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296 lines
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296 lines
9.4 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 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 20 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 20.4. We hope you will enjoy the greater
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simplicity that results from the absence of many Emacs 21 features. In
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the following section, we carry this information back to Emacs
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20.3, for which the previous printed edition of this manual was made.
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@section Old Lisp Features in Emacs 20
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@itemize @bullet
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@item
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The @code{push} and @code{pop} macros are not defined.
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Neither are @code{dolist} and @code{dotimes}.
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@item
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You can't display images in buffers. (Emacs is meant for editing text.)
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With no images, there are no display margins, and no tool bars.
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@item
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The @code{display} text property has no special meaning; you can use it
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freely in Lisp programs, with no effects except what you implement for
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yourself. With no images, who needs the @code{display} text property?
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@item
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The @code{field} text property has no special meaning; buffers are no
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longer subdivided into fields. (The division of information into
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fields is always rather arbitrary.)
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@item
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Faces have fewer attributes. The attributes @code{:family},
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@code{:height}, @code{:width}, @code{:weight}, and @code{:slant},
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have been replaced with a font name, a ``bold'' flag, and an
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``italic'' flag.
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The attributes @code{:overline}, @code{:strike-through} and @code{:box}
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have been eliminated too. Underlining now always has the same color as
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the text---using any other color would be bad taste.
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With fewer font attributes, there are no functions
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@code{set-face-attribute} and @code{face-attribute}. Instead, you
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access these attributes using functions such as @code{face-font}, and
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set them with functions such as @code{set-face-font}. (These functions
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were available in Emacs 21, but are not as useful there.)
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@item
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The standard faces @code{scroll-bar}, @code{menu}, @code{border},
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@code{cursor}, and @code{mouse} have been eliminated. They are rather
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strange, as faces, and therefore shouldn't really exist. You can use
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@code{set-border-color}, @code{set-cursor-color} and
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@code{set-mouse-color} to specify the colors for the frame border, the
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text cursor, and the mouse cursor. To specify menu colors, use X
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resources.
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@item
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Colors and other face attributes are no longer supported on character
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terminals, so you no longer have to worry about terminals making faces
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at you.
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@item
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Emacs will respect your peace and quiet, aside from occasional beeps,
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because there are no facilities for playing sounds.
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@item
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Emacs 20 provides a complex and badly designed method for handling
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character composition for languages such as Thai that display several
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letters as a single combined image. We are too ashamed of it to tell
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you any more than that.
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@item
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@code{delete-and-extract-region} has been deleted; instead, use
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@code{buffer-substring} to extract the text, then use
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@code{delete-region} to delete it.
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@item
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Regular expressions do not support the POSIX character classes
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such as @samp{[:alpha:]}. All characters are created equal.
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@item
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Hash tables have been eliminated; use alists instead.
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@item
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The Lisp printer does not detect and report circular structure. That is
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ok, because the Lisp reader cannot recreate circular structure anyway.
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However, there is a library @samp{cust-print.el} which can report
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circular structure.
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@item
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Emacs provides its own implementation of scroll bars, instead
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of using those of the X toolkit. They always use the frame foreground
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and background colors, so you cannot specify different colors for
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the scroll bars.
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@item
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For simplicity, all @sc{ascii} characters now have the same height and width.
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(Certain characters, such as Chinese characters, always have twice
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the standard width.) All characters are created equal.
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@item
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You can now resize any Emacs window, and size changes in one window can
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propagate to all others. Windows can no longer use
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@code{window-size-fixed} to get special privileges.
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@item
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The function @code{intern-soft} no longer accepts a symbol as argument.
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@item
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The function @code{bitmap-spec-p} has been renamed to
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@code{pixmap-spec-p} to encourage users to practice Emacs' help system
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while trying to find it.
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@item
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Tooltips operate using ordinary Emacs frames.
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@item
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Areas of the mode line are not mouse-sensitive; however, some mouse
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commands are available for the mode line as a whole.
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@item
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Windows cannot have header lines. Conversely, there is no way to turn
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off the mode line of a window unless it is a minibuffer.
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@item
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Plain dashes are the only separators you can use in a menu.
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@item
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Vertical fractional scrolling does not exist.
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@item
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The functions @code{format} and @code{message} ignore and discard text
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properties.
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@item
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The function @code{propertize} does not exist;
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you can get the job done using @code{set-text-properties}.
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@item
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Colors are supported only on window systems, not on text-only terminals.
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So the support functions for colors on text-only terminals are
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not needed, and have been eliminated.
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@item
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The functions @code{color-values}, @code{color-defined-p} and
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@code{defined-colors} have been renamed to @code{x-color-values},
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@code{x-color-defined-p} and @code{x-defined-colors}.
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@item
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Windows cannot be made fixed-width or fixed-height;
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Emacs will adjust the size of all windows when it needs to.
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@item
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The string used as the value of the @code{before-string} or
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@code{after-string} property must contain only characters that display
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as a single column---control characters, including tabs and newlines,
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will give strange results.
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@item
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The minibuffer prompt does not actually appear in content of the
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minibuffer; it is displayed specially in the minibuffer window.
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@item
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The ``exclusive open'' feature of @code{write-region}
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has been eliminated; any non-@code{nil} value for the seventh
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argument now means to ask the user for confirmation.
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@item
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The function @code{buffer-size} always reports on the
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current buffer.
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@item
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The function @code{assq-delete-all} has itself been deleted.
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So there!
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@item
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The keyword @code{:set-after} no longer does anything in
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@code{defcustom}.
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@item
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The variable @code{small-temporary-file-directory} has no special
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meaning. There's only one variable for specifying which directory to
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use for temporary files, @code{temporary-file-directory}, but not all
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Emacs features use it anyway. Some use the @code{TMP} environment
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variable, and some use the @code{TMPDIR} environment variable.
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@item
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If the second argument of @code{save-some-buffers}, @var{pred}, is not
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@code{nil}, then the precise value no longer matters. Any
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non-@code{nil} value means the same as @code{t}: offer to save each
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non-file buffer that has a non-@code{nil} value for
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@code{buffer-offer-save}.
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@item
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The variable @code{inhibit-modification-hooks}
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has no special meaning.
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@item
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The hook @code{fontification-functions} has been eliminated,
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but there are other hooks, such as @code{window-scroll-functions},
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that you can use to do a similar job.
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@item
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The variable @code{redisplay-dont-pause}
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has no special meaning.
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@item
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The hook @code{calendar-move-hook} has been deleted.
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@item
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The function @code{move-to-column} treats any non-@code{nil}
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second argument just like @code{t}.
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@end itemize
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@section Old Lisp Features in Emacs 20.3
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Here are the most important of the features that you will learn
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to do without in Emacs 20.3:
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Here are changes in the Lisp language itself:
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@itemize @bullet
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@item
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The functions @code{line-beginning-position} and @code{line-end-position}
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have been eliminated.
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@item
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The functions @code{directory-files-and-attributes},
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@code{file-attributes-lessp}, and @code{file-expand-wildcards}, have
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been eliminated.
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@item
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The functions @code{decode-coding-region} and @code{encode-coding-region}
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leave text properties untouched, in case that is useful. (It rarely makes
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any sense, though.)
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@item
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The functions @code{position-bytes} and @code{byte-to-position} have
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been eliminated.
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@item
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Temporary buffers made with @code{with-output-to-temp-buffer} are now
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modifiable by default, and use Fundamental mode rather than Help mode.
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@item
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The functions @code{sref} interprets its @var{index} argument as a
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number of bytes, not a number of characters. And the function
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@code{char-bytes} actually tries to report on the number of bytes that a
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character occupies.
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@item
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The function @code{process-running-child-p} has been eliminated.
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@item
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The function @code{interrupt-process} and similar functions no longer do
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anything special when the second argument is @code{lambda}.
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@item
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The function @code{define-prefix-command} accepts only two arguments.
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@item
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The meaning of the second argument to @code{read-char},
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@code{read-event}, and @code{read-char-exclusive} has been reversed:
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they use the current input method if the argument is if @code{nil}.
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@item
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The function @code{with-temp-message} has been eliminated.
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@item
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The function @code{clear-this-command-keys} has been eliminated.
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@item
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The functions @code{gap-position} and @code{gap-size} have been eliminated.
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@item
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In @code{modify-face}, an argument of @code{(nil)} has no special
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meaning.
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@item
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The base64 conversion functions have been eliminated.
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@item
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Wildcard support has been eliminated from @code{find-file}
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and allied functions.
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@item
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@code{file-attributes} returns the file size and the file inode number
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only as a simple integer.
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@end itemize
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