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447 lines
16 KiB
Plaintext
@c -*-texinfo-*-
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@c This is part of the GNU Emacs Lisp Reference Manual.
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@c Copyright (C) 1999, 2002, 2003, 2004, 2005,
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@c 2006 Free Software Foundation, Inc.
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@c See the file elisp.texi for copying conditions.
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@c This node must have no pointers.
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@node Antinews, GNU Free Documentation License, System Interface, Top
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@appendix Emacs 21 Antinews
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For those users who live backwards in time, here is information about
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downgrading to Emacs version 21.4. We hope you will enjoy the greater
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simplicity that results from the absence of many Emacs @value{EMACSVER}
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features.
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@section Old Lisp Features in Emacs 21
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@itemize @bullet
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@item
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Many unnecessary features of redisplay have been eliminated. (The
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earlier major release, Emacs 20, will have a completely rewritten
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redisplay engine, which will be even simpler.)
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@itemize @minus
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@item
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The function @code{force-window-update} has been removed. It
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shouldn't be needed, since changes in window contents are detected
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automatically. In case they aren't, call @code{redraw-display} to
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redraw everything.
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@item
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Point no longer moves out from underneath invisible text at the end of
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each command. This allows the user to detect invisible text by moving
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the cursor around---if the cursor gets stuck, there is something
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invisible in the way. If you really want cursor motion to ignore the
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text, try marking it as intangible.
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@item
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Support for image maps and image slices has been removed. Emacs was
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always meant for editing text, anyway.
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@item
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The mode line now accepts all text properties, as well as
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@code{:propertize} and @code{:eval} forms, regardless of the
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@code{risky-local-variable} property.
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@item
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The @code{line-height} and @code{line-spacing} properties no longer
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have any meaning for newline characters. Such properties wouldn't
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make sense, since newlines are not really characters; they just tell
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you where to break a line.
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@item
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Considerable simplifications have been made to the display
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specification @code{(space . @var{props})}, which is used for
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displaying a space of specified width and height. Pixel-based
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specifications and Lisp expressions are no longer accepted.
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@item
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Many features associated with the fringe areas have been removed, to
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encourage people to concentrate on the main editing area (the fringe
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will be completely removed in Emacs 20.) Arbitrary bitmaps can no
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longer be displayed in the fringe; an overlay arrow can still be
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displayed, but there can only be one overlay arrow at a time (any more
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would be confusing.) The fringe widths cannot be adjusted, and
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individual windows cannot have their own fringe settings. A mouse
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click on the fringe no longer generates a special event.
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@item
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Individual windows cannot have their own scroll-bar settings.
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@item
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You can no longer use @samp{default} in a @code{defface} to specify
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defaults for subsequent faces.
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@item
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The function @code{display-supports-face-attributes-p} has been
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removed. In @code{defface} specifications, the @code{supports}
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predicate is no longer supported.
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@item
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@code{face-attribute-relative-p} and @code{merge-face-attribute} have
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been removed.
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@item
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The priority of faces in a list supplied by the @code{:inherit} face
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attribute has been reversed. We like to make changes like this once
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in a while, to keep Emacs Lisp programmers on their toes.
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@item
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The @code{min-colors} face attribute, used for tailoring faces to
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limited-color displays, does not exist. If in doubt, use colors like
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``white'' and ``black'', which ought to be defined everywhere.
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@item
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The @code{tty-color-mode} frame parameter does not exist. You should
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just trust the terminal capabilities database.
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@end itemize
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@item
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Several simplifications have been made to mouse support:
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@itemize @minus
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@item
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Clicking @kbd{mouse-1} won't follow links, as that is alien to the
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spirit of Emacs. Therefore, the @code{follow-link} property doesn't
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has any special meaning, and the function @code{mouse-on-link-p} has
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been removed.
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@item
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The variable @code{void-text-area-pointer} has been removed, so the
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mouse pointer shape remains unchanged when moving between valid text
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areas and void text areas. The @code{pointer} image and text
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properties are no longer supported.
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@item
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Mouse events will no longer specify the timestamp, the object clicked,
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equivalent buffer positions (for marginal or fringe areas), glyph
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coordinates, or relative pixel coordinates.
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@end itemize
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@item
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Simplifications have also been made to the way Emacs handles keymaps
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and key sequences:
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@itemize @minus
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@item
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The @code{kbd} macro has been removed. It isn't that difficult to
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write key sequences using the string and vector representations, and
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we want to encourage users to learn.
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@item
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Emacs no longer supports key remapping. You can do pretty much the
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same thing with @code{substitute-key-definition}, or by advising the
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relevant command.
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@item
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The @code{keymap} text and overlay property is now overridden by minor
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mode keymaps, and will not work at the ends of text properties and
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overlays.
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@item
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The functions @code{map-keymap}, @code{keymap-prompt}, and
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@code{current-active-maps} have been removed.
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@end itemize
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@item
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Process support has been pared down to a functional minimum. The
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functions @code{call-process-shell-command} and @code{process-file}
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have been deleted. Processes no longer maintain property lists, and
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they won't ask any questions when the user tries to exit Emacs (which
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would simply be rude.) The function @code{signal-process} won't
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accept a process object, only the process id; determining the process
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id from a process object is left as an exercise to the programmer.
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@item
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Networking has also been simplified: @code{make-network-process} and
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its various associated function have all been replaced with a single
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easy-to-use function, @code{open-network-stream}, which can't use UDP,
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can't act as a server, and can't set up non-blocking connections.
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Also, deleting a network process with @code{delete-process} won't call
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the sentinel.
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@item
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Many programming shortcuts have been deleted, to provide you with the
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enjoyment of ``rolling your own''. The macros @code{while-no-input},
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@code{with-local-quit}, and @code{with-selected-window}, along with
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@code{dynamic-completion-table} and @code{lazy-completion-table} no
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longer exist. Also, there are no built-in progress reporters;
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with Emacs, you can take progress for granted.
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@item
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Variable aliases are no longer supported. Aliases are for functions,
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not for variables.
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@item
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The variables @code{most-positive-fixnum} and
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@code{most-negative-fixnum} do not exist. On 32 bit machines, the
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most positive integer is probably 134217727, and the most negative
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integer is probably -134217728.
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@item
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The functions @code{eql} and @code{macroexpand-all} are no longer
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available. However, you can find similar functions in the @code{cl}
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package.
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@item
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The list returned by @code{split-string} won't include null substrings
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for separators at the beginning or end of a string. If you want to
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check for such separators, do it separately.
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@item
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The function @code{assoc-string} has been removed. Use
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@code{assoc-ignore-case} or @code{assoc-ignore-representation} (which
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are no longer obsolete.)
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@item
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The escape sequence @samp{\s} is always interpreted as a super
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modifier, never a space.
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@item
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The variable @code{buffer-save-without-query} has been removed, to
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prevent Emacs from sneakily saving buffers. Also, the hook
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@code{before-save-hook} has been removed, so if you want something to
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be done before saving, advise or redefine @code{basic-save-buffer}.
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@item
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The variable @code{buffer-auto-save-file-format} has been renamed to
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@code{auto-save-file-format}, and is no longer a permanent local.
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@item
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The function @code{visited-file-modtime} now returns a cons, instead
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of a list of two integers. The primitive @code{set-file-times} has
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been eliminated.
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@item
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The function @code{file-remote-p} is no longer available.
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@item
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When determining the filename extension, a leading dot in a filename
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is no longer ignored. Thus, @file{.emacs} is considered to have
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extension @file{emacs}, rather than being extensionless.
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@item
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Emacs looks for special file handlers in a more efficient manner: it
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will choose the first matching handler in
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@code{file-name-handler-alist}, rather than trying to figure out which
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provides the closest match.
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@item
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The @code{predicate} argument for @code{read-file-name} has been
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removed, and so have the variables @code{read-file-name-function} and
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@code{read-file-name-completion-ignore-case}. The function
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@code{read-directory-name} has also been removed.
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@item
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The functions @code{all-completions} and @code{try-completion} will no
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longer accept lists of strings or hash tables (it will still accept
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alists, obarrays, and functions.) In addition, the function
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@code{test-completion} is no longer available.
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@item
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The @samp{G} interactive code character is no longer supported.
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Use @samp{F} instead.
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@item
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Arbitrary Lisp functions can no longer be recorded into
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@code{buffer-undo-list}. As a consequence, @code{yank-undo-function}
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is obsolete, and has been removed.
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@item
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Emacs will never complain about commands that accumulate too much undo
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information, so you no longer have to worry about binding
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@code{buffer-undo-list} to @code{t} for such commands (though you may
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want to do that anyway, to avoid taking up unnecessary memory space.)
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@item
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Atomic change groups are no longer supported.
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@item
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The list returned by @code{(match-data t)} no longer records the
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buffer as a final element.
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@item
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The function @code{looking-back} has been removed, so we no longer
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have the benefit of hindsight.
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@item
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The variable @code{search-spaces-regexp} does not exist. Spaces
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always stand for themselves in regular expression searches.
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@item
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The functions @code{skip-chars-forward} and @code{skip-chars-backward}
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no longer accepts character classes such as @samp{[:alpha:]}. All
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characters are created equal.
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@item
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The @code{yank-handler} text property no longer has any meaning.
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Also, @code{yank-excluded-properties}, @code{insert-for-yank}, and
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@code{insert-buffer-substring-as-yank} have all been removed.
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@item
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The variable @code{char-property-alias-alist} has been deleted.
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Aliases are for functions, not for properties.
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@item
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The function @code{get-char-property-and-overlay} has been deleted.
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If you want the properties at a point, find the text properties at the
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point; then, find the overlays at the point, and find the properties
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on those overlays.
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@item
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Font Lock mode only manages @code{face} properties; you can't use
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font-lock keywords to specify arbitrary text properties for it to
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manage. After all, it is called Font Lock mode, not Arbitrary
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Properties Lock mode.
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@item
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The arguments to @code{remove-overlays} are no longer optional.
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@item
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In @code{replace-match}, the replacement text now inherits properties
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from the surrounding text.
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@item
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@code{mode-line-format} no longer supports the @code{:propertize},
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@code{%i}, and @code{%I} constructs. The function
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@code{format-mode-line} has been removed.
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@item
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The functions @code{window-inside-edges} and @code{window-body-height}
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have been removed. You should do the relevant calculations yourself,
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starting with @code{window-width} and @code{window-height}.
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@item
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The functions @code{window-pixel-edges} and
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@code{window-inside-pixel-edges} have been removed. We prefer to
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think in terms of lines and columns, not pixel coordinates. (Sometime
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in the distant past, we will do away with graphical terminals
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entirely, in favor of text terminals.) For similar reasons, the
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functions @code{posn-at-point}, @code{posn-at-x-y}, and
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@code{pos-visible-in-window-p} have been removed.
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@item
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The macro @code{save-selected-window} only saves the selected window
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of the selected frame, so don't try selecting windows in other frames.
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@item
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The function @code{minibufferp} is no longer available.
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@item
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The function @code{modify-all-frames-parameters} has been removed (we
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always suspected the name was ungrammatical, anyway.)
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@item
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The @code{line-spacing} variable no longer accepts float values.
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@item
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The function @code{tool-bar-local-item-from-menu} has been deleted.
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If you need to make an entry in the tool bar, you can still use
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@code{tool-bar-add-item-from-menu}, but that modifies the binding in
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the source keymap instead of copying it into the local keymap.
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@item
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When determining the major mode, the file name takes precedence over
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the interpreter magic line. The variable @code{magic-mode-alist},
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which associates certain buffer beginnings with major modes, has been
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eliminated.
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@item
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The hook @code{after-change-major-mode-hook} is not defined, and
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neither are @code{run-mode-hooks} and @code{delay-mode-hooks}.
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@item
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The variable @code{minor-mode-list} has been removed.
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@item
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@code{define-derived-mode} will copy abbrevs from the parent mode's
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abbrev table, instead of creating a new, empty abbrev table.
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@item
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There are no ``system'' abbrevs. When the user saves into the abbrevs
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file, all abbrevs are saved.
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@item
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The Warnings facility has been removed. Just use @code{error}.
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@item
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Several hook variables have been renamed to flout the Emacs naming
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conventions. We feel that consistency is boring, and having
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non-standard hook names encourages users to check the documentation
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before using a hook. For instance, the normal hook
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@code{find-file-hook} has been renamed to @code{find-file-hooks}, and
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the abnormal hook @code{delete-frame-functions} has been renamed to
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@code{delete-frame-hook}.
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@item
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The function @code{symbol-file} does not exist. If you want to know
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which file defined a function or variable, try grepping for it.
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@item
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The variable @code{load-history} records function definitions just
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like variable definitions, instead of indicating which functions were
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previously autoloaded.
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@item
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There is a new variable, @code{recursive-load-depth-limit}, which
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specifies how many times files can recursively load themselves; it is
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50 by default, and @code{nil} means infinity. Previously, Emacs signaled an
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error after just 3 recursive loads, which was boring.
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@item
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Byte-compiler warnings and error messages will leave out the line and
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character positions, in order to exercise your debugging skills.
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Also, there is no @code{with-no-warnings} macro---instead of
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suppressing compiler warnings, fix your code to avoid them!
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@item
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The function @code{unsafep} has been removed.
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@item
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File local variables can now specify a string with text properties.
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Since arbitrary Lisp expressions can be embedded in text properties,
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this can provide you with a great deal of flexibility and power. On
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the other hand, @code{safe-local-eval-forms} and the
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@code{safe-local-eval-function} function property have no special
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meaning.
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@item
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You can no longer use @code{char-displayable-p} to test if Emacs can
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display a certain character.
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@item
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The function @code{string-to-multibyte} is no longer available.
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@item
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The @code{translation-table-for-input} translation table has been
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removed. Also, translation hash tables are no longer available, so we
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don't need the functions @code{lookup-character} and
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@code{lookup-integer}.
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@item
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The @code{table} argument to @code{translate-region} can no longer be
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a char-table; it has to be a string.
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@item
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The functions @code{merge-coding-systems} and
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@code{decode-coding-inserted-region}, and the variable
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@code{auto-coding-functions}, have been deleted. The
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@code{mime-text-unsuitable} coding system property no longer has any
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special meaning.
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@item
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If pure storage overflows while dumping, Emacs won't tell you how much
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additional pure storage it needs. Try adding in increments of 20000,
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until you have enough.
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@item
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The variables @code{gc-elapsed}, @code{gcs-done}, and
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@code{post-gc-hook} have been garbage-collected.
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@end itemize
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@ignore
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arch-tag: 1d0ef137-2bad-430e-ae8e-d820d569b5a6
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@end ignore
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