the buffer modification
|
|
primitives to set @code{deactivate-mark}.
|
|
|
|
The variables @code{activate-mark-hook} and @code{deactivate-mark-hook}
|
|
are normal hooks run, respectively, when the mark becomes active andwhen
|
|
it becomes inactive. The hook @code{activate-mark-hook} is also run at
|
|
the end of a command if the mark is active and the region may have
|
|
changed.
|
|
|
|
@item
|
|
The function @code{move-to-column} now accepts a second optional
|
|
argument @var{force}, in addition to @var{column}; if the requested
|
|
column @var{column} is in the middle of a tab character and @var{force}
|
|
is non-@code{nil}, @code{move-to-column} replaces the tab with the
|
|
appropriate sequence of spaces so that it can place point exactly at
|
|
@var{column}.
|
|
|
|
@item
|
|
The search functions when successful now return the value of point
|
|
rather than just @code{t}. This affects the functions
|
|
@code{search-forward}, @code{search-backward},
|
|
@code{word-search-forward}, @code{word-search-backward},
|
|
@code{re-search-forward}, and @code{re-search-backward}.
|
|
|
|
@item
|
|
When you do regular expression searching or matching, there is no longer
|
|
a limit to how many @samp{\(@dots{}\)} pairs you can get information
|
|
about with @code{match-beginning} and @code{match-end}. Also, these
|
|
parenthetical groupings may now be nested to any degree.
|
|
|
|
@item
|
|
The new special form @code{save-match-data} preserves the regular
|
|
expression match status. Usage: @code{(save-match-data
|
|
@var{body}@dots{})}.
|
|
|
|
@item
|
|
The function @code{translate-region} applies a translation table to the
|
|
characters in a part of the buffer. Invoke it as
|
|
@code{(translate-region @var{start} @var{end} @var{table})}; @var{start}
|
|
and @var{end} bound the region to translate.
|
|
|
|
The translation table @var{table} is a string; @code{(aref @var{table}
|
|
@var{ochar})} gives the translated character corresponding to
|
|
@var{ochar}. If the length of @var{table} is less than 256, any
|
|
characters with codes larger than the length of @var{table} are not
|
|
altered by the translation.
|
|
|
|
@code{translate-region} returns the number of characters which were
|
|
actually changed by the translation. This does not count characters
|
|
which were mapped into themselves in the translation table.
|
|
|
|
@item
|
|
There are two new hook variables that let you notice all changes in all
|
|
buffers (or in a particular buffer, if you make them buffer-local):
|
|
@code{before-change-function} and @code{after-change-function}.
|
|
|
|
If @code{before-change-function} is non-@code{nil}, then it is called
|
|
before any buffer modification. Its arguments are the beginning and end
|
|
of the region that is going to change, represented as integers. The
|
|
buffer that's about to change is always the current buffer.
|
|
|
|
If @code{after-change-function} is non-@code{nil}, then it is called
|
|
after any buffer modification. It takes three arguments: the beginning
|
|
and end of the region just changed, and the length of the text that
|
|
existed before the change. (To get the current length, subtract the
|
|
rrgion beginning from the region end.) All three arguments are
|
|
integers. The buffer that's about to change is always the current
|
|
buffer.
|
|
|
|
Both of these variables are temporarily bound to @code{nil} during the
|
|
time that either of these hooks is running. This means that if one of
|
|
these functions changes the buffer, that change won't run these
|
|
functions. If you do want hooks to be run recursively, write your hook
|
|
functions to bind these variables back to their usual values.
|
|
|
|
@item
|
|
The hook @code{first-change-hook} is run using @code{run-hooks} whenever
|
|
a buffer is changed that was previously in the unmodified state.
|
|
|
|
@item
|
|
The second argument to @code{insert-abbrev-table-description} is
|
|
now optional.
|
|
@end itemize
|
|
|
|
@section Text Properties
|
|
|
|
Each character in a buffer or a string can have a @dfn{text property
|
|
list}, much like the property list of a symbol. The properties belong
|
|
to a particular character at a particular place, such as, the letter
|
|
@samp{T} at the beginning of this sentence. Each property has a name,
|
|
which is usually a symbol, and an associated value, which can be any
|
|
Lisp object---just as for properties of symbols (@pxref{Property Lists}).
|
|
|
|
You can use the property @code{face-code} to control the font and
|
|
color of text. That is the only property name which currently has a
|
|
special meaning, but you can create properties of any name and examine
|
|
them later for your own purposes.
|
|
|
|
Copying text between strings and buffers preserves the properties
|
|
along with the characters; this includes such diverse functions as
|
|
@code{substring}, @code{insert}, and @code{buffer-substring}.
|
|
|
|
Since text properties are considered part of the buffer contents,
|
|
changing properties in a buffer ``modifies'' the buffer, and you can
|
|
also undo such changes.
|
|
|
|
Strings with text properties have a special printed representation
|
|
which describes all the properties. This representation is also the
|
|
read syntax for such a string. It looks like this:
|
|
|
|
@example
|
|
#("@var{characters}" @var{property-data}...)
|
|
@end example
|
|
|
|
@noindent
|
|
where @var{property-data} is zero or more elements in groups of three as
|
|
follows:
|
|
|
|
@example
|
|
@var{beg} @var{end} @var{plist}
|
|
@end example
|
|
|
|
@noindent
|
|
The elements @var{beg} and @var{end} are integers, and together specify
|
|
a portion of the string; @var{plist} is the property list for that
|
|
portion.
|
|
|
|
@subsection Examining Text Properties
|
|
|
|
The simplest way to examine text properties is to ask for the value of
|
|
a particular property of a particular character. For that, use
|
|
@code{get-text-property}. Use @code{text-properties-at} to get the
|
|
entire property list of a character. @xref{Property Search}, for
|
|
functions to examine the properties of a number of characters at once.
|
|
|
|
@code{(get-text-property @var{pos} @var{prop} @var{object})} returns the
|
|
@var{prop} property of the character after @var{pos} in @var{object} (a
|
|
buffer or string). The argument @var{object} is optional and defaults
|
|
to the current buffer.
|
|
|
|
@code{(text-properties-at @var{pos} @var{object})} returns the entire
|
|
property list of the character after @var{pos} in the string or buffer
|
|
@var{object} (which defaults to the current buffer).
|
|
|
|
@subsection Changing Text Properties
|
|
|
|
There are three primitives for changing properties of a specified
|
|
range of text:
|
|
|
|
@table @code
|
|
@item add-text-properties
|
|
This function puts on specified properties, leaving other existing
|
|
properties unaltered.
|
|
|
|
@item put-text-property
|
|
This function puts on a single specified property, leaving others
|
|
unaltered.
|
|
|
|
@item remove-text-properties
|
|
This function removes specified properties, leaving other
|
|
properties unaltered.
|
|
|
|
@item set-text-properties
|
|
This function replaces the entire property list, leaving no vessage of
|
|
the properties that that text used to have.
|
|
@end table
|
|
|
|
All these functions take four arguments: @var{start}, @var{end},
|
|
@var{props}, and @var{object}. The last argument is optional and
|
|
defaults to the current buffer. The argument @var{props} has the form
|
|
of a property list.
|
|
|
|
@subsection Property Search Functions
|
|
|
|
In typical use of text properties, most of the time several or many
|
|
consecutive characters have the same value for a property. Rather than
|
|
writing your programs to examine characters one by one, it is much
|
|
faster to process chunks of text that have the same property value.
|
|
|
|
The functions @code{next-property-change} and
|
|
@code{previous-property-change} scan forward or backward from position
|
|
@var{pos} in @var{object}, looking for a change in any property between
|
|
two characters scanned. They returns the position between those two
|
|
characters, or @code{nil} if no change is found.
|
|
|
|
The functions @code{next-single-property-change} and
|
|
@code{previous-single-property-change} are similar except that you
|
|
specify a particular property and they look for changes in the value of
|
|
that property only. The property is the second argument, and
|
|
@var{object} is third.
|
|
|
|
@subsection Special Properties
|
|
|
|
If a character has a @code{category} property, we call it the
|
|
@dfn{category} of the character. It should be a symbol. The properties
|
|
of the symbol serve as defaults for the properties of the character.
|
|
|
|
You can use the property @code{face-code} to control the font and
|
|
color of text. That is the only property name which currently has a
|
|
special meaning, but you can create properties of any name and examine
|
|
them later for your own purposes.
|
|
about face codes.
|
|
|
|
You can specify a different keymap for a portion of the text by means
|
|
of a @code{local-map} property. The property's value, for the character
|
|
after point, replaces the buffer's local map.
|
|
|
|
If a character has the property @code{read-only}, then modifying that
|
|
character is not allowed. Any command that would do so gets an error.
|
|
|
|
If a character has the property @code{modification-hooks}, then its
|
|
value should be a list of functions; modifying that character calls all
|
|
of those functions. Each function receives two arguments: the beginning
|
|
and end of the part of the buffer being modified. Note that if a
|
|
particular modification hook function appears on several characters
|
|
being modified by a single primitive, you can't predict how many times
|
|
the function will be called.
|
|
|
|
Insertion of text does not, strictly speaking, change any existing
|
|
character, so there is a special rule for insertion. It compares the
|
|
@code{read-only} properties of the two surrounding characters; if they
|
|
are @code{eq}, then the insertion is not allowed. Assuming insertion is
|
|
allowed, it then gets the @code{modification-hooks} properties of those
|
|
characters and calls all the functions in each of them. (If a function
|
|
appears on both characters, it may be called once or twice.)
|
|
|
|
The special properties @code{point-entered} and @code{point-left}
|
|
record hook functions that report motion of point. Each time point
|
|
moves, Emacs compares these two property values:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
the @code{point-left} property of the character after the old location,
|
|
and
|
|
@item
|
|
the @code{point-entered} property of the character after the new
|
|
location.
|
|
@end itemize
|
|
|
|
@noindent
|
|
If these two values differ, each of them is called (if not @code{nil})
|
|
with two arguments: the old value of point, and the new one.
|
|
|
|
The same comparison is made for the characters before the old and new
|
|
locations. The result may be to execute two @code{point-left} functions
|
|
(which may be the same function) and/or two @code{point-entered}
|
|
functions (which may be the same function). The @code{point-left}
|
|
functions are always called before the @code{point-entered} functions.
|
|
|
|
A primitive function may examine characters at various positions
|
|
without moving point to those positions. Only an actual change in the
|
|
value of point runs these hook functions.
|
|
|
|
@section New Features for Files
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The new function @code{file-accessible-directory-p} tells you whether
|
|
you can open files in a particular directory. Specify as an argument
|
|
either a directory name or a file name which names a directory file.
|
|
The function returns @code{t} if you can open existing files in that
|
|
directory.
|
|
|
|
@item
|
|
The new function @code{file-executable-p} returns @code{t} if its
|
|
argument is the name of a file you have permission to execute.
|
|
|
|
@item
|
|
The function @code{file-truename} returns the ``true name'' of a
|
|
specified file. This is the name that you get by following symbolic
|
|
links until none remain. The argument must be an absolute file name.
|
|
|
|
@item
|
|
New functions @code{make-directory} and @code{delete-directory} create and
|
|
delete directories. They both take one argument, which is the name of
|
|
the directory as a file.
|
|
|
|
@item
|
|
The function @code{read-file-name} now takes an additional argument
|
|
which specifies an initial file name. If you specify this argument,
|
|
@code{read-file-name} inserts it along with the directory name. It puts
|
|
the cursor between the directory and the initial file name.
|
|
|
|
The user can then use the initial file name unchanged, modify it, or
|
|
simply kill it with @kbd{C-k}.
|
|
|
|
If the variable @code{insert-default-directory} is @code{nil}, then the
|
|
default directory is not inserted, and the new argument is ignored.
|
|
|
|
@item
|
|
The function @code{file-relative-name} does the inverse of
|
|
expansion---it tries to return a relative name which is equivalent to
|
|
@var{filename} when interpreted relative to @var{directory}. (If such a
|
|
relative name would be longer than the absolute name, it returns the
|
|
absolute name instead.)
|
|
|
|
@item
|
|
The function @code{file-newest-backup} returns the name of the most
|
|
recent backup file for @var{filename}, or @code{nil} that file has no
|
|
backup files.
|
|
|
|
@item
|
|
The list returned by @code{file-attributes} now has 12 elements. The
|
|
12th element is the file system number of the file system that the file
|
|
is in. This element together with the file's inode number, which is the
|
|
11th element, give enough information to distinguish any two files on
|
|
the system---no two files can have the same values for both of these
|
|
numbers.
|
|
|
|
@item
|
|
The new function @code{set-visited-file-modtime} updates the current
|
|
buffer's recorded modification time from the visited file's time.
|
|
|
|
This is useful if the buffer was not read from the file normally, or
|
|
if the file itself has been changed for some known benign reason.
|
|
|
|
If you give the function an argument, that argument specifies the new
|
|
value for the recorded modification time. The argument should be a list
|
|
of the form @code{(@var{high} . @var{low})} or @code{(@var{high}
|
|
@var{low})} containing two integers, each of which holds 16 bits of the
|
|
time. (This is the same format that @code[file-attributes} uses to
|
|
return time values.)
|
|
|
|
The new function @code{visited-file-modtime} returns the recorded last
|
|
modification time, in that same format.
|
|
|
|
@item
|
|
The function @code{directory-files} now takes an optional fourth
|
|
argument which, if non-@code{nil}, inhibits sorting the file names.
|
|
Use this if you want the utmost possible speed and don't care what order
|
|
the files are processed in.
|
|
|
|
If the order of processing is at all visible to the user, then the user
|
|
will probably be happier if you do sort the names.
|
|
|
|
@item
|
|
The variable @code{directory-abbrev-alist} contains an alist of
|
|
abbreviations to use for file directories. Each element has the form
|
|
@code{(@var{from} . @var{to})}, and says to replace @var{from} with
|
|
@var{to} when it appears in a directory name. This replacement is done
|
|
when setting up the default directory of a newly visited file. The
|
|
@var{from} string is actually a regular expression; it should always
|
|
start with @samp{^}.
|
|
|
|
You can set this variable in @file{site-init.el} to describe the
|
|
abbreviations appropriate for your site.
|
|
|
|
@item
|
|
The function @code{abbreviate-file-name} applies abbreviations from
|
|
@code{directory-abbrev-alist} to its argument, and substitutes @samp{~}
|
|
for the user's home directory.
|
|
|
|
Abbreviated directory names are useful for directories that are normally
|
|
accessed through symbolic links. If you think of the link's name as
|
|
``the name'' of the directory, you can define it as an abbreviation for
|
|
the directory's official name; then ordinarily Emacs will call that
|
|
directory by the link name you normally use.
|
|
|
|
@item
|
|
@code{write-region} can write a given string instead of text from the
|
|
buffer. Use the string as the first argument (in place of the
|
|
starting character position).
|
|
|
|
You can supply a second file name as the fifth argument (@var{visit}).
|
|
Use this to write the data to one file (the first argument,
|
|
@var{filename}) while nominally visiting a different file (the fifth
|
|
argument, @var{visit}). The argument @var{visit} is used in the echo
|
|
area message and also for file locking; @var{visit} is stored in
|
|
@code{buffer-file-name}.
|
|
|
|
@item
|
|
The value of @code{write-file-hooks} does not change when you switch to
|
|
a new major mode. The intention is that these hooks have to do with
|
|
where the file came from, and not with what it contains.
|
|
|
|
@item
|
|
There is a new hook variable for saving files:
|
|
@code{write-contents-hooks}. It works just like @code{write-file-hooks}
|
|
except that switching to a new major mode clears it back to @code{nil}.
|
|
Major modes should use this hook variable rather than
|
|
@code{write-file-hooks}.
|
|
|
|
@item
|
|
The hook @code{after-save-hook} runs just after a buffer has been saved
|
|
in its visited file.
|
|
|
|
@item
|
|
The new function @code{set-default-file-modes} sets the file protection
|
|
for new files created with Emacs. The argument must be an integer. (It
|
|
would be better to permit symbolic arguments like the @code{chmod}
|
|
program, but that would take more work than this function merits.)
|
|
|
|
Use the new function @code{default-file-modes} to read the current
|
|
default file mode.
|
|
|
|
@item
|
|
Call the new function @code{unix-sync} to force all pending disk output
|
|
to happen as soon as possible.
|
|
@end itemize
|
|
|
|
@section Making Certain File Names ``Magic''
|
|
|
|
You can implement special handling for a class of file names. You must
|
|
supply a regular expression to define the class of names (all those
|
|
which match the regular expression), plus a handler that implements all
|
|
the primitive Emacs file operations for file names that do match.
|
|
|
|
The value of @code{file-name-handler-alist} is a list of handlers,
|
|
together with regular expressions that decide when to apply each
|
|
handler. Each element has the form @code{(@var{regexp}
|
|
. @var{handler})}. If a file name matches @var{regexp}, then all work
|
|
on that file is done by calling @var{handler}.
|
|
|
|
All the Emacs primitives for file access and file name transformation
|
|
check the given file name against @code{file-name-handler-alist}, and
|
|
call @var{handler} to do the work if appropriate. The first argument
|
|
given to @var{handler} is the name of the primitive; the remaining
|
|
arguments are the arguments that were passed to that primitive. (The
|
|
first of these arguments is typically the file name itself.) For
|
|
example, if you do this:
|
|
|
|
@example
|
|
(file-exists-p @var{filename})
|
|
@end example
|
|
|
|
@noindent
|
|
and @var{filename} has handler @var{handler}, then @var{handler} is
|
|
called like this:
|
|
|
|
@example
|
|
(funcall @var{handler} 'file-exists-p @var{filename})
|
|
@end example
|
|
|
|
Here are the primitives that you can handle in this way:
|
|
|
|
@quotation
|
|
@code{add-name-to-file}, @code{copy-file}, @code{delete-directory},
|
|
@code{delete-file}, @code{directory-file-name}, @code{directory-files},
|
|
@code{dired-compress-file}, @code{dired-uncache},
|
|
@code{expand-file-name}, @code{file-accessible-directory-p},
|
|
@code{file-attributes}, @code{file-directory-p},
|
|
@code{file-executable-p}, @code{file-exists-p}, @code{file-local-copy},
|
|
@code{file-modes}, @code{file-name-all-completions},
|
|
@code{file-name-as-directory}, @code{file-name-completion},
|
|
@code{file-name-directory}, @code{file-name-nondirectory},
|
|
@code{file-name-sans-versions}, @code{file-newer-than-file-p},
|
|
@code{file-readable-p}, @code{file-symlink-p}, @code{file-writable-p},
|
|
@code{insert-directory}, @code{insert-file-contents},
|
|
@code{make-directory}, @code{make-symbolic-link}, @code{rename-file},
|
|
@code{set-file-modes}, @code{verify-visited-file-modtime},
|
|
@code{write-region}.
|
|
@end quotation
|
|
|
|
The handler function must handle all of the above operations, and
|
|
possibly others to be added in the future. Therefore, it should always
|
|
reinvoke the ordinary Lisp primitive when it receives an operation it
|
|
does not recognize. Here's one way to do this:
|
|
|
|
@smallexample
|
|
(defun my-file-handler (primitive &rest args)
|
|
;; @r{First check for the specific operations}
|
|
;; @r{that we have special handling for.}
|
|
(cond ((eq operation 'insert-file-contents) @dots{})
|
|
((eq operation 'write-region) @dots{})
|
|
@dots{}
|
|
;; @r{Handle any operation we don't know about.}
|
|
(t (let (file-name-handler-alist)
|
|
(apply operation args)))))
|
|
@end smallexample
|
|
|
|
The function @code{file-local-copy} copies file @var{filename} to the
|
|
local site, if it isn't there already. If @var{filename} specifies a
|
|
``magic'' file name which programs outside Emacs cannot directly read or
|
|
write, this copies the contents to an ordinary file and returns that
|
|
file's name.
|
|
|
|
If @var{filename} is an ordinary file name, not magic, then this function
|
|
does nothing and returns @code{nil}.
|
|
|
|
The function @code{unhandled-file-name-directory} is used to get a
|
|
non-magic directory name from an arbitrary file name. It uses the
|
|
directory part of the specified file name if that is not magic.
|
|
Otherwise, it asks the file name's handler what to do.
|
|
|
|
@section Frames
|
|
@cindex frame
|
|
|
|
Emacs now supports multiple X windows via a new data type known as a
|
|
@dfn{frame}.
|
|
|
|
A frame is a rectangle on the screen that contains one or more Emacs
|
|
windows. Subdividing a frame works just like subdividing the screen in
|
|
earlier versions of Emacs.
|
|
|
|
@cindex terminal frame
|
|
There are two kinds of frames: terminal frames and X window frames.
|
|
Emacs creates one terminal frame when it starts up with no X display; it
|
|
uses Termcap or Terminfo to display using characters. There is no way
|
|
to create another terminal frame after startup. If Emacs has an X
|
|
display, it does not make a terminal frame, and there is none.
|
|
|
|
@cindex X window frame
|
|
When you are using X windows, Emacs starts out with a single X window
|
|
frame. You can create any number of X window frames using
|
|
@code{make-frame}.
|
|
|
|
Use the predicate @code{framep} to determine whether a given Lisp object
|
|
is a frame.
|
|
|
|
The function @code{redraw-frame} redisplays the entire contents of a
|
|
given frame.
|
|
|
|
@subsection Creating and Deleting Frames
|
|
|
|
Use @code{make-frame} to create a new frame (supported under X Windows
|
|
only). This is the only primitive for creating frames.
|
|
|
|
@code{make-frame} takes just one argument, which is an alist
|
|
specifying frame parameters. Any parameters not mentioned in the
|
|
argument alist default based on the value of @code{default-frame-alist};
|
|
parameters not specified there default from the standard X defaults file
|
|
and X resources.
|
|
|
|
When you invoke Emacs, if you specify arguments for window appearance
|
|
and so forth, these go into @code{default-frame-alist} and that is how
|
|
they have their effect.
|
|
|
|
You can specify the parameters for the initial startup X window frame by
|
|
setting @code{initial-frame-alist} in your @file{.emacs} file. If these
|
|
parameters specify a separate minibuffer-only frame, and you have not
|
|
created one, Emacs creates one for you, using the parameter values
|
|
specified in @code{minibuffer-frame-alist}.
|
|
|
|
You can specify the size and position of a frame using the frame
|
|
parameters @code{left}, @code{top}, @code{height} and @code{width}. You
|
|
must specify either both size parameters or neither. You must specify
|
|
either both position parameters or neither. The geometry parameters
|
|
that you don't specify are chosen by the window manager in its usual
|
|
fashion.
|
|
|
|
The function @code{x-parse-geometry} converts a standard X windows
|
|
geometry string to an alist which you can use as part of the argument to
|
|
@code{make-frame}.
|
|
|
|
Use the function @code{delete-frame} to eliminate a frame. Frames are
|
|
like buffers where deletion is concerned; a frame actually continues to
|
|
exist as a Lisp object until it is deleted @emph{and} there are no
|
|
references to it, but once it is deleted, it has no further effect on
|
|
the screen.
|
|
|
|
The function @code{frame-live-p} returns non-@code{nil} if the argument
|
|
(a frame) has not been deleted.
|
|
|
|
@subsection Finding All Frames
|
|
|
|
The function @code{frame-list} returns a list of all the frames that have
|
|
not been deleted. It is analogous to @code{buffer-list}. The list that
|
|
you get is newly created, so modifying the list doesn't have any effect
|
|
on the internals of Emacs. The function @code{visible-frame-list} returns
|
|
the list of just the frames that are visible.
|
|
|
|
@code{next-frame} lets you cycle conveniently through all the frames from an
|
|
arbitrary starting point. Its first argument is a frame. Its second
|
|
argument @var{minibuf} says what to do about minibuffers:
|
|
|
|
@table @asis
|
|
@item @code{nil}
|
|
Exclude minibuffer-only frames.
|
|
@item a window
|
|
Consider only the frames using that particular window as their
|
|
minibuffer.
|
|
@item anything else
|
|
Consider all frames.
|
|
@end table
|
|
|
|
@subsection Frames and Windows
|
|
|
|
All the non-minibuffer windows in a frame are arranged in a tree of
|
|
subdivisions; the root of this tree is available via the function
|
|
@code{frame-root-window}. Each window is part of one and only one
|
|
frame; you can get the frame with @code{window-frame}.
|
|
|
|
At any time, exactly one window on any frame is @dfn{selected within the
|
|
frame}. You can get the frame's current selected window with
|
|
@code{frame-selected-window}. The significance of this designation is
|
|
that selecting the frame selects for Emacs as a whole the window
|
|
currently selected within that frame.
|
|
|
|
Conversely, selecting a window for Emacs with @code{select-window} also
|
|
makes that window selected within its frame.
|
|
|
|
@subsection Frame Visibility
|
|
|
|
A frame may be @dfn{visible}, @dfn{invisible}, or @dfn{iconified}. If
|
|
it is invisible, it doesn't show in the screen, not even as an icon.
|
|
You can set the visibility status of a frame with
|
|
@code{make-frame-visible}, @code{make-frame-invisible}, and
|
|
@code{iconify-frame}. You can examine the visibility status with
|
|
@code{frame-visible-p}---it returns @code{t} for a visible frame,
|
|
@code{nil} for an invisible frame, and @code{icon} for an iconified
|
|
frame.
|
|
|
|
@subsection Selected Frame
|
|
|
|
At any time, one frame in Emacs is the @dfn{selected frame}. The selected
|
|
window always resides on the selected frame.
|
|
|
|
@defun selected-frame
|
|
This function returns the selected frame.
|
|
@end defun
|
|
|
|
The X server normally directs keyboard input to the X window that the
|
|
mouse is in. Some window managers use mouse clicks or keyboard events
|
|
to @dfn{shift the focus} to various X windows, overriding the normal
|
|
behavior of the server.
|
|
|
|
Lisp programs can switch frames ``temporarily'' by calling the function
|
|
@code{select-frame}. This does not override the window manager; rather,
|
|
it escapes from the window manager's control until that control is
|
|
somehow reasserted. The function takes one argument, a frame, and
|
|
selects that frame. The selection lasts until the next time the user
|
|
does something to select a different frame, or until the next time this
|
|
function is called.
|
|
|
|
Emacs cooperates with the X server and the window managers by arranging
|
|
to select frames according to what the server and window manager ask
|
|
for. It does so by generating a special kind of input event, called a
|
|
@dfn{focus} event. The command loop handles a focus event by calling
|
|
@code{internal-select-frame}. @xref{Focus Events}.
|
|
|
|
@subsection Frame Size and Position
|
|
|
|
The new functions @code{frame-height} and @code{frame-width} return the
|
|
height and width of a specified frame (or of the selected frame),
|
|
measured in characters.
|
|
|
|
The new functions @code{frame-pixel-height} and @code{frame-pixel-width}
|
|
return the height and width of a specified frame (or of the selected
|
|
frame), measured in pixels.
|
|
|
|
The new functions @code{frame-char-height} and @code{frame-char-width}
|
|
return the height and width of a character in a specified frame (or in
|
|
the selected frame), measured in pixels.
|
|
|
|
@code{set-frame-size} sets the size of a frame, measured in characters;
|
|
its arguments are @var{frame}, @var{cols} and @var{rows}. To set the
|
|
size with values measured in pixels, you can use
|
|
@code{modify-frame-parameters}.
|
|
|
|
The function @code{set-frame-position} sets the position of the top left
|
|
corner of a frame. Its arguments are @var{frame}, @var{left} and
|
|
@var{top}.
|
|
|
|
@ignore
|
|
New functions @code{set-frame-height} and @code{set-frame-width} set the
|
|
size of a specified frame. The frame is the first argument; the size is
|
|
the second.
|
|
@end ignore
|
|
|
|
@subsection Frame Parameters
|
|
|
|
A frame has many parameters that affect how it displays. Use the
|
|
function @code{frame-parameters} to get an alist of all the parameters
|
|
of a given frame. To alter parameters, use
|
|
@code{modify-frame-parameters}, which takes two arguments: the frame to
|
|
modify, and an alist of parameters to change and their new values. Each
|
|
element of @var{alist} has the form @code{(@var{parm} . @var{value})},
|
|
where @var{parm} is a symbol. Parameters that aren't meaningful are
|
|
ignored. If you don't mention a parameter in @var{alist}, its value
|
|
doesn't change.
|
|
|
|
Just what parameters a frame has depends on what display mechanism it
|
|
uses. Here is a table of the parameters of an X
|
|
window frame:
|
|
|
|
@table @code
|
|
@item name
|
|
The name of the frame.
|
|
|
|
@item left
|
|
The screen position of the left edge.
|
|
|
|
@item top
|
|
The screen position of the top edge.
|
|
|
|
@item height
|
|
The height of the frame contents, in pixels.
|
|
|
|
@item width
|
|
The width of the frame contents, in pixels.
|
|
|
|
@item window-id
|
|
The number of the X window for the frame.
|
|
|
|
@item minibuffer
|
|
Whether this frame has its own minibuffer.
|
|
@code{t} means yes, @code{none} means no,
|
|
@code{only} means this frame is just a minibuffer,
|
|
a minibuffer window (in some other frame)
|
|
means the new frame uses that minibuffer.
|
|
|
|
@item font
|
|
The name of the font for the text.
|
|
|
|
@item foreground-color
|
|
The color to use for the inside of a character.
|
|
Use strings to designate colors;
|
|
X windows defines the meaningful color names.
|
|
|
|
@item background-color
|
|
The color to use for the background of text.
|
|
|
|
@item mouse-color
|
|
The color for the mouse cursor.
|
|
|
|
@item cursor-color
|
|
The color for the cursor that shows point.
|
|
|
|
@item border-color
|
|
The color for the border of the frame.
|
|
|
|
@item cursor-type
|
|
The way to display the cursor. There are two legitimate values:
|
|
@code{bar} and @code{box}. The value @code{bar} specifies a vertical
|
|
bar between characters as the cursor. The value @code{box} specifies an
|
|
ordinary black box overlaying the character after point; that is the
|
|
default.
|
|
|
|
@item icon-type
|
|
Non-@code{nil} for a bitmap icon, @code{nil} for a text icon.
|
|
|
|
@item border-width
|
|
The width in pixels of the window border.
|
|
|
|
@item internal-border-width
|
|
The distance in pixels between text and border.
|
|
|
|
@item auto-raise
|
|
Non-@code{nil} means selecting the frame raises it.
|
|
|
|
@item auto-lower
|
|
Non-@code{nil} means deselecting the frame lowers it.
|
|
|
|
@item vertical-scrollbar
|
|
Non-@code{nil} gives the frame a scroll bar
|
|
for vertical scrolling.
|
|
|
|
@item horizontal-scrollbar
|
|
Non-@code{nil} gives the frame a scroll bar
|
|
for horizontal scrolling.
|
|
@end table
|
|
|
|
@subsection Minibufferless Frames
|
|
|
|
Normally, each frame has its own minibuffer window at the bottom, which
|
|
is used whenever that frame is selected. However, you can also create
|
|
frames with no minibuffers. These frames must use the minibuffer window
|
|
of some other frame.
|
|
|
|
The variable @code{default-minibuffer-frame} specifies where to find a
|
|
minibuffer for frames created without minibuffers of their own. Its
|
|
value should be a frame which does have a minibuffer.
|
|
|
|
You can also specify a minibuffer window explicitly when you create a
|
|
frame; then @code{default-minibuffer-frame} is not used.
|
|
|
|
@section X Windows Features
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The new functions @code{mouse-position} and @code{set-mouse-position} give
|
|
access to the current position of the mouse.
|
|
|
|
@code{mouse-position} returns a description of the position of the mouse.
|
|
The value looks like @code{(@var{frame} @var{x} . @var{y})}, where @var{x}
|
|
and @var{y} are measured in pixels relative to the top left corner of
|
|
the inside of @var{frame}.
|
|
|
|
@code{set-mouse-position} takes three arguments, @var{frame}, @var{x}
|
|
and @var{y}, and warps the mouse cursor to that location on the screen.
|
|
|
|
@item
|
|
@code{track-mouse} is a new special form for tracking mouse motion.
|
|
Use it in definitions of mouse clicks that want pay to attention to
|
|
the motion of the mouse, not just where the buttons are pressed and
|
|
released. Here is how to use it:
|
|
|
|
@example
|
|
(track-mouse @var{body}@dots{})
|
|
@end example
|
|
|
|
While @var{body} executes, mouse motion generates input events just as mouse
|
|
clicks do. @var{body} can read them with @code{read-event} or
|
|
@code{read-key-sequence}.
|
|
|
|
@code{track-mouse} returns the value of the last form in @var{body}.
|
|
|
|
The format of these events is described under ``New features for key
|
|
bindings and input.''
|
|
@c ???
|
|
|
|
@item
|
|
@code{x-set-selection} sets a ``selection'' in the X Windows server.
|
|
It takes two arguments: a selection type @var{type}, and the value to
|
|
assign to it, @var{data}. If @var{data} is @code{nil}, it means to
|
|
clear out the selection. Otherwise, @var{data} may be a string, a
|
|
symbol, an integer (or a cons of two integers or list of two integers),
|
|
or a cons of two markers pointing to the same buffer. In the last case,
|
|
the selection is considered to be the text between the markers. The
|
|
data may also be a vector of valid non-vector selection values.
|
|
|
|
Each possible @var{type} has its own selection value, which changes
|
|
independently. The usual values of @var{type} are @code{PRIMARY} and
|
|
@code{SECONDARY}; these are symbols with upper-case names, in accord
|
|
with X Windows conventions. The default is @code{PRIMARY}.
|
|
|
|
To get the value of the selection, call @code{x-get-selection}. This
|
|
function accesses selections set up by Emacs and those set up by other X
|
|
clients. It takes two optional arguments, @var{type} and
|
|
@var{data-type}. The default for @var{type} is @code{PRIMARY}.
|
|
|
|
The @var{data-type} argument specifies the form of data conversion to
|
|
use; meaningful values include @code{TEXT}, @code{STRING},
|
|
@code{TARGETS}, @code{LENGTH}, @code{DELETE}, @code{FILE_NAME},
|
|
@code{CHARACTER_POSITION}, @code{LINE_NUMBER}, @code{COLUMN_NUMBER},
|
|
@code{OWNER_OS}, @code{HOST_NAME}, @code{USER}, @code{CLASS},
|
|
@code{NAME}, @code{ATOM}, and @code{INTEGER}. (These are symbols with
|
|
upper-case names in accord with X Windows conventions.)
|
|
The default for @var{data-type} is @code{STRING}.
|
|
|
|
@item
|
|
X Windows has a set of numbered @dfn{cut buffers} which can store text
|
|
or other data being moved between applications. Use
|
|
@code{x-get-cut-buffer} to get the contents of a cut buffer; specify the
|
|
cut buffer number as argument. Use @code{x-set-cut-buffer} with
|
|
argument @var{string} to store a new string into the first cut buffer
|
|
(moving the other values down through the series of cut buffers,
|
|
kill-ring-style).
|
|
|
|
Cut buffers are considered obsolete in X Windows, but Emacs supports
|
|
them for the sake of X clients that still use them.
|
|
|
|
@item
|
|
You can close the connection with the X Windows server with
|
|
the function @code{x-close-current-connection}. This takes no arguments.
|
|
|
|
Then you can connect to a different X Windows server with
|
|
@code{x-open-connection}. The first argument, @var{display}, is the
|
|
name of the display to connect to.
|
|
|
|
The optional second argument @var{xrm-string} is a string of resource
|
|
names and values, in the same format used in the @file{.Xresources}
|
|
file. The values you specify override the resource values recorded in
|
|
the X Windows server itself. Here's an example of what this string
|
|
might look like:
|
|
|
|
@example
|
|
"*BorderWidth: 3\n*InternalBorder: 2\n"
|
|
@end example
|
|
|
|
@item
|
|
A series of new functions give you information about the X server and
|
|
the screen you are using.
|
|
|
|
@table @code
|
|
@item x-display-screens
|
|
The number of screens associated with the current display.
|
|
|
|
@item x-server-version
|
|
The version numbers of the X server in use.
|
|
|
|
@item x-server-vendor
|
|
The vendor supporting the X server in use.
|
|
|
|
@item x-display-pixel-height
|
|
The height of this X screen in pixels.
|
|
|
|
@item x-display-mm-height
|
|
The height of this X screen in millimeters.
|
|
|
|
@item x-display-pixel-width
|
|
The width of this X screen in pixels.
|
|
|
|
@item x-display-mm-width
|
|
The width of this X screen in millimeters.
|
|
|
|
@item x-display-backing-store
|
|
The backing store capability of this screen. Values can be the symbols
|
|
@code{always}, @code{when-mapped}, or @code{not-useful}.
|
|
|
|
@item x-display-save-under
|
|
Non-@code{nil} if this X screen supports the SaveUnder feature.
|
|
|
|
@item x-display-planes
|
|
The number of planes this display supports.
|
|
|
|
@item x-display-visual-class
|
|
The visual class for this X screen. The value is one of the symbols
|
|
@code{static-gray}, @code{gray-scale}, @code{static-color},
|
|
@code{pseudo-color}, @code{true-color}, and @code{direct-color}.
|
|
|
|
@item x-display-color-p
|
|
@code{t} if the X screen in use is a color screen.
|
|
|
|
@item x-display-color-cells
|
|
The number of color cells this X screen supports.
|
|
@end table
|
|
|
|
There is also a variable @code{x-no-window-manager}, whose value is
|
|
@code{t} if no X window manager is in use.
|
|
|
|
@item
|
|
The function @code{x-synchronize} enables or disables an X Windows
|
|
debugging mode: synchronous communication. It takes one argument,
|
|
non-@code{nil} to enable the mode and @code{nil} to disable.
|
|
|
|
In synchronous mode, Emacs waits for a response to each X protocol
|
|
command before doing anything else. This means that errors are reported
|
|
right away, and you can directly find the erroneous command.
|
|
Synchronous mode is not the default because it is much slower.
|
|
|
|
@item
|
|
The function @code{x-get-resource} retrieves a resource value from the X
|
|
Windows defaults database. Its three arguments are @var{attribute},
|
|
@var{name} and @var{class}. It searches using a key of the form
|
|
@samp{@var{instance}.@var{attribute}}, with class @samp{Emacs}, where
|
|
@var{instance} is the name under which Emacs was invoked.
|
|
|
|
The optional arguments @var{component} and @var{subclass} add to the key
|
|
and the class, respectively. You must specify both of them or neither.
|
|
If you specify them, the key is
|
|
@samp{@var{instance}.@var{component}.@var{attribute}}, and the class is
|
|
@samp{Emacs.@var{subclass}}.
|
|
|
|
@item
|
|
@code{x-color-display-p} returns @code{t} if you are using an X Window
|
|
server with a color display, and @code{nil} otherwise.
|
|
|
|
@c ??? Name being changed from x-defined-color.
|
|
@code{x-color-defined-p} takes as argument a string describing a color; it
|
|
returns @code{t} if the display supports that color. (If the color is
|
|
@code{"black"} or @code{"white"} then even black-and-white displays
|
|
support it.)
|
|
|
|
@item
|
|
@code{x-popup-menu} has been generalized. It now accepts a keymap as
|
|
the @var{menu} argument. Then the menu items are the prompt strings of
|
|
individual key bindings, and the item values are the keys which have
|
|
those bindings.
|
|
|
|
You can also supply a list of keymaps as the first argument; then each
|
|
keymap makes one menu pane (but keymaps that don't provide any menu
|
|
items don't appear in the menu at all).
|
|
|
|
@code{x-popup-menu} also accepts a mouse button event as the
|
|
@var{position} argument. Then it displays the menu at the location at
|
|
which the event took place. This is convenient for mouse-invoked
|
|
commands that pop up menus.
|
|
|
|
@ignore
|
|
@item
|
|
x-pointer-shape, x-nontext-pointer-shape, x-mode-pointer-shape.
|
|
@end ignore
|
|
|
|
@item
|
|
You can use the function @code{x-rebind-key} to change the sequence
|
|
of characters generated by one of the keyboard keys. This works
|
|
only with X Windows.
|
|
|
|
The first two arguments, @var{keycode} and @var{shift-mask}, should be
|
|
numbers representing the keyboard code and shift mask respectively.
|
|
They specify what key to change.
|
|
|
|
The third argument, @var{newstring}, is the new definition of the key.
|
|
It is a sequence of characters that the key should produce as input.
|
|
|
|
The shift mask value is a combination of bits according to this table:
|
|
|
|
@table @asis
|
|
@item 8
|
|
Control
|
|
@item 4
|
|
Meta
|
|
@item 2
|
|
Shift
|
|
@item 1
|
|
Shift Lock
|
|
@end table
|
|
|
|
If you specify @code{nil} for @var{shift-mask}, then the key specified
|
|
by @var{keycode} is redefined for all possible shift combinations.
|
|
|
|
For the possible values of @var{keycode} and their meanings, see the
|
|
file @file{/usr/lib/Xkeymap.txt}. Keep in mind that the codes in that
|
|
file are in octal!
|
|
|
|
@ignore @c Presumably this is already fixed
|
|
NOTE: due to an X bug, this function will not take effect unless the
|
|
user has a @file{~/.Xkeymap} file. (See the documentation for the
|
|
@code{keycomp} program.) This problem will be fixed in X version 11.
|
|
@end ignore
|
|
|
|
The related function @code{x-rebind-keys} redefines a single keyboard
|
|
key, specifying the behavior for each of the 16 shift masks
|
|
independently. The first argument is @var{keycode}, as in
|
|
@code{x-rebind-key}. The second argument @var{strings} is a list of 16
|
|
elements, one for each possible shift mask value; each element says how
|
|
to redefine the key @var{keycode} with the corresponding shift mask
|
|
value. If an element is a string, it is the new definition. If an
|
|
element is @code{nil}, the definition does not change for that shift
|
|
mask.
|
|
|
|
@item
|
|
The function @code{x-geometry} parses a string specifying window size
|
|
and position in the usual fashion for X windows. It returns an alist
|
|
describing which parameters were specified, and the values that were
|
|
given for them.
|
|
|
|
The elements of the alist look like @code{(@var{parameter} .
|
|
@var{value})}. The possible @var{parameter} values are @code{left},
|
|
@code{top}, @code{width}, and @code{height}.
|
|
@end itemize
|
|
|
|
@section New Window Features
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The new function @code{window-at} tells you which window contains a
|
|
given horizontal and vertical position on a specified frame. Call it
|
|
with three arguments, like this:
|
|
|
|
@example
|
|
(window-at @var{x} @var{column} @var{frame})
|
|
@end example
|
|
|
|
The function returns the window which contains that cursor position in
|
|
the frame @var{frame}. If you omit @var{frame}, the selected frame is
|
|
used.
|
|
|
|
@item
|
|
The function @code{coordinates-in-window-p} takes two arguments and
|
|
checks whether a particular frame position falls within a particular
|
|
window.
|
|
|
|
@example
|
|
(coordinates-in-window-p @var{coordinates} @var{window})
|
|
@end example
|
|
|
|
The argument @var{coordinates} is a cons cell of this form:
|
|
|
|
@example
|
|
(@var{x} . @var{y})
|
|
@end example
|
|
|
|
@noindent
|
|
The two coordinates are measured in characters, and count from the top
|
|
left corner of the screen or frame.
|
|
|
|
The value of the function tells you what part of the window the position
|
|
is in. The possible values are:
|
|
|
|
@table @code
|
|
@item (@var{relx} . @var{rely})
|
|
The coordinates are inside @var{window}. The numbers @var{relx} and
|
|
@var{rely} are equivalent window-relative coordinates, counting from 0
|
|
at the top left corner of the window.
|
|
|
|
@item mode-line
|
|
The coordinates are in the mode line of @var{window}.
|
|
|
|
@item vertical-split
|
|
The coordinates are in the vertical line between @var{window} and its
|
|
neighbor to the right.
|
|
|
|
@item nil
|
|
The coordinates are not in any sense within @var{window}.
|
|
@end table
|
|
|
|
You need not specify a frame when you call
|
|
@code{coordinates-in-window-p}, because it assumes you mean the frame
|
|
which window @var{window} is on.
|
|
|
|
@item
|
|
The function @code{minibuffer-window} now accepts a frame as argument
|
|
and returns the minibuffer window used for that frame. If you don't
|
|
specify a frame, the currently selected frame is used. The minibuffer
|
|
window may be on the frame in question, but if that frame has no
|
|
minibuffer of its own, it uses the minibuffer window of some other
|
|
frame, and @code{minibuffer-window} returns that window.
|
|
|
|
@item
|
|
Use @code{window-live-p} to test whether a window is still alive (that
|
|
is, not deleted).
|
|
|
|
@item
|
|
Use @code{window-minibuffer-p} to determine whether a given window is a
|
|
minibuffer or not. It no longer works to do this by comparing the
|
|
window with the result of @code{(minibuffer-window)}, because there can
|
|
be more than one minibuffer window at a time (if you have multiple
|
|
frames).
|
|
|
|
@item
|
|
If you set the variable @code{pop-up-frames} non-@code{nil}, then the
|
|
functions to show something ``in another window'' actually create a new
|
|
frame for the new window. Thus, you will tend to have a frame for each
|
|
window, and you can easily have a frame for each buffer.
|
|
|
|
The value of the variable @code{pop-up-frame-function} controls how new
|
|
frames are made. The value should be a function which takes no
|
|
arguments and returns a frame. The default value is a function which
|
|
creates a frame using parameters from @code{pop-up-frame-alist}.
|
|
|
|
@item
|
|
@code{display-buffer} is the basic primitive for finding a way to show a
|
|
buffer on the screen. You can customize its behavior by storing a
|
|
function in the variable @code{display-buffer-function}. If this
|
|
variable is non-@code{nil}, then @code{display-buffer} calls it to do
|
|
the work. Your function should accept two arguments, as follows:
|
|
|
|
@table @var
|
|
@item buffer
|
|
The buffer to be displayed.
|
|
|
|
@item flag
|
|
A flag which, if non-@code{nil}, means you should find another window to
|
|
display @var{buffer} in, even if it is already visible in the selected
|
|
window.
|
|
@end table
|
|
|
|
The function you supply will be used by commands such as
|
|
@code{switch-to-buffer-other-window} and @code{find-file-other-window}
|
|
as well as for your own calls to @code{display-buffer}.
|
|
|
|
@item
|
|
@code{delete-window} now gives all of the deleted window's screen space
|
|
to a single neighboring window. Likewise, @code{enlarge-window} takes
|
|
space from only one neighboring window until that window disappears;
|
|
only then does it take from another window.
|
|
|
|
@item
|
|
@code{next-window} and @code{previous-window} accept another argument,
|
|
@var{all-frames}.
|
|
|
|
These functions now take three optional arguments: @var{window},
|
|
@var{minibuf} and @var{all-frames}. @var{window} is the window to start
|
|
from (@code{nil} means use the selected window). @var{minibuf} says
|
|
whether to include the minibuffer in the windows to cycle through:
|
|
@code{t} means yes, @code{nil} means yes if it is active, and anything
|
|
else means no.
|
|
|
|
Normally, these functions cycle through all the windows in the
|
|
selected frame, plus the minibuffer used by the selected frame even if
|
|
it lies in some other frame.
|
|
|
|
If @var{all-frames} is @code{t}, then these functions cycle through
|
|
all the windows in all the frames that currently exist. If
|
|
@var{all-frames} is neither @code{t} nor @code{nil}, then they limit
|
|
themselves strictly to the windows in the selected frame, excluding the
|
|
minibuffer in use if it lies in some other frame.
|
|
|
|
@item
|
|
The functions @code{get-lru-window} and @code{get-largest-window} now
|
|
take an optional argument @var{all-frames}. If it is non-@code{nil},
|
|
the functions consider all windows on all frames. Otherwise, they
|
|
consider just the windows on the selected frame.
|
|
|
|
Likewise, @code{get-buffer-window} takes an optional second argument
|
|
@var{all-frames}.
|
|
|
|
@item
|
|
The variable @code{other-window-scroll-buffer} specifies which buffer
|
|
@code{scroll-other-window} should scroll.
|
|
|
|
@item
|
|
You can now mark a window as ``dedicated'' to its buffer.
|
|
Then Emacs will not try to use that window for any other buffer
|
|
unless you explicitly request it.
|
|
|
|
Use the new function @code{set-window-dedicated-p} to set the dedication
|
|
flag of a window @var{window} to the value @var{flag}. If @var{flag} is
|
|
@code{t}, this makes the window dedicated. If @var{flag} is
|
|
@code{nil}, this makes the window non-dedicated.
|
|
|
|
Use @code{window-dedicated-p} to examine the dedication flag of a
|
|
specified window.
|
|
|
|
@item
|
|
The new function @code{walk-windows} cycles through all visible
|
|
windows, calling @code{proc} once for each window with the window as
|
|
its sole argument.
|
|
|
|
The optional second argument @var{minibuf} says whether to include minibuffer
|
|
windows. A value of @code{t} means count the minibuffer window even if
|
|
not active. A value of @code{nil} means count it only if active. Any
|
|
other value means not to count the minibuffer even if it is active.
|
|
|
|
If the optional third argument @var{all-frames} is @code{t}, that means
|
|
include all windows in all frames. If @var{all-frames} is @code{nil},
|
|
it means to cycle within the selected frame, but include the minibuffer
|
|
window (if @var{minibuf} says so) that that frame uses, even if it is on
|
|
another frame. If @var{all-frames} is neither @code{nil} nor @code{t},
|
|
@code{walk-windows} sticks strictly to the selected frame.
|
|
|
|
@item
|
|
The function @code{window-end} is a counterpart to @code{window-start}:
|
|
it returns the buffer position of the end of the display in a given
|
|
window (or the selected window).
|
|
|
|
@item
|
|
The function @code{window-configuration-p} returns non-@code{nil} when
|
|
given an object that is a window configuration (such as is returned by
|
|
@code{current-window-configuration}).
|
|
@end itemize
|
|
|
|
@section Display Features
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@samp{%l} as a mode line item displays the current line number.
|
|
|
|
If the buffer is longer than @code{line-number-display-limit}
|
|
characters, or if lines are too long in the viscinity of the current
|
|
displayed text, then line number display is inhibited to save time.
|
|
|
|
The default contents of the mode line include the line number if
|
|
@code{line-number-mode} is non-@code{nil}.
|
|
|
|
@item
|
|
@code{baud-rate} is now a variable rather than a function. This is so
|
|
you can set it to reflect the effective speed of your terminal, when the
|
|
system doesn't accurately know the speed.
|
|
|
|
@item
|
|
You can now remove any echo area message and make the minibuffer
|
|
visible. To do this, call @code{message} with @code{nil} as the only
|
|
argument. This clears any existing message, and lets the current
|
|
minibuffer contents show through. Previously, there was no reliable way
|
|
to make sure that the minibuffer contents were visible.
|
|
|
|
@item
|
|
The variable @code{temp-buffer-show-hook} has been renamed
|
|
@code{temp-buffer-show-function}, because its value is a single function
|
|
(of one argument), not a normal hook.
|
|
|
|
@item
|
|
The new function @code{force-mode-line-update} causes redisplay
|
|
of the current buffer's mode line.
|
|
@end itemize
|
|
|
|
@section Display Tables
|
|
|
|
@cindex display table
|
|
You can use the @dfn{display table} feature to control how all 256
|
|
possible character codes display on the screen. This is useful for
|
|
displaying European languages that have letters not in the ASCII
|
|
character set.
|
|
|
|
The display table maps each character code into a sequence of
|
|
@dfn{glyphs}, each glyph being an image that takes up one character
|
|
position on the screen. You can also define how to display each glyph
|
|
on your terminal, using the @dfn{glyph table}.
|
|
|
|
@subsection Display Tables
|
|
|
|
Use @code{make-display-table} to create a display table. The table
|
|
initially has @code{nil} in all elements.
|
|
|
|
A display table is actually an array of 261 elements. The first 256
|
|
elements of a display table control how to display each possible text
|
|
character. The value should be @code{nil} or a vector (which is a
|
|
sequence of glyphs; see below). @code{nil} as an element means to
|
|
display that character following the usual display conventions.
|
|
|
|
The remaining five elements of a display table serve special purposes
|
|
(@code{nil} means use the default stated below):
|
|
|
|
@table @asis
|
|
@item 256
|
|
The glyph for the end of a truncated screen line (the default for this
|
|
is @samp{\}).
|
|
@item 257
|
|
The glyph for the end of a continued line (the default is @samp{$}).
|
|
@item 258
|
|
The glyph for the indicating an octal character code (the default is
|
|
@samp{\}).
|
|
@item 259
|
|
The glyph for indicating a control characters (the default is @samp{^}).
|
|
@item 260
|
|
The vector of glyphs for indicating the presence of invisible lines (the
|
|
default is @samp{...}).
|
|
@end table
|
|
|
|
Each buffer typically has its own display table. The display table for
|
|
the current buffer is stored in @code{buffer-display-table}. (This
|
|
variable automatically becomes local if you set it.) If this variable
|
|
is @code{nil}, the value of @code{standard-display-table} is used in
|
|
that buffer.
|
|
|
|
Each window can have its own display table, which overrides the display
|
|
table of the buffer it is showing.
|
|
|
|
If neither the selected window nor the current buffer has a display
|
|
table, and if @code{standard-display-table} is @code{nil}, then Emacs
|
|
uses the usual display conventions:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Character codes 32 through 127 map to glyph codes 32 through 127.
|
|
@item
|
|
Codes 0 through 31 map to sequences of two glyphs, where the first glyph
|
|
is the ASCII code for @samp{^}.
|
|
@item
|
|
Character codes 128 through 255 map to sequences of four glyphs, where
|
|
the first glyph is the ASCII code for @samp{\}, and the others represent
|
|
digits.
|
|
@end itemize
|
|
|
|
The usual display conventions are also used for any character whose
|
|
entry in the active display table is @code{nil}. This means that when
|
|
you set up a display table, you need not specify explicitly what to do
|
|
with each character, only the characters for which you want unusual
|
|
behavior.
|
|
|
|
@subsection Glyphs
|
|
|
|
@cindex glyph
|
|
A glyph stands for an image that takes up a single character position on
|
|
the screen. A glyph is represented in Lisp as an integer.
|
|
|
|
@cindex glyph table
|
|
The meaning of each integer, as a glyph, is defined by the glyph table,
|
|
which is the value of the variable @code{glyph-table}. It should be a
|
|
vector; the @var{g}th element defines glyph code @var{g}. The possible
|
|
definitions of a glyph code are:
|
|
|
|
@table @var
|
|
@item integer
|
|
Define this glyph code as an alias for code @var{integer}.
|
|
This is used with X windows to specify a face code.
|
|
|
|
@item string
|
|
Send the characters in @var{string} to the terminal to output
|
|
this glyph. This alternative is not available with X Windows.
|
|
|
|
@item @code{nil}
|
|
This glyph is simple. On an ordinary terminal, the glyph code mod 256
|
|
is the character to output. With X, the glyph code mod 256 is character
|
|
to output, and the glyph code divided by 256 specifies the @dfn{face
|
|
code} to use while outputting it.
|
|
@end table
|
|
|
|
Any glyph code beyond the length of the glyph table is automatically simple.
|
|
|
|
A face code for X windows is the combination of a font and a color.
|
|
Emacs uses integers to identify face codes. You can define a new face
|
|
code with @code{(x-set-face @var{face-code} @var{font} @var{foreground}
|
|
@var{background})}. @var{face-code} is an integer from 0 to 255; it
|
|
specifies which face to define. The other three arguments are strings:
|
|
@var{font} is the name of the font to use, and @var{foreground} and
|
|
@var{background} specify the colors to use.
|
|
|
|
If @code{glyph-table} is @code{nil}, then all possible glyph codes are
|
|
simple.
|
|
|
|
@subsection ISO Latin 1
|
|
|
|
If you have a terminal that can handle the entire ISO Latin 1 character
|
|
set, you can arrange to use that character set as follows:
|
|
|
|
@example
|
|
(require 'disp-table)
|
|
(standard-display-8bit 0 255)
|
|
@end example
|
|
|
|
If you are editing buffers written in the ISO Latin 1 character set and
|
|
your terminal doesn't handle anything but ASCII, you can load the file
|
|
@code{iso-ascii} to set up a display table which makes the other ISO
|
|
characters display as sequences of ASCII characters. For example, the
|
|
character ``o with umlaut'' displays as @samp{@{"o@}}.
|
|
|
|
Some European countries have terminals that don't support ISO Latin 1
|
|
but do support the special characters for that country's language. You
|
|
can define a display table to work one language using such terminals.
|
|
For an example, see @file{lisp/iso-swed.el}, which handles certain
|
|
Swedish terminals.
|
|
|
|
You can load the appropriate display table for your terminal
|
|
automatically by writing a terminal-specific Lisp file for the terminal
|
|
type.
|
|
|
|
@section New Input Event Formats
|
|
|
|
Mouse clicks, mouse movements and function keys no longer appear in the
|
|
input stream as characters; instead, other kinds of Lisp objects
|
|
represent them as input.
|
|
|
|
@itemize @bullet
|
|
@item
|
|
An ordinary input character event consists of a @dfn{basic code} between
|
|
0 and 255, plus any or all of these @dfn{modifier bits}:
|
|
|
|
@table @asis
|
|
@item meta
|
|
The 2**23 bit in the character code indicates a character
|
|
typed with the meta key held down.
|
|
|
|
@item control
|
|
The 2**22 bit in the character code indicates a non-@sc{ASCII}
|
|
control character.
|
|
|
|
@sc{ASCII} control characters such as @kbd{C-a} have special basic
|
|
codes of their own, so Emacs needs no special bit to indicate them.
|
|
Thus, the code for @kbd{C-a} is just 1.
|
|
|
|
But if you type a control combination not in @sc{ASCII}, such as
|
|
@kbd{%} with the control key, the numeric value you get is the code
|
|
for @kbd{%} plus 2**22 (assuming the terminal supports non-@sc{ASCII}
|
|
control characters).
|
|
|
|
@item shift
|
|
The 2**21 bit in the character code indicates an @sc{ASCII} control
|
|
character typed with the shift key held down.
|
|
|
|
For letters, the basic code indicates upper versus lower case; for
|
|
digits and punctuation, the shift key selects an entirely different
|
|
character with a different basic code. In order to keep within
|
|
the @sc{ASCII} character set whenever possible, Emacs avoids using
|
|
the 2**21 bit for those characters.
|
|
|
|
However, @sc{ASCII} provides no way to distinguish @kbd{C-A} from
|
|
@kbd{C-A}, so Emacs uses the 2**21 bit in @kbd{C-A} and not in
|
|
@kbd{C-a}.
|
|
|
|
@item hyper
|
|
The 2**20 bit in the character code indicates a character
|
|
typed with the hyper key held down.
|
|
|
|
@item super
|
|
The 2**19 bit in the character code indicates a character
|
|
typed with the super key held down.
|
|
|
|
@item alt
|
|
The 2**18 bit in the character code indicates a character typed with
|
|
the alt key held down. (On some terminals, the key labeled @key{ALT}
|
|
is actually the meta key.)
|
|
@end table
|
|
|
|
In the future, Emacs may support a larger range of basic codes. We may
|
|
also move the modifier bits to larger bit numbers. Therefore, you
|
|
should avoid mentioning specific bit numbers in your program. Instead,
|
|
the way to test the modifier bits of a character is with the function
|
|
@code{event-modifiers} (see below).
|
|
|
|
@item
|
|
Function keys are represented as symbols. The symbol's name is
|
|
the function key's label. For example, pressing a key labeled @key{F1}
|
|
places the symbol @code{f1} in the input stream.
|
|
|
|
There are a few exceptions to the symbol naming convention:
|
|
|
|
@table @asis
|
|
@item @code{kp-add}, @code{kp-decimal}, @code{kp-divide}, @dots{}
|
|
Keypad keys (to the right of the regular keyboard).
|
|
@item @code{kp-0}, @code{kp-1}, @dots{}
|
|
Keypad keys with digits.
|
|
@item @code{kp-f1}, @code{kp-f2}, @code{kp-f3}, @code{kp-f4}
|
|
Keypad PF keys.
|
|
@item @code{left}, @code{up}, @code{right}, @code{down}
|
|
Cursor arrow keys
|
|
@end table
|
|
|
|
You can use the modifier keys @key{CTRL}, @key{META}, @key{HYPER},
|
|
@key{SUPER}, @key{ALT} and @key{SHIFT} with function keys. The way
|
|
to represent them is with prefixes in the symbol name:
|
|
|
|
@table @samp
|
|
@item A-
|
|
The alt modifier.
|
|
@item C-
|
|
The control modifier.
|
|
@item H-
|
|
The hyper modifier.
|
|
@item M-
|
|
The meta modifier.
|
|
@item s-
|
|
The super modifier.
|
|
@item S-
|
|
The shift modifier.
|
|
@end table
|
|
|
|
Thus, the symbol for the key @key{F3} with @key{META} held down is
|
|
kbd{M-@key{F3}}. When you use more than one prefix, we recommend you
|
|
write them in alphabetical order (though the order does not matter in
|
|
arguments to the key-binding lookup and modification functions).
|
|
|
|
@item
|
|
Mouse events are represented as lists.
|
|
|
|
If you press a mouse button and release it at the same location, this
|
|
generates a ``click'' event. Mouse click events have this form:
|
|
|
|
@example
|
|
(@var{button-symbol}
|
|
(@var{window} (@var{column} . @var{row})
|
|
@var{buffer-pos} @var{timestamp}))
|
|
@end example
|
|
|
|
Here is what the elements normally mean:
|
|
|
|
@table @var
|
|
@item button-symbol
|
|
indicates which mouse button was used. It is one of the symbols
|
|
@code{mouse-1}, @code{mouse-2}, @dots{}, where the buttons are numbered
|
|
numbered left to right.
|
|
|
|
You can also use prefixes @samp{A-}, @samp{C-}, @samp{H-}, @samp{M-},
|
|
@samp{S-} and @samp{s-} for modifiers alt, control, hyper, meta, shift
|
|
and super, just as you would with function keys.
|
|
|
|
@item window
|
|
is the window in which the click occurred.
|
|
|
|
@item column
|
|
@itemx row
|
|
are the column and row of the click, relative to the top left corner of
|
|
@var{window}, which is @code{(0 . 0)}.
|
|
|
|
@item buffer-pos
|
|
is the buffer position of the character clicked on.
|
|
|
|
@item timestamp
|
|
is the time at which the event occurred, in milliseconds. (Since this
|
|
value wraps around the entire range of Emacs Lisp integers in about five
|
|
hours, it is useful only for relating the times of nearby events.)
|
|
@end table
|
|
|
|
The meanings of @var{buffer-pos}, @var{row} and @var{column} are
|
|
somewhat different when the event location is in a special part of the
|
|
screen, such as the mode line or a scroll bar.
|
|
|
|
If the position is in the window's scroll bar, then @var{buffer-pos} is
|
|
the symbol @code{vertical-scrollbar} or @code{horizontal-scrollbar}, and
|
|
the pair @code{(@var{column} . @var{row})} is instead a pair
|
|
@code{(@var{portion} . @var{whole})}, where @var{portion} is the
|
|
distance of the click from the top or left end of the scroll bar, and
|
|
@var{whole} is the length of the entire scroll bar.
|
|
|
|
If the position is on a mode line or the vertical line separating
|
|
@var{window} from its neighbor to the right, then @var{buffer-pos} is
|
|
the symbol @code{mode-line} or @code{vertical-line}. In this case
|
|
@var{row} and @var{column} do not have meaningful data.
|
|
|
|
@item
|
|
Releasing a mouse button above a different character position
|
|
generates a ``drag'' event, which looks like this:
|
|
|
|
@example
|
|
(@var{button-symbol}
|
|
(@var{window1} (@var{column1} . @var{row1})
|
|
@var{buffer-pos1} @var{timestamp1})
|
|
(@var{window2} (@var{column2} . @var{row2})
|
|
@var{buffer-pos2} @var{timestamp2}))
|
|
@end example
|
|
|
|
The name of @var{button-symbol} contains the prefix @samp{drag-}. The
|
|
second and third elements of the event give the starting and ending
|
|
position of the drag.
|
|
|
|
The @samp{drag-} prefix follows the modifier key prefixes such as
|
|
@samp{C-} and @samp{M-}.
|
|
|
|
If @code{read-key-sequence} receives a drag event which has no key
|
|
binding, and the corresponding click event does have a binding, it
|
|
changes the drag event into a click event at the drag's starting
|
|
position. This means that you don't have to distinguish between click
|
|
and drag events unless you want to.
|
|
|
|
@item
|
|
Click and drag events happen when you release a mouse button. Another
|
|
kind of event happens when you press a button. It looks just like a
|
|
click event, except that the name of @var{button-symbol} contains the
|
|
prefix @samp{down-}. The @samp{down-} prefix follows the modifier key
|
|
prefixes such as @samp{C-} and @samp{M-}.
|
|
|
|
The function @code{read-key-sequence}, and the Emacs command loop,
|
|
ignore any down events that don't have command bindings. This means
|
|
that you need not worry about defining down events unless you want them
|
|
to do something. The usual reason to define a down event is so that you
|
|
can track mouse motion until the button is released.
|
|
|
|
@item
|
|
For example, if the user presses and releases the left mouse button over
|
|
the same location, Emacs generates a sequence of events like this:
|
|
|
|
@smallexample
|
|
(down-mouse-1 (#<window 18 on NEWS> 2613 (0 . 38) -864320))
|
|
(mouse-1 (#<window 18 on NEWS> 2613 (0 . 38) -864180))
|
|
@end smallexample
|
|
|
|
Or, while holding the control key down, the user might hold down the
|
|
second mouse button, and drag the mouse from one line to the next.
|
|
That produces two events, as shown here:
|
|
|
|
@smallexample
|
|
(C-down-mouse-2 (#<window 18 on NEWS> 3440 (0 . 27) -731219))
|
|
(C-drag-mouse-2 (#<window 18 on NEWS> 3440 (0 . 27) -731219)
|
|
(#<window 18 on NEWS> 3510 (0 . 28) -729648))
|
|
@end smallexample
|
|
|
|
Or, while holding down the meta and shift keys, the user might press
|
|
the second mouse button on the window's mode line, and then drag the
|
|
mouse into another window. That produces an event like this:
|
|
|
|
@smallexample
|
|
(M-S-down-mouse-2 (#<window 18 on NEWS> mode-line (33 . 31) -457844))
|
|
(M-S-drag-mouse-2 (#<window 18 on NEWS> mode-line (33 . 31) -457844)
|
|
(#<window 20 on carlton-sanskrit.tex> 161 (33 . 3)
|
|
-453816))
|
|
@end smallexample
|
|
|
|
@item
|
|
A key sequence that starts with a mouse click is read using the keymaps
|
|
of the buffer in the window clicked on, not the current buffer.
|
|
|
|
This does not imply that clicking in a window selects that window or its
|
|
buffer. The execution of the command begins with no change in the
|
|
selected window or current buffer. However, the command can switch
|
|
windows or buffers if programmed to do so.
|
|
|
|
@item
|
|
Mouse motion events are represented by lists. During the execution of
|
|
the body of a @code{track-mouse} form, moving the mouse generates events
|
|
that look like this:
|
|
|
|
@example
|
|
(mouse-movement (@var{window} (@var{column} . @var{row})
|
|
@var{buffer-pos} @var{timestamp}))
|
|
@end example
|
|
|
|
The second element of the list describes the current position of the
|
|
mouse, just as in a mouse click event.
|
|
|
|
Outside of @code{track-mouse} forms, Emacs does not generate events for
|
|
mere motion of the mouse, and these events do not appear.
|
|
|
|
@item
|
|
Focus shifts between frames are represented by lists.
|
|
|
|
When the mouse shifts temporary input focus from one frame to another,
|
|
Emacs generates an event like this:
|
|
|
|
@example
|
|
(switch-frame @var{new-frame})
|
|
@end example
|
|
|
|
@noindent
|
|
where @var{new-frame} is the frame switched to.
|
|
|
|
In X windows, most window managers are set up so that just moving the
|
|
mouse into a window is enough to set the focus there. As far as the
|
|
user concern, Emacs behaves consistently with this. However, there is
|
|
no need for the Lisp program to know about the focus change until some
|
|
other kind of input arrives. So Emacs generates the focus event only
|
|
when the user actually types a keyboard key or presses a mouse button in
|
|
the new frame; just moving the mouse between frames does not generate a
|
|
focus event.
|
|
|
|
The global key map usually binds this event to the
|
|
@code{internal-select-frame} function, so that characters typed at a
|
|
frame apply to that frame's selected window.
|
|
|
|
If the user switches frames in the middle of a key sequence, then Emacs
|
|
delays the @code{switch-frame} event until the key sequence is over.
|
|
For example, suppose @kbd{C-c C-a} is a key sequence in the current
|
|
buffer's keymaps. If the user types @kbd{C-c}, moves the mouse to
|
|
another frame, and then types @kbd{C-a}, @code{read-key-sequence}
|
|
returns the sequence @code{"\C-c\C-a"}, and the next call to
|
|
@code{read-event} or @code{read-key-sequence} will return the
|
|
@code{switch-frame} event.
|
|
@end itemize
|
|
|
|
@section Working with Input Events
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Functions which work with key sequences now handle non-character
|
|
events. Functions like @code{define-key}, @code{global-set-key}, and
|
|
@code{local-set-key} used to accept strings representing key sequences;
|
|
now, since events may be arbitrary lisp objects, they also accept
|
|
vectors. The function @code{read-key-sequence} may return a string or a
|
|
vector, depending on whether or not the sequence read contains only
|
|
characters.
|
|
|
|
List events may be represented by the symbols at their head; to bind
|
|
clicks of the left mouse button, you need only present the symbol
|
|
@code{mouse-1}, not an entire mouse click event. If you do put an event
|
|
which is a list in a key sequence, only the event's head symbol is used
|
|
in key lookups.
|
|
|
|
For example, to globally bind the left mouse button to the function
|
|
@code{mouse-set-point}, you could evaluate this:
|
|
|
|
@example
|
|
(global-set-key [mouse-1] 'mouse-set-point)
|
|
@end example
|
|
|
|
To bind the sequence @kbd{C-c @key{F1}} to the command @code{tex-view}
|
|
in @code{tex-mode-map}, you could evaluate this:
|
|
|
|
@example
|
|
(define-key tex-mode-map [?\C-c f1] 'tex-view)
|
|
@end example
|
|
|
|
To find the binding for the function key labeled @key{NEXT} in
|
|
@code{minibuffer-local-map}, you could evaluate this:
|
|
|
|
@example
|
|
(lookup-key minibuffer-local-map [next])
|
|
@result{} next-history-element
|
|
@end example
|
|
|
|
If you call the function @code{read-key-sequence} and then press
|
|
@kbd{C-x C-@key{F5}}, here is how it behaves:
|
|
|
|
@example
|
|
(read-key-sequence "Press `C-x C-F5': ")
|
|
@result{} [24 C-f5]
|
|
@end example
|
|
|
|
Note that @samp{24} is the character @kbd{C-x}.
|
|
|
|
@item
|
|
The documentation functions (@code{single-key-description},
|
|
@code{key-description}, etc.) now handle the new event types. Wherever
|
|
a string of keyboard input characters was acceptable in previous
|
|
versions of Emacs, a vector of events should now work.
|
|
|
|
@item
|
|
Special parts of a window can have their own bindings for mouse events.
|
|
|
|
When mouse events occur in special parts of a window, such as a mode
|
|
line or a scroll bar, the event itself shows nothing special---only the
|
|
symbol that would normally represent that mouse button and modifier
|
|
keys. The information about the screen region is kept in other parts
|
|
of the event list. But @code{read-key-sequence} translates this
|
|
information into imaginary prefix keys, all of which are symbols:
|
|
@code{mode-line}, @code{vertical-line}, @code{horizontal-scrollbar} and
|
|
@code{vertical-scrollbar}.
|
|
|
|
For example, if you call @code{read-key-sequence} and then click the
|
|
mouse on the window's mode line, this is what happens:
|
|
|
|
@smallexample
|
|
(read-key-sequence "Click on the mode line: ")
|
|
@result{} [mode-line (mouse-1 (#<window 6 on NEWS> mode-line
|
|
(40 . 63) 5959987))]
|
|
@end smallexample
|
|
|
|
You can define meanings for mouse clicks in special window regions by
|
|
defining key sequences using these imaginary prefix keys. For example,
|
|
here is how to bind the third mouse button on a window's mode line
|
|
delete the window:
|
|
|
|
@example
|
|
(global-set-key [mode-line mouse-3] 'mouse-delete-window)
|
|
@end example
|
|
|
|
Here's how to bind the middle button (modified by @key{META}) on the
|
|
vertical line at the right of a window to scroll the window to the
|
|
left.
|
|
|
|
@example
|
|
(global-set-key [vertical-line M-mouse-2] 'scroll-left)
|
|
@end example
|
|
|
|
@item
|
|
Decomposing an event symbol.
|
|
|
|
Each symbol used to identify a function key or mouse button has a
|
|
property named @code{event-symbol-elements}, which is a list containing
|
|
an unmodified version of the symbol, followed by modifiers the symbol
|
|
name contains. The modifiers are symbols; they include @code{shift},
|
|
@code{control}, and @code{meta}. In addition, a mouse event symbol has
|
|
one of @code{click}, @code{drag}, and @code{down}. For example:
|
|
|
|
@example
|
|
(get 'f5 'event-symbol-elements)
|
|
@result{} (f5)
|
|
(get 'C-f5 'event-symbol-elements)
|
|
@result{} (f5 control)
|
|
(get 'M-S-f5 'event-symbol-elements)
|
|
@result{} (f5 meta shift)
|
|
(get 'mouse-1 'event-symbol-elements)
|
|
@result{} (mouse-1 click)
|
|
(get 'down-mouse-1 'event-symbol-elements)
|
|
@result{} (mouse-1 down)
|
|
@end example
|
|
|
|
Note that the @code{event-symbol-elements} property for a mouse click
|
|
explicitly contains @code{click}, but the event symbol name itself does
|
|
not contain @samp{click}.
|
|
|
|
@item
|
|
Use @code{read-event} to read input if you want to accept any kind of
|
|
event. The old function @code{read-char} now discards events other than
|
|
keyboard characters.
|
|
|
|
@item
|
|
@code{last-command-char} and @code{last-input-char} can now hold any
|
|
kind of event.
|
|
|
|
@item
|
|
The new variable @code{unread-command-events} is much like
|
|
@code{unread-command-char}. Its value is a list of events of any type,
|
|
to be processed as command input in order of appearance in the list.
|
|
|
|
@item
|
|
The function @code{this-command-keys} may return a string or a vector,
|
|
depending on whether or not the sequence read contains only characters.
|
|
You may need to upgrade code which uses this function.
|
|
|
|
The function @code{recent-keys} now returns a vector of events.
|
|
You may need to upgrade code which uses this function.
|
|
|
|
@item
|
|
A keyboard macro's definition can now be either a string or a vector.
|
|
All that really matters is what elements it has. If the elements are
|
|
all characters, then the macro can be a string; otherwise, it has to be
|
|
a vector.
|
|
|
|
@item
|
|
The variable @code{last-event-frame} records which frame the last input
|
|
event was directed to. Usually this is the frame that was selected when
|
|
the event was generated, but if that frame has redirected input focus to
|
|
another frame, @code{last-event-frame} is the frame to which the event
|
|
was redirected.
|
|
|
|
@item
|
|
The interactive specification now allows a new code letter @samp{e} to
|
|
simplify commands bound to events which are lists. This code supplies
|
|
as an argument the complete event object.
|
|
|
|
You can use @samp{e} more than once in a single command's interactive
|
|
specification. If the key sequence which invoked the command has
|
|
@var{n} events with parameters, the @var{n}th @samp{e} provides the
|
|
@var{n}th parameterized event. Events which are not lists, such as
|
|
function keys and ASCII keystrokes, do not count where @samp{e} is
|
|
concerned.
|
|
|
|
@item
|
|
You can extract the starting and ending position values from a mouse
|
|
button or motion event using the two functions @code{event-start} and
|
|
@code{event-end}. These two functions return different values for drag
|
|
and motion events; for click and button-down events, they both return
|
|
the position of the event.
|
|
|
|
@item
|
|
The position, a returned by @code{event-start} and @code{event-end}, is
|
|
a list of this form:
|
|
|
|
@example
|
|
(@var{window} @var{buffer-position} (@var{col} . @var{row}) @var{timestamp})
|
|
@end example
|
|
|
|
You can extract parts of this list with the functions
|
|
@code{posn-window}, @code{posn-point}, @code{posn-col-row}, and
|
|
@code{posn-timestamp}.
|
|
|
|
@item
|
|
The function @code{scroll-bar-scale} is useful for computing where to
|
|
scroll to in response to a mouse button event from a scroll bar. It
|
|
takes two arguments, @var{ratio} and @var{total}, and in effect
|
|
multiplies them. We say ``in effect'' because @var{ratio} is not a
|
|
number; rather a pair @code{(@var{num} . @var{denom}).
|
|
|
|
Here's the usual way to use @code{scroll-bar-scale}:
|
|
|
|
@example
|
|
(scroll-bar-scale (posn-col-row (event-start event))
|
|
(buffer-size))
|
|
@end example
|
|
@end itemize
|
|
|
|
@section Putting Keyboard Events in Strings
|
|
|
|
In most of the places where strings are used, we conceptualize the
|
|
string as containing text characters---the same kind of characters found
|
|
in buffers or files. Occasionally Lisp programs use strings which
|
|
conceptually contain keyboard characters; for example, they may be key
|
|
sequences or keyboard macro definitions. There are special rules for
|
|
how to put keyboard characters into a string, because they are not
|
|
limited to the range of 0 to 255 as text characters are.
|
|
|
|
A keyboard character typed using the @key{META} key is called a
|
|
@dfn{meta character}. The numeric code for such an event includes the
|
|
2**23 bit; it does not even come close to fitting in a string. However,
|
|
earlier Emacs versions used a different representation for these
|
|
characters, which gave them codes in the range of 128 to 255. That did
|
|
fit in a string, and many Lisp programs contain string constants that
|
|
use @samp{\M-} to express meta characters, especially as the argument to
|
|
@code{define-key} and similar functions.
|
|
|
|
We provide backward compatibility to run those programs with special
|
|
rules for how to put a keyboard character event in a string. Here are
|
|
the rules:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If the keyboard event value is in the range of 0 to 127, it can go in the
|
|
string unchanged.
|
|
|
|
@item
|
|
The meta variants of those events, with codes in the range of 2**23 to
|
|
2**23+127, can also go in the string, but you must change their numeric
|
|
values. You must set the 2**7 bit instead of the 2**23 bit, resulting
|
|
in a value between 128 and 255.
|
|
|
|
@item
|
|
Other keyboard character events cannot fit in a string. This includes
|
|
keyboard events in the range of 128 to 255.
|
|
@end itemize
|
|
|
|
Functions such as @code{read-key-sequence} that can construct strings
|
|
containing events follow these rules.
|
|
|
|
When you use the read syntax @samp{\M-} in a string, it produces a
|
|
code in the range of 128 to 255---the same code that you get if you
|
|
modify the corresponding keyboard event to put it in the string. Thus,
|
|
meta events in strings work consistently regardless of how they get into
|
|
the strings.
|
|
|
|
New programs can avoid dealing with these rules by using vectors
|
|
instead of strings for key sequences when there is any possibility that
|
|
these issues might arise.
|
|
|
|
The reason we changed the representation of meta characters as
|
|
keyboard events is to make room for basic character codes beyond 127,
|
|
and support meta variants of such larger character codes.
|
|
|
|
@section Menus
|
|
|
|
You can now define menus conveniently as keymaps. Menus are normally
|
|
used with the mouse, but they can work with the keyboard also.
|
|
|
|
@subsection Defining Menus
|
|
|
|
A keymap is suitable for menu use if it has an @dfn{overall prompt
|
|
string}, which is a string that appears as an element of the keymap. It
|
|
should describes the purpose of the menu. The easiest way to construct
|
|
a keymap with a prompt string is to specify the string as an argument
|
|
when you run @code{make-keymap} or @code{make-sparse-keymap}.
|
|
|
|
The individual bindings in the menu keymap should also have prompt
|
|
strings; these strings are the items in the menu. A binding with a
|
|
prompt string looks like this:
|
|
|
|
@example
|
|
(@var{char} @var{string} . @var{real-binding})
|
|
@end example
|
|
|
|
As far as @code{define-key} is concerned, the string is part of the
|
|
character's binding---the binding looks like this:
|
|
|
|
@example
|
|
(@var{string} . @var{real-binding}).
|
|
@end example
|
|
|
|
However, only @var{real-binding} is used for executing the key.
|
|
|
|
You can also supply a second string, called the help string, as follows:
|
|
|
|
@example
|
|
(@var{char} @var{string} @var{help-string} . @var{real-binding})
|
|
@end example
|
|
|
|
Currently Emacs does not actually use @var{help-string}; it knows only
|
|
how to ignore @var{help-string} in order to extract @var{real-binding}.
|
|
In the future we hope to make @var{help-string} serve as longer
|
|
documentation for the menu item, available on request.
|
|
|
|
The prompt string for a binding should be short---one or two words. Its
|
|
meaning should describe the command it corresponds to.
|
|
|
|
If @var{real-binding} is @code{nil}, then @var{string} appears in the
|
|
menu but cannot be selected.
|
|
|
|
If @var{real-binding} is a symbol, and has a non-@code{nil}
|
|
@code{menu-enable} property, that property is an expression which
|
|
controls whether the menu item is enabled. Every time the keymap is
|
|
used to display a menu, Emacs evaluates the expression, and it enables
|
|
the menu item only if the expression's value is non-@code{nil}. When a
|
|
menu item is disabled, it is displayed in a ``fuzzy'' fashion, and
|
|
cannot be selected with the mouse.
|
|
|
|
@subsection Menus and the Mouse
|
|
|
|
The way to make a menu keymap produce a menu is to make it the
|
|
definition of a prefix key.
|
|
|
|
When the prefix key ends with a mouse event, Emacs handles the menu
|
|
keymap by popping up a visible menu that you can select from with the
|
|
mouse. When you click on a menu item, the event generated is whatever
|
|
character or symbol has the binding which brought about that menu item.
|
|
|
|
A single keymap can appear as multiple panes, if you explicitly
|
|
arrange for this. The way to do this is to make a keymap for each
|
|
pane, then create a binding for each of those maps in the main keymap
|
|
of the menu. Give each of these bindings a prompt string that starts
|
|
with @samp{@@}. The rest of the prompt string becomes the name of the
|
|
pane. See the file @file{lisp/mouse.el} for an example of this. Any
|
|
ordinary bindings with prompt strings are grouped into one pane, which
|
|
appears along with the other panes explicitly created for the
|
|
submaps.
|
|
|
|
You can also get multiple panes from separate keymaps. The full
|
|
definition of a prefix key always comes from merging the definitions
|
|
supplied by the various active keymaps (minor modes, local, and
|
|
global). When more than one of these keymaps is a menu, each of them
|
|
makes a separate pane or panes.
|
|
|
|
@subsection Menus and the Keyboard
|
|
|
|
When a prefix key ending with a keyboard event (a character or function
|
|
key) has a definition that is a menu keymap, you can use the keyboard
|
|
to choose a menu item.
|
|
|
|
Emacs displays the menu alternatives in the echo area. If they don't
|
|
all fit at once, type @key{SPC} to see the next line of alternatives.
|
|
If you keep typing @key{SPC}, you eventually get to the end of the menu
|
|
and then cycle around to the beginning again.
|
|
|
|
When you have found the alternative you want, type the corresponding
|
|
character---the one whose binding is that alternative.
|
|
|
|
In a menu intended for keyboard use, each menu item must clearly
|
|
indicate what character to type. The best convention to use is to make
|
|
the character the first letter of the menu item prompt string. That is
|
|
something users will understand without being told.
|
|
|
|
@subsection The Menu Bar
|
|
|
|
Under X Windows, each frame can have a @dfn{menu bar}---a permanently
|
|
displayed menu stretching horizontally across the top of the frame. The
|
|
items of the menu bar are the subcommands of the fake ``function key''
|
|
@code{menu-bar}, as defined by all the active keymaps.
|
|
|
|
To add an item to the menu bar, invent a fake ``function key'' of your
|
|
own (let's call it @var{key}), and make a binding for the key sequence
|
|
@code{[menu-bar @var{key}]}. Most often, the binding is a menu keymap,
|
|
so that pressing a button on the menu bar item leads to another menu.
|
|
|
|
In order for a frame to display a menu bar, its @code{menu-bar-lines}
|
|
property must be greater than zero. Emacs uses just one line for the
|
|
menu bar itself; if you specify more than one line, the other lines
|
|
serve to separate the menu bar from the windows in the frame. We
|
|
recommend you try one or two as the @code{menu-bar-lines} value.
|
|
|
|
@section Keymaps
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The representation of keymaps has changed to support the new event
|
|
types. All keymaps now have the form @code{(keymap @var{element}
|
|
@var{element} @dots{})}. Each @var{element} takes one of the following
|
|
forms:
|
|
|
|
@table @asis
|
|
@item @var{prompt-string}
|
|
A string as an element of the keymap marks the keymap as a menu, and
|
|
serves as the overal prompt string for it.
|
|
|
|
@item @code{(@var{key} . @var{binding})}
|
|
A cons cell binds @var{key} to @var{definition}. Here @var{key} may be
|
|
any sort of event head---a character, a function key symbol, or a mouse
|
|
button symbol.
|
|
|
|
@item @var{vector}
|
|
A vector of 128 elements binds all the ASCII characters; the @var{n}th
|
|
element holds the binding for character number @var{n}.
|
|
|
|
@item @code{(t . @var{binding})}
|
|
A cons cell whose @sc{car} is @code{t} is a default binding; anything
|
|
not bound by previous keymap elements is given @var{binding} as its
|
|
binding.
|
|
|
|
Default bindings are important because they allow a keymap to bind all
|
|
possible events without having to enumerate all the possible function
|
|
keys and mouse clicks, with all possible modifier prefixes.
|
|
|
|
The function @code{lookup-key} (and likewise other functions for
|
|
examining a key binding) normally report only explicit bindings of the
|
|
specified key sequence; if there is none, they return @code{nil}, even
|
|
if there is a default binding that would apply to that key sequence if
|
|
it were actually typed in. However, these functions now take an
|
|
optional argument @var{accept-defaults} which, if non-@code{nil}, says
|
|
to consider default bindings.
|
|
|
|
Note that if a vector in the keymap binds an ASCII character to
|
|
@code{nil} (thus making it ``unbound''), the default binding does not
|
|
apply to the character. Think of the vector element as an explicit
|
|
binding of @code{nil}.
|
|
|
|
Note also that if the keymap for a minor or major mode contains a
|
|
default binding, it completely masks out any lower-priority keymaps.
|
|
@end table
|
|
|
|
@item
|
|
A keymap can now inherit from another keymap. Do do this, make the
|
|
latter keymap the ``tail'' of the new one. Such a keymap looks like
|
|
this:
|
|
|
|
@example
|
|
(keymap @var{bindings}@dots{} . @var{other-keymap})
|
|
@end example
|
|
|
|
The effect is that this keymap inherits all the bindings of
|
|
@var{other-keymap}, but can add to them or override them with
|
|
@var{bindings}. Subsequent changes in the bindings of
|
|
@var{other-keymap} @emph{do} affect this keymap.
|
|
|
|
For example,
|
|
|
|
@example
|
|
(setq my-mode-map (cons 'keymap text-mode-map))
|
|
@end example
|
|
|
|
@noindent
|
|
makes a keymap that by default inherits all the bindings of Text
|
|
mode---whatever they may be at the time a key is looked up. Any
|
|
bindings made explicitly in @code{my-mode-map} override the bindings
|
|
inherited from Text mode, however.
|
|
|
|
@item
|
|
Minor modes can now have local keymaps. Thus, a key can act a special
|
|
way when a minor mode is in effect, and then revert to the major mode or
|
|
global definition when the minor mode is no longer in effect. The
|
|
precedence of keymaps is now: minor modes (in no particular order), then
|
|
major mode, and lastly the global map.
|
|
|
|
The new @code{current-minor-mode-maps} function returns a list of all
|
|
the keymaps of currently enabled minor modes, in the other that they
|
|
apply.
|
|
|
|
To set up a keymap for a minor mode, add an element to the alist
|
|
@code{minor-mode-map-alist}. Its elements look like this:
|
|
|
|
@example
|
|
(@var{symbol} . @var{keymap})
|
|
@end example
|
|
|
|
The keymap @var{keymap} is active whenever @var{symbol} has a
|
|
non-@code{nil} value. Use for @var{symbol} the variable which indicates
|
|
whether the minor mode is enabled.
|
|
|
|
When more than one minor mode keymap is active, their order of
|
|
precedence is the order of @code{minor-mode-map-alist}. But you should
|
|
design minor modes so that they don't interfere with each other, and if
|
|
you do this properly, the order will not matter.
|
|
|
|
The function @code{minor-mode-key-binding} returns a list of all the
|
|
active minor mode bindings of @var{key}. More precisely, it returns an
|
|
alist of pairs @code{(@var{modename} . @var{binding})}, where
|
|
@var{modename} is the the variable which enables the minor mode, and
|
|
@var{binding} is @var{key}'s definition in that mode. If @var{key} has
|
|
no minor-mode bindings, the value is @code{nil}.
|
|
|
|
If the first binding is a non-prefix, all subsequent bindings from other
|
|
minor modes are omitted, since they would be completely shadowed.
|
|
Similarly, the list omits non-prefix bindings that follow prefix
|
|
bindings.
|
|
|
|
@item
|
|
The new function @code{copy-keymap} copies a keymap, producing a new
|
|
keymap with the same key bindings in it. If the keymap contains other
|
|
keymaps directly, these subkeymaps are copied recursively.
|
|
|
|
If you want to, you can define a prefix key with a binding that is a
|
|
symbol whose function definition is another keymap. In this case,
|
|
@code{copy-keymap} does not look past the symbol; it doesn't copy the
|
|
keymap inside the symbol.
|
|
|
|
@item
|
|
@code{substitute-key-definition} now accepts an optional fourth
|
|
argument, which is a keymap to use as a template.
|
|
|
|
@example
|
|
(substitute-key-definition olddef newdef keymap oldmap)
|
|
@end example
|
|
|
|
@noindent
|
|
finds all characters defined in @var{oldmap} as @var{olddef},
|
|
and defines them in @var{keymap} as @var{newdef}.
|
|
|
|
In addition, this function now operates recursively on the keymaps that
|
|
define prefix keys within @var{keymap} and @var{oldmap}.
|
|
@end itemize
|
|
|
|
@section Minibuffer Features
|
|
|
|
The minibuffer input functions @code{read-from-minibuffer} and
|
|
@code{completing-read} have new features.
|
|
|
|
@subsection Minibuffer History
|
|
|
|
A new optional argument @var{hist} specifies which history list to use.
|
|
If you specify a variable (a symbol), that variable is the history
|
|
list. If you specify a cons cell @code{(@var{variable}
|
|
. @var{startpos})}, then @var{variable} is the history list variable,
|
|
and @var{startpos} specifies the initial history position (an integer,
|
|
counting from zero which specifies the most recent element of the
|
|
history).
|
|
|
|
If you specify @var{startpos}, then you should also specify that element
|
|
of the history as @var{initial-input}, for consistency.
|
|
|
|
If you don't specify @var{hist}, then the default history list
|
|
@code{minibuffer-history} is used. Other standard history lists that
|
|
you can use when appropriate include @code{query-replace-history},
|
|
@code{command-history}, and @code{file-name-history}.
|
|
|
|
The value of the history list variable is a list of strings, most recent
|
|
first. You should set a history list variable to @code{nil} before
|
|
using it for the first time.
|
|
|
|
@code{read-from-minibuffer} and @code{completing-read} add new elements
|
|
to the history list automatically, and provide commands to allow the
|
|
user to reuse items on the list. The only thing your program needs to
|
|
do to use a history list is to initialize it and to pass its name to the
|
|
input functions when you wish. But it is safe to modify the list by
|
|
hand when the minibuffer input functions are not using it.
|
|
|
|
@subsection Other Minibuffer Features
|
|
|
|
The @var{initial} argument to @code{read-from-minibufer} and other
|
|
minibuffer input functions can now be a cons cell @code{(@var{string}
|
|
. @var{position})}. This means to start off with @var{string} in the
|
|
minibuffer, but put the cursor @var{position} characters from the
|
|
beginning, rather than at the end.
|
|
|
|
In @code{read-no-blanks-input}, the @var{initial} argument is now
|
|
optional; if it is omitted, the initial input string is the empty
|
|
string.
|
|
|
|
@section New Features for Defining Commands
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If the interactive specification begins with @samp{@@}, this means to
|
|
select the window under the mouse. This selection takes place before
|
|
doing anything else with the command.
|
|
|
|
You can use both @samp{@@} and @samp{*} together in one command; they
|
|
are processed in order of appearance.
|
|
|
|
@item
|
|
Prompts in an interactive specification can incorporate the values of
|
|
the preceding arguments. Emacs replaces @samp{%}-sequences (as used
|
|
with the @code{format} function) in the prompt with the interactive
|
|
arguments that have been read so far. For example, a command with this
|
|
interactive specification
|
|
|
|
@example
|
|
(interactive "sReplace: \nsReplace %s with: ")
|
|
@end example
|
|
|
|
@noindent
|
|
prompts for the first argument with @samp{Replace: }, and then prompts
|
|
for the second argument with @samp{Replace @var{foo} with: }, where
|
|
@var{foo} is the string read as the first argument.
|
|
|
|
@item
|
|
If a command name has a property @code{enable-recursive-minibuffers}
|
|
which is non-@code{nil}, then the command can use the minibuffer to read
|
|
arguments even if it is invoked from the minibuffer. The minibuffer
|
|
command @code{next-matching-history-element} (normally bound to
|
|
@kbd{M-s} in the minibuffer) uses this feature.
|
|
@end itemize
|
|
|
|
@section New Features for Reading Input
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The function @code{set-input-mode} now takes four arguments. The last
|
|
argument is optional. Their names are @var{interrupt}, @var{flow},
|
|
@var{meta} and @var{quit}.
|
|
|
|
The argument @var{interrupt} says whether to use interrupt-driven
|
|
input. Non-@code{nil} means yes, and @code{nil} means no (use CBREAK
|
|
mode).
|
|
|
|
The argument @var{flow} says whether to enable terminal flow control.
|
|
Non-@code{nil} means yes.
|
|
|
|
The argument @var{meta} says whether to enable the use of a Meta key.
|
|
Non-@code{nil} means yes.
|
|
|
|
If @var{quit} non-@code{nil}, it is the character to use for quitting.
|
|
(Normally this is @kbd{C-g}.)
|
|
|
|
@item
|
|
The variable @code{meta-flag} has been deleted; use
|
|
@code{set-input-mode} to enable or disable support for a @key{META}
|
|
key. This change was made because @code{set-input-mode} can send the
|
|
terminal the appropriate commands to enable or disable operation of the
|
|
@key{META} key.
|
|
|
|
@item
|
|
The new variable @code{extra-keyboard-modifiers} lets Lisp programs
|
|
``press'' the modifier keys on the keyboard.
|
|
The value is a bit mask:
|
|
|
|
@table @asis
|
|
@item 1
|
|
The @key{SHIFT} key.
|
|
@item 2
|
|
The @key{LOCK} key.
|
|
@item 4
|
|
The @key{CTL} key.
|
|
@item 8
|
|
The @key{META} key.
|
|
@end table
|
|
|
|
When you use X windows, the program can press any of the modifier keys
|
|
in this way. Otherwise, only the @key{CTL} and @key{META} keys can be
|
|
virtually pressed.
|
|
|
|
@item
|
|
You can use the new function @code{keyboard-translate} to set up
|
|
@code{keyboard-translate-table} conveniently.
|
|
|
|
@item
|
|
Y-or-n questions using the @code{y-or-n-p} function now accept @kbd{C-]}
|
|
(usually mapped to @code{abort-recursive-edit}) as well as @kbd{C-g} to
|
|
quit.
|
|
|
|
@item
|
|
The variable @code{num-input-keys} is the total number of key sequences
|
|
that the user has typed during this Emacs session.
|
|
|
|
@item
|
|
A new Lisp variable, @code{function-key-map}, holds a keymap which
|
|
describes the character sequences sent by function keys on an ordinary
|
|
character terminal. This uses the same keymap data structure that is
|
|
used to hold bindings of key sequences, but it has a different meaning:
|
|
it specifies translations to make while reading a key sequence.
|
|
|
|
If @code{function-key-map} ``binds'' a key sequence @var{k} to a vector
|
|
@var{v}, then when @var{k} appears as a subsequence @emph{anywhere} in a
|
|
key sequence, it is replaced with @var{v}.
|
|
|
|
For example, VT100 terminals send @kbd{@key{ESC} O P} when the ``keypad''
|
|
PF1 key is pressed. Thus, on a VT100, @code{function-key-map} should
|
|
``bind'' that sequence to @code{[pf1]}. This specifies translation of
|
|
@kbd{@key{ESC} O P} into @key{PF1} anywhere in a key sequence.
|
|
|
|
Thus, typing @kbd{C-c @key{PF1}} sends the character sequence @kbd{C-c
|
|
@key{ESC} O P}, but @code{read-key-sequence} translates this back into
|
|
@kbd{C-c @key{PF1}}, which it returns as the vector @code{[?\C-c PF1]}.
|
|
|
|
Entries in @code{function-key-map} are ignored if they conflict with
|
|
bindings made in the minor mode, local, or global keymaps.
|
|
|
|
The value of @code{function-key-map} is usually set up automatically
|
|
according to the terminal's Terminfo or Termcap entry, and the
|
|
terminal-specific Lisp files. Emacs comes with a number of
|
|
terminal-specific files for many common terminals; their main purpose is
|
|
to make entries in @code{function-key-map} beyond those that can be
|
|
deduced from Termcap and Terminfo.
|
|
|
|
@item
|
|
The variable @code{key-translation-map} works like @code{function-key-map}
|
|
except for two things:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@code{key-translation-map} goes to work after @code{function-key-map} is
|
|
finished; it receives the results of translation by
|
|
@code{function-key-map}.
|
|
|
|
@item
|
|
@code{key-translation-map} overrides actual key bindings.
|
|
@end itemize
|
|
|
|
The intent of @code{key-translation-map} is for users to map one
|
|
character set to another, including ordinary characters normally bound
|
|
to @code{self-insert-command}.
|
|
@end itemize
|
|
|
|
@section New Syntax Table Features
|
|
|
|
@itemize @bullet
|
|
@item
|
|
You can use two new functions to move across characters in certain
|
|
syntax classes.
|
|
|
|
@code{skip-syntax-forward} moves point forward across characters whose
|
|
syntax classes are mentioned in its first argument, a string. It stops
|
|
when it encounters the end of the buffer, or position @var{lim} (the
|
|
optional second argument), or a character it is not supposed to skip.
|
|
The function @code{skip-syntax-backward} is similar but moves backward.
|
|
|
|
@item
|
|
The new function @code{forward-comment} moves point by comments. It
|
|
takes one argument, @var{count}; it moves point forward across
|
|
@var{count} comments (backward, if @var{count} is negative). If it
|
|
finds anything other than a comment or whitespace, it stops, leaving
|
|
point at the far side of the last comment found. It also stops after
|
|
satisfying @var{count}.
|
|
|
|
@item
|
|
The new variable @code{words-include-escapes} affects the behavior of
|
|
@code{forward-word} and everything that uses it. If it is
|
|
non-@code{nil}, then characters in the ``escape'' and ``character
|
|
quote'' syntax classes count as part of words.
|
|
|
|
@item
|
|
There are two new syntax flags for use in syntax tables.
|
|
|
|
@itemize -
|
|
@item
|
|
The prefix flag.
|
|
|
|
The @samp{p} flag identifies additional ``prefix characters'' in Lisp
|
|
syntax. You can set this flag with @code{modify-syntax-entry} by
|
|
including the letter @samp{p} in the syntax specification.
|
|
|
|
These characters are treated as whitespace when they appear between
|
|
expressions. When they appear withing an expression, they are handled
|
|
according to their usual syntax codes.
|
|
|
|
The function @code{backward-prefix-chars} moves back over these
|
|
characters, as well as over characters whose primary syntax class is
|
|
prefix (@samp{'}).
|
|
|
|
@item
|
|
The @samp{b} comment style flag.
|
|
|
|
Emacs can now supports two comment styles simultaneously. (This is for
|
|
the sake of C++.) More specifically, it can recognize two different
|
|
comment-start sequences. Both must share the same first character; only
|
|
the second character may differ. Mark the second character of the
|
|
@samp{b}-style comment start sequence with the @samp{b} flag. You can
|
|
set this flag with @code{modify-syntax-entry} by including the letter
|
|
@samp{b} in the syntax specification.
|
|
|
|
The two styles of comment can have different comment-end sequences. A
|
|
comment-end sequence (one or two characters) applies to the @samp{b}
|
|
style if its first character has the @samp{b} flag set; otherwise, it
|
|
applies to the @samp{a} style.
|
|
|
|
The appropriate comment syntax settings for C++ are as follows:
|
|
|
|
@table @asis
|
|
@item @samp{/}
|
|
@samp{124b}
|
|
@item @samp{*}
|
|
@samp{23}
|
|
@item newline
|
|
@samp{>b}
|
|
@end table
|
|
|
|
Thus @samp{/*} is a comment-start sequence for @samp{a} style, @samp{//}
|
|
is a comment-start sequence for @samp{b} style, @samp{*/} is a
|
|
comment-end sequence for @samp{a} style, and newline is a comment-end
|
|
sequence for @samp{b} style.
|
|
@end itemize
|
|
@end itemize
|
|
|
|
@section The Case Table
|
|
|
|
You can customize case conversion using the new case table feature. A
|
|
case table is a collection of strings that specifies the mapping between
|
|
upper case and lower case letters. Each buffer has its own case table.
|
|
You need a case table if you are using a language which has letters that
|
|
are not standard ASCII letters.
|
|
|
|
A case table is a list of this form:
|
|
|
|
@example
|
|
(@var{downcase} @var{upcase} @var{canonicalize} @var{equivalences})
|
|
@end example
|
|
|
|
@noindent
|
|
where each element is either @code{nil} or a string of length 256. The
|
|
element @var{downcase} says how to map each character to its lower-case
|
|
equivalent. The element @var{upcase} maps each character to its
|
|
upper-case equivalent. If lower and upper case characters are in 1-1
|
|
correspondence, use @code{nil} for @var{upcase}; then Emacs deduces the
|
|
upcase table from @var{downcase}.
|
|
|
|
For some languages, upper and lower case letters are not in 1-1
|
|
correspondence. There may be two different lower case letters with the
|
|
same upper case equivalent. In these cases, you need to specify the
|
|
maps for both directions.
|
|
|
|
The element @var{canonicalize} maps each character to a canonical
|
|
equivalent; any two characters that are related by case-conversion have
|
|
the same canonical equivalent character.
|
|
|
|
The element @var{equivalences} is a map that cyclicly permutes each
|
|
equivalence class (of characters with the same canonical equivalent).
|
|
|
|
You can provide @code{nil} for both @var{canonicalize} and
|
|
@var{equivalences}, in which case both are deduced from @var{downcase}
|
|
and @var{upcase}.
|
|
|
|
Here are the functions for working with case tables:
|
|
|
|
@code{case-table-p} is a predicate that says whether a Lisp object is a
|
|
valid case table.
|
|
|
|
@code{set-standard-case-table} takes one argument and makes that
|
|
argument the case table for new buffers created subsequently.
|
|
@code{standard-case-table} returns the current value of the new buffer
|
|
case table.
|
|
|
|
@code{current-case-table} returns the case table of the current buffer.
|
|
@code{set-case-table} sets the current buffer's case table to the
|
|
argument.
|
|
|
|
@code{set-case-syntax-pair} is a convenient function for specifying a
|
|
pair of letters, upper case and lower case. Call it with two arguments,
|
|
the upper case letter and the lower case letter. It modifies the
|
|
standard case table and a few syntax tables that are predefined in
|
|
Emacs. This function is intended as a subroutine for packages that
|
|
define non-ASCII character sets.
|
|
|
|
Load the library @file{iso-syntax} to set up the syntax and case table for
|
|
the 256 bit ISO Latin 1 character set.
|
|
|
|
@section New Features for Dealing with Buffers
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The new function @code{buffer-modified-tick} returns a buffer's
|
|
modification-count that ticks every time the buffer is modified. It
|
|
takes one optional argument, which is the buffer you want to examine.
|
|
If the argument is @code{nil} (or omitted), the current buffer is used.
|
|
|
|
@item
|
|
@code{buffer-disable-undo} is a new name for the function
|
|
formerly known as @code{buffer-flush-undo}. This turns off recording
|
|
of undo information in the buffer given as argument.
|
|
|
|
@item
|
|
The new function @code{generate-new-buffer-name} chooses a name that
|
|
would be unique for a new buffer---but does not create the buffer. Give
|
|
it one argument, a starting name. It produces a name not in use for a
|
|
buffer by appending a number inside of @samp{<@dots{}>}.
|
|
|
|
@item
|
|
The function @code{rename-buffer} now takes an option second argument
|
|
which tells it that if the specified new name corresponds to an existing
|
|
buffer, it should use @code{generate-new-buffer-name} to modify the name
|
|
to be unique, rather than signaling an error.
|
|
|
|
@code{rename-buffer} now returns the name to which the buffer was
|
|
renamed.
|
|
|
|
@item
|
|
The function @code{list-buffers} now looks at the local variable
|
|
@code{list-buffers-directory} in each non-file-visiting buffer, and
|
|
shows its value where the file would normally go. Dired sets this
|
|
variable in each Dired buffer, so the buffer list now shows which
|
|
directory each Dired buffer is editing.
|
|
|
|
@item
|
|
The function @code{other-buffer} now takes an optional second argument
|
|
@var{visible-ok} which, if non-@code{nil}, indicates that buffers
|
|
currently being displayed in windows may be returned even if there are
|
|
other buffers not visible. Normally, @code{other-buffer} returns a
|
|
currently visible buffer only as a last resort, if there are no suitable
|
|
nonvisible buffers.
|
|
|
|
@item
|
|
The hook @code{kill-buffer-hook} now runs whenever a buffer is killed.
|
|
@end itemize
|
|
|
|
@section Local Variables Features
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If a local variable name has a non-@code{nil} @code{permanent-local}
|
|
property, then @code{kill-all-local-variables} does not kill it. Such
|
|
local variables are ``permanent''---they remain unchanged even if you
|
|
select a different major mode.
|
|
|
|
Permanent locals are useful when they have to do with where the file
|
|
came from or how to save it, rather than with how to edit the contents.
|
|
|
|
@item
|
|
The function @code{make-local-variable} now never changes the value of the variable
|
|
that it makes local. If the variable had no value before, it still has
|
|
no value after becoming local.
|
|
|
|
@item
|
|
The new function @code{default-boundp} tells you whether a variable has
|
|
a default value (as opposed to being unbound in its default value). If
|
|
@code{(default-boundp 'foo)} returns @code{nil}, then
|
|
@code{(default-value 'foo)} would get an error.
|
|
|
|
@code{default-boundp} is to @code{default-value} as @code{boundp} is to
|
|
@code{symbol-value}.
|
|
|
|
@item
|
|
The special forms @code{defconst} and @code{defvar}, when the variable
|
|
is local in the current buffer, now set the variable's default value
|
|
rather than its local value.
|
|
@end itemize
|
|
|
|
@section New Features for Subprocesses
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@code{call-process} and @code{call-process-region} now return a value
|
|
that indicates how the synchronous subprocess terminated. It is either
|
|
a number, which is the exit status of a process, or a signal name
|
|
represented as a string.
|
|
|
|
@item
|
|
@code{process-status} now returns @code{open} and @code{closed} as the
|
|
status values for network connections.
|
|
|
|
@item
|
|
The standard asynchronous subprocess features work on VMS now,
|
|
and the special VMS asynchronous subprocess functions have been deleted.
|
|
|
|
@item
|
|
You can use the transaction queue feature for more convenient
|
|
communication with subprocesses using transactions.
|
|
|
|
Call @code{tq-create} to create a transaction queue communicating with a
|
|
specified process. Then you can call @code{tq-enqueue} to send a
|
|
transaction. @code{tq-enqueue} takes these five arguments:
|
|
|
|
@example
|
|
(tq-enqueue @var{tq} @var{question} @var{regexp} @var{closure} @var{fn})
|
|
@end example
|
|
|
|
@var{tq} is the queue to use. (Specifying the queue has the effect of
|
|
specifying the process to talk to.) The argument @var{question} is the
|
|
outgoing message which starts the transaction. The argument @var{fn} is
|
|
the function to call when the corresponding answer comes back; it is
|
|
called with two arguments: @var{closure}, and the answer received.
|
|
|
|
The argument @var{regexp} is a regular expression to match the entire
|
|
answer; that's how @code{tq-enqueue} tells where the answer ends.
|
|
|
|
Call @code{tq-close} to shut down a transaction queue and terminate its
|
|
subprocess.
|
|
|
|
@item
|
|
The function @code{signal-process} sends a signal to process @var{pid},
|
|
which need not be a child of Emacs. The second argument @var{signal}
|
|
specifies which signal to send; it should be an integer.
|
|
@end itemize
|
|
|
|
@section New Features for Dealing with Times And Time Delays
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The new function @code{current-time} returns the system's time value as
|
|
a list of three integers: @code{(@var{high} @var{low} @var{microsec})}.
|
|
The integers @var{high} and @var{low} combine to give the number of
|
|
seconds since 0:00 January 1, 1970, which is @var{high} * 2**16 +
|
|
@var{low}.
|
|
|
|
@var{microsec} gives the microseconds since the start of the current
|
|
second (or 0 for systems that return time only on the resolution of a
|
|
second).
|
|
|
|
@item
|
|
The function @code{current-time-string} accepts an optional argument
|
|
@var{time-value}. If given, this specifies a time to format instead of
|
|
the current time. The argument should be a cons cell containing two
|
|
integers, or a list whose first two elements are integers. Thus, you
|
|
can use times obtained from @code{current-time} (see above) and from
|
|
@code{file-attributes}.
|
|
|
|
@item
|
|
You can now find out the user's time zone using @code{current-time-zone}.
|
|
It takes no arguments, and returns a list of this form:
|
|
|
|
@example
|
|
(@var{offset} @var{savings-flag} @var{standard} @var{savings})
|
|
@end example
|
|
|
|
@var{offset} is an integer specifying how many minutes east of Greenwich
|
|
the current time zone is located. A negative value means west of
|
|
Greenwich. Note that this describes the standard time; if daylight
|
|
savings time is in effect, it does not affect this value.
|
|
|
|
@var{savings-flag} is non-@code{nil} iff daylight savings time or some other
|
|
sort of seasonal time adjustment is in effect.
|
|
|
|
@var{standard} is a string giving the name of the time zone when no
|
|
seasonal time adjustment is in effect.
|
|
|
|
@var{savings} is a string giving the name of the time zone when there is a
|
|
seasonal time adjustment in effect.
|
|
|
|
If the user has specified a region that does not use a seasonal time
|
|
adjustment, @var{savings-flag} is always @code{nil}, and @var{standard}
|
|
and @var{savings} are equal.
|
|
|
|
@item
|
|
@code{sit-for}, @code{sleep-for} now let you specify the time period in
|
|
milliseconds as well as in seconds. The first argument gives the number
|
|
of seconds, as before, and the optional second argument gives additional
|
|
milliseconds. The time periods specified by these two arguments are
|
|
added together.
|
|
|
|
Not all systems support this; you get an error if you specify nonzero
|
|
milliseconds and it isn't supported.
|
|
|
|
@code{sit-for} also accepts an optional third argument @var{nodisp}. If
|
|
this is non-@code{nil}, @code{sit-for} does not redisplay. It still
|
|
waits for the specified time or until input is available.
|
|
|
|
@item
|
|
@code{accept-process-output} now accepts a timeout specified by optional
|
|
second and third arguments. The second argument specifies the number of
|
|
seconds, while the third specifies the number of milliseconds. The time
|
|
periods specified by these two arguments are added together.
|
|
|
|
Not all systems support this; you get an error if you specify nonzero
|
|
milliseconds and it isn't supported.
|
|
|
|
The function returns @code{nil} if the timeout expired before output
|
|
arrived, or non-@code{nil} if it did get some output.
|
|
|
|
@item
|
|
You can set up a timer to call a function at a specified future time.
|
|
To do so, call @code{run-at-time}, like this:
|
|
|
|
@example
|
|
(run-at-time @var{time} @var{repeat} @var{function} @var{args}@dots{})
|
|
@end example
|
|
|
|
Here, @var{time} is a string saying when to call the function. The
|
|
argument @var{function} is the function to call later, and @var{args}
|
|
are the arguments to give it when it is called.
|
|
|
|
The argument @var{repeat} specifies how often to repeat the call. If
|
|
@var{repeat} is @code{nil}, there are no repetitions; @var{function} is
|
|
called just once, at @var{time}. If @var{repeat} is an integer, it
|
|
specifies a repetition period measured in seconds.
|
|
|
|
Absolute times may be specified in a wide variety of formats; The form
|
|
@samp{@var{hour}:@var{min}:@var{sec} @var{timezone}
|
|
@var{month}/@var{day}/@var{year}}, where all fields are numbers, works;
|
|
the format that @code{current-time-string} returns is also allowed.
|
|
|
|
To specify a relative time, use numbers followed by units.
|
|
For example:
|
|
|
|
@table @samp
|
|
@item 1 min
|
|
denotes 1 minute from now.
|
|
@item 1 min 5 sec
|
|
denotes 65 seconds from now.
|
|
@item 1 min 2 sec 3 hour 4 day 5 week 6 fortnight 7 month 8 year
|
|
denotes exactly 103 months, 123 days, and 10862 seconds from now.
|
|
@end table
|
|
|
|
If @var{time} is an integer, that specifies a relative time measured in
|
|
seconds.
|
|
@end itemize
|
|
|
|
To cancel the requested future action, pass the value that @code{run-at-time}
|
|
returned to the function @code{cancel-timer}.
|
|
|
|
@section Profiling Lisp Programs
|
|
|
|
You can now make execution-time profiles of Emacs Lisp programs using
|
|
the @file{profile} library. See the file @file{profile.el} for
|
|
instructions; if you have written a Lisp program big enough to be worth
|
|
profiling, you can surely understand them.
|
|
|
|
@section New Features for Lisp Debuggers
|
|
|
|
@itemize @bullet
|
|
@item
|
|
You can now specify which kinds of errors should invoke the Lisp
|
|
debugger by setting the variable @code{debug-on-error} to a list of error
|
|
conditions. For example, if you set it to the list @code{(void-variable)},
|
|
then only errors about a variable that has no value invoke the
|
|
debugger.
|
|
|
|
@item
|
|
The variable @code{command-debug-status} is used by Lisp debuggers. It
|
|
records the debugging status of current interactive command. Each time
|
|
a command is called interactively, this variable is bound to
|
|
@code{nil}. The debugger can set this variable to leave information for
|
|
future debugger invocations during the same command.
|
|
|
|
The advantage of this variable over some other variable in the debugger
|
|
itself is that the data will not be visible for any other command
|
|
invocation.
|
|
|
|
@item
|
|
The function @code{backtrace-frame} is intended for use in Lisp
|
|
debuggers. It returns information about what a frame on the Lisp call
|
|
stack is doing. You specify one argument, which is the number of stack
|
|
frames to count up from the current execution point.
|
|
|
|
If that stack frame has not evaluated the arguments yet (or is a special
|
|
form), the value is @code{(nil @var{function} @var{arg-forms}@dots{})}.
|
|
|
|
If that stack frame has evaluated its arguments and called its function
|
|
already, the value is @code{(t @var{function}
|
|
@var{arg-values}@dots{})}.
|
|
|
|
In the return value, @var{function} is whatever was supplied as @sc{car}
|
|
of evaluated list, or a @code{lambda} expression in the case of a macro
|
|
call. If the function has a @code{&rest} argument, that is represented
|
|
as the tail of the list @var{arg-values}.
|
|
|
|
If the argument is out of range, @code{backtrace-frame} returns
|
|
@code{nil}.
|
|
@end itemize
|
|
|
|
@ignore
|
|
|
|
@item
|
|
@code{kill-ring-save} now gives visual feedback to indicate the region
|
|
of text being added to the kill ring. If the opposite end of the
|
|
region is visible in the current window, the cursor blinks there.
|
|
Otherwise, some text from the other end of the region is displayed in
|
|
the message area.
|
|
@end ignore
|
|
|
|
@section Memory Allocation Changes
|
|
|
|
The list that @code{garbage-collect} returns now has one additional
|
|
element. This is a cons cell containing two numbers. It gives
|
|
information about the number of used and free floating point numbers,
|
|
much as the first element gives such information about the number of
|
|
used and free cons cells.
|
|
|
|
The new function @code{memory-limit} returns an indication of the last
|
|
address allocated by Emacs. More precisely, it returns that address
|
|
divided by 1024. You can use this to get a general idea of how your
|
|
actions affect the memory usage.
|
|
|
|
@section Hook Changes
|
|
|
|
@itemize @bullet
|
|
@item
|
|
Expanding an abbrev first runs the new hook
|
|
@code{pre-abbrev-expand-hook}.
|
|
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@item
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The editor command loop runs the normal hook @code{pre-command-hook}
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before each command, and runs @code{post-command-hook} after each
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command.
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@item
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Auto-saving runs the new hook @code{auto-save-hook} before actually
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starting to save any files.
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@item
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The new variable @code{revert-buffer-insert-file-contents-function}
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|
holds a function that @code{revert-buffer} now uses to read in the
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|
contents of the reverted buffer---instead of calling
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|
@code{insert-file-contents}.
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@item
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The variable @code{lisp-indent-hook} has been renamed to
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|
@code{lisp-indent-function}.
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@item
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|
The variable @code{auto-fill-hook} has been renamed to
|
|
@code{auto-fill-function}.
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|
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@item
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|
The variable @code{blink-paren-hook} has been renamed to
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|
@code{blink-paren-function}.
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|
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@item
|
|
The variable @code{temp-buffer-show-hook} has been renamed to
|
|
@code{temp-buffer-show-function}.
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|
|
|
@item
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|
The variable @code{suspend-hook} has been renamed to
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|
@code{suspend-hooks}, because it is a list of functions but is not a
|
|
normal hook.
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|
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@item
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|
The new function @code{add-hook} provides a handy way to add a function
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|
to a hook variable. For example,
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|
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@example
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|
(add-hook 'text-mode-hook 'my-text-hook-function)
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@end example
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@noindent
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|
arranges to call @code{my-text-hook-function}
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|
when entering Text mode or related modes.
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@end itemize
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@bye
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