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, Calendar, 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.
33 Faces have fewer attributes. The attributes @code{:family},
34 @code{:height}, @code{:width}, @code{:weight}, and @code{:slant},
35 have been replaced with a font name, a ``bold'' flag, and an
38 The attributes @code{:overline}, @code{:strike-through} and @code{:box}
39 have been eliminated too. Underlining now always has the same color as
40 the text---using any other color would be bad taste.
42 With fewer font attributes, there are no functions
43 @code{set-face-attribute} and @code{face-attribute}. Instead, you
44 access these attributes using functions such as @code{face-font}, and
45 set them with functions such as @code{set-face-font}. (These functions
46 were available in Emacs 21, but are not as useful there.)
49 The standard faces @code{scroll-bar}, @code{menu}, @code{border},
50 @code{cursor}, and @code{mouse} have been eliminated. They are rather
51 strange, as faces, and therefore shouldn't really exist. You can use
52 @code{set-border-color}, @code{set-cursor-color} and
53 @code{set-mouse-color} to specify the colors for the frame border, the
54 text cursor, and the mouse cursor. To specify menu colors, use X
58 Emacs will respect your peace and quiet, aside from occasional beeps,
59 because there are no facilities for playing sounds.
62 Regular expressions do not support the POSIX character classes
63 such as @samp{[:alpha:]}. All characters are created equal.
66 Hash tables have been eliminated; use alists instead.
69 The Lisp printer does not detect and report circular structure. That is
70 ok, because the Lisp reader cannot recreate circular structure anyway.
71 However, there is a library @samp{cust-print.el} which can report
75 Emacs provides its own implementation of scroll bars, instead
76 of using those of the X toolkit. They always use the frame foreground
77 and background colors, so you cannot specify different colors for
81 For simplicity, all ASCII characters now have the same height and width.
82 (Certain characters, such as Chinese characters, always have have twice
83 the standard width.) All characters are created equal.
86 The function @code{bitmap-spec-p} has been renamed to
87 @code{pixmap-spec-p} to encourage users to practice Emacs' help system
88 while trying to find it.
91 Tooltips operate using ordinary Emacs frames.
94 Areas of the mode line are not mouse-sensitive; however, some mouse
95 commands are available for the mode line as a whole.
98 Windows cannot have header lines. Conversely, there is no way to turn
99 off the mode line of a window unless it is a minibuffer.
102 Plain dashes are the only separators you can use in a menu.
105 Vertical fractional scrolling does not exist.
108 The functions @code{format} and @code{message} ignore and discard text
112 Colors are supported only on window systems, not on text-only terminals.
113 So the support functions for colors on text-only terminals are
114 not needed, and have been eliminated.
117 The functions @code{color-values}, @code{color-defined-p} and
118 @code{defined-colors} have been renamed to @code{x-color-values},
119 @code{x-color-defined-p} and @code{x-defined-colors}.
122 Windows cannot be made fixed-width or fixed-height;
123 Emacs will adjust the size of all windows when it needs to.
126 The string used as the value of the @code{before-string} or
127 @code{after-string} property must contain only characters that display
128 as a single column---control characters, including tabs and newlines,
129 will give strange results.
132 The minibuffer prompt does not actually appear in content of the
133 minibuffer; it is displayed specially in the minibuffer window.
136 The ``exclusive open'' feature of @code{write-region}
137 has been eliminated; any non-@code{nil} value for the seventh
138 argument now means to ask the user for confirmation.
141 The function @code{buffer-size} always reports on the
145 The function @code{assoc-delete-all} has itself been deleted.
149 The variable @code{small-temporary-file-directory} has no special
150 meaning. There's only one variable for specifying which directory to
151 use for temporary files, @code{temporary-file-directory}, but not all
152 Emacs features use it anyway. Some use the @code{TMP} environment
153 variable, and some use the @code{TMPDIR} environment variable.
156 The variable @code{inhibit-modification-hooks}
157 has no special meaning.
160 The hook @code{fontification-functions} has been eliminated,
161 but there are other hooks, such as @code{window-scroll-functions},
162 that you can use to do a similar job.
165 The variable @code{redisplay-dont-pause}
166 has no special meaning.
169 The hook @code{calendar-move-hook} has been deleted.
172 The function @code{move-to-column} treats any non-@code{nil}
173 second argument just like @code{t}.
176 @section Old Lisp Features in Emacs 20.3
178 Here are the most important of the features that you will learn
179 to do without in Emacs 20.3:
181 Here are changes in the Lisp language itself:
185 The functions @code{line-beginning-position} and @code{line-end-position}
186 have been eliminated.
189 The functions @code{directory-files-and-attributes},
190 @code{file-attributes-lessp}, and @code{file-expand-wildcards}, have
194 The functions @code{decode-coding-region} and @code{encode-coding-region}
195 leave text properties untouched, in case that is useful. (It rarely makes
199 The functions @code{position-bytes} and @code{byte-to-position} have
203 Temporary buffers made with @code{with-output-to-temp-buffer} are now
204 modifiable by default, and use Fundamental mode rather than Help mode.
207 The functions @code{sref} interprets its @var{index} argument as a
208 number of bytes, not a number of characters. And the function
209 @code{char-bytes} actually tries to report on the number of bytes that a
213 The function @code{process-running-child-p} has been eliminated.
216 The function @code{interrupt-process} and similar functions no longer do
217 anything special when the second argument is @code{lambda}.
220 The function @code{define-prefix-command} accepts only two arguments.
223 The meaning of the second argument to @code{read-char},
224 @code{read-event}, and @code{read-char-exclusive} has been reversed:
225 they use the current input method if the argument is if @code{nil}.
228 The function @code{with-temp-message} has been eliminated.
231 The function @code{clear-this-command-keys} has been eliminated.
234 The functions @code{gap-position} and @code{gap-size} have been eliminated.
237 In @code{modify-face}, an argument of @code{(nil)} has no special
241 The base64 conversion functions have been eliminated.
244 Wildcard support has been eliminated from @code{find-file}
245 and allied functions.
248 @code{file-attributes} returns the file size and the file inode number
249 only as a simple integer.