2 @c This is part of the GNU Emacs Lisp Reference Manual.
3 @c Copyright (C) 1999 Free Software Foundation, Inc.
4 @c See the file elisp.texi for copying conditions.
5 @node Antinews, Tips, System Interface, Top
6 @appendix Emacs 20 Antinews
8 For those users who live backwards in time, here is information about
9 downgrading to Emacs version 20.4. We hope you will enjoy the greater
10 simplicity that results from the absence of many Emacs 21 features. In
11 the following section, we carry this information back to Emacs
12 20.3, for which the previous printed edition of this manual was made.
14 @section Old Lisp Features in Emacs 20
18 The @code{push} and @code{pop} macros are not defined.
21 You can't display images in buffers. (Emacs is meant for editing text.)
22 With no images, there are no display margins, and no tool bars.
25 The @code{display} text property has no special meaning; you can use it
26 freely in Lisp programs, with no effects except what you implement for
27 yourself. With no images, who needs the @code{display} text property?
30 The @code{field} text property has no special meaning; buffers are no
31 longer subdivided into fields. (The division of information into
32 fields is always rather arbitrary.)
35 Faces have fewer attributes. The attributes @code{:family},
36 @code{:height}, @code{:width}, @code{:weight}, and @code{:slant},
37 have been replaced with a font name, a ``bold'' flag, and an
40 The attributes @code{:overline}, @code{:strike-through} and @code{:box}
41 have been eliminated too. Underlining now always has the same color as
42 the text---using any other color would be bad taste.
44 With fewer font attributes, there are no functions
45 @code{set-face-attribute} and @code{face-attribute}. Instead, you
46 access these attributes using functions such as @code{face-font}, and
47 set them with functions such as @code{set-face-font}. (These functions
48 were available in Emacs 21, but are not as useful there.)
51 The standard faces @code{scroll-bar}, @code{menu}, @code{border},
52 @code{cursor}, and @code{mouse} have been eliminated. They are rather
53 strange, as faces, and therefore shouldn't really exist. You can use
54 @code{set-border-color}, @code{set-cursor-color} and
55 @code{set-mouse-color} to specify the colors for the frame border, the
56 text cursor, and the mouse cursor. To specify menu colors, use X
60 Emacs will respect your peace and quiet, aside from occasional beeps,
61 because there are no facilities for playing sounds.
64 Regular expressions do not support the POSIX character classes
65 such as @samp{[:alpha:]}. All characters are created equal.
68 Hash tables have been eliminated; use alists instead.
71 The Lisp printer does not detect and report circular structure. That is
72 ok, because the Lisp reader cannot recreate circular structure anyway.
73 However, there is a library @samp{cust-print.el} which can report
77 Emacs provides its own implementation of scroll bars, instead
78 of using those of the X toolkit. They always use the frame foreground
79 and background colors, so you cannot specify different colors for
83 For simplicity, all @sc{ascii} characters now have the same height and width.
84 (Certain characters, such as Chinese characters, always have twice
85 the standard width.) All characters are created equal.
88 The function @code{bitmap-spec-p} has been renamed to
89 @code{pixmap-spec-p} to encourage users to practice Emacs' help system
90 while trying to find it.
93 Tooltips operate using ordinary Emacs frames.
96 Areas of the mode line are not mouse-sensitive; however, some mouse
97 commands are available for the mode line as a whole.
100 Windows cannot have header lines. Conversely, there is no way to turn
101 off the mode line of a window unless it is a minibuffer.
104 Plain dashes are the only separators you can use in a menu.
107 Vertical fractional scrolling does not exist.
110 The functions @code{format} and @code{message} ignore and discard text
114 Colors are supported only on window systems, not on text-only terminals.
115 So the support functions for colors on text-only terminals are
116 not needed, and have been eliminated.
119 The functions @code{color-values}, @code{color-defined-p} and
120 @code{defined-colors} have been renamed to @code{x-color-values},
121 @code{x-color-defined-p} and @code{x-defined-colors}.
124 Windows cannot be made fixed-width or fixed-height;
125 Emacs will adjust the size of all windows when it needs to.
128 The string used as the value of the @code{before-string} or
129 @code{after-string} property must contain only characters that display
130 as a single column---control characters, including tabs and newlines,
131 will give strange results.
134 The minibuffer prompt does not actually appear in content of the
135 minibuffer; it is displayed specially in the minibuffer window.
138 The ``exclusive open'' feature of @code{write-region}
139 has been eliminated; any non-@code{nil} value for the seventh
140 argument now means to ask the user for confirmation.
143 The function @code{buffer-size} always reports on the
147 The function @code{assoc-delete-all} has itself been deleted.
151 The keyword @code{:set-after} no longer does anything in
155 The variable @code{small-temporary-file-directory} has no special
156 meaning. There's only one variable for specifying which directory to
157 use for temporary files, @code{temporary-file-directory}, but not all
158 Emacs features use it anyway. Some use the @code{TMP} environment
159 variable, and some use the @code{TMPDIR} environment variable.
162 If the second argument of @code{save-some-buffers}, @var{pred}, is not
163 @code{nil}, then the precise value no longer matters. Any
164 non-@code{nil} value means the same as @code{t}: offer to save each
165 non-file buffer that has a non-@code{nil} value for
166 @code{buffer-offer-save}.
169 The variable @code{inhibit-modification-hooks}
170 has no special meaning.
173 The hook @code{fontification-functions} has been eliminated,
174 but there are other hooks, such as @code{window-scroll-functions},
175 that you can use to do a similar job.
178 The variable @code{redisplay-dont-pause}
179 has no special meaning.
182 The hook @code{calendar-move-hook} has been deleted.
185 The function @code{move-to-column} treats any non-@code{nil}
186 second argument just like @code{t}.
189 @section Old Lisp Features in Emacs 20.3
191 Here are the most important of the features that you will learn
192 to do without in Emacs 20.3:
194 Here are changes in the Lisp language itself:
198 The functions @code{line-beginning-position} and @code{line-end-position}
199 have been eliminated.
202 The functions @code{directory-files-and-attributes},
203 @code{file-attributes-lessp}, and @code{file-expand-wildcards}, have
207 The functions @code{decode-coding-region} and @code{encode-coding-region}
208 leave text properties untouched, in case that is useful. (It rarely makes
212 The functions @code{position-bytes} and @code{byte-to-position} have
216 Temporary buffers made with @code{with-output-to-temp-buffer} are now
217 modifiable by default, and use Fundamental mode rather than Help mode.
220 The functions @code{sref} interprets its @var{index} argument as a
221 number of bytes, not a number of characters. And the function
222 @code{char-bytes} actually tries to report on the number of bytes that a
226 The function @code{process-running-child-p} has been eliminated.
229 The function @code{interrupt-process} and similar functions no longer do
230 anything special when the second argument is @code{lambda}.
233 The function @code{define-prefix-command} accepts only two arguments.
236 The meaning of the second argument to @code{read-char},
237 @code{read-event}, and @code{read-char-exclusive} has been reversed:
238 they use the current input method if the argument is if @code{nil}.
241 The function @code{with-temp-message} has been eliminated.
244 The function @code{clear-this-command-keys} has been eliminated.
247 The functions @code{gap-position} and @code{gap-size} have been eliminated.
250 In @code{modify-face}, an argument of @code{(nil)} has no special
254 The base64 conversion functions have been eliminated.
257 Wildcard support has been eliminated from @code{find-file}
258 and allied functions.
261 @code{file-attributes} returns the file size and the file inode number
262 only as a simple integer.