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   1 @c -*-texinfo-*-
   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
   7
   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.
  13
  14 @section Old Lisp Features in Emacs 20
  15
  16 @itemize @bullet
  17 @item
  18 The @code{push} and @code{pop} macros are not defined.
  19
  20 @item
  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.
  23
  24 @item
  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?
  28
  29 @item
  30 The @code{field} text property has no special meaning.
  31
  32 @item
  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
  36 ``italic'' flag.
  37
  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.
  41
  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.)
  47
  48 @item
  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
  55 resources.
  56
  57 @item
  58 Emacs will respect your peace and quiet, aside from occasional beeps,
  59 because there are no facilities for playing sounds.
  60
  61 @item
  62 Regular expressions do not support the POSIX character classes
  63 such as @samp{[:alpha:]}.  All characters are created equal.
  64
  65 @item
  66 Hash tables have been eliminated; use alists instead.
  67
  68 @item
  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
  72 circular structure.
  73
  74 @item
  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
  78 the scroll bars.
  79
  80 @item
  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.
  84
  85 @item
  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.
  89
  90 @item
  91 Tooltips operate using ordinary Emacs frames.
  92
  93 @item
  94 Areas of the mode line are not mouse-sensitive; however, some mouse
  95 commands are available for the mode line as a whole.
  96
  97 @item
  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.
 100
 101 @item
 102 Plain dashes are the only separators you can use in a menu.
 103
 104 @item
 105 Vertical fractional scrolling does not exist.
 106
 107 @item
 108 The functions @code{format} and @code{message} ignore and discard text
 109 properties.
 110
 111 @item
 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.
 115
 116 @item
 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}.
 120
 121 @item
 122 Windows cannot be made fixed-width or fixed-height;
 123 Emacs will adjust the size of all windows when it needs to.
 124
 125 @item
 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.
 130
 131 @item
 132 The minibuffer prompt does not actually appear in content of the
 133 minibuffer; it is displayed specially in the minibuffer window.
 134
 135 @item
 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.
 139
 140 @item
 141 The function @code{buffer-size} always reports on the
 142 current buffer.
 143
 144 @item
 145 The function @code{assoc-delete-all} has itself been deleted.
 146 So there!
 147
 148 @item
 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.
 154
 155 @item
 156 The variable  @code{inhibit-modification-hooks}
 157 has no special meaning.
 158
 159 @item
 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.
 163
 164 @item
 165 The variable  @code{redisplay-dont-pause}
 166 has no special meaning.
 167
 168 @item
 169 The hook @code{calendar-move-hook} has been deleted.
 170
 171 @item
 172 The function @code{move-to-column} treats any non-@code{nil}
 173 second argument just like @code{t}.
 174 @end itemize
 175
 176 @section Old Lisp Features in Emacs 20.3
 177
 178 Here are the most important of the features that you will learn
 179 to do without in Emacs 20.3:
 180
 181 Here are changes in the Lisp language itself:
 182
 183 @itemize @bullet
 184 @item
 185 The functions @code{line-beginning-position} and @code{line-end-position}
 186 have been eliminated.
 187
 188 @item
 189 The functions @code{directory-files-and-attributes},
 190 @code{file-attributes-lessp}, and @code{file-expand-wildcards}, have
 191 been eliminated.
 192
 193 @item
 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
 196 any sense, though.)
 197
 198 @item
 199 The functions @code{position-bytes} and @code{byte-to-position} have
 200 been eliminated.
 201
 202 @item
 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.
 205
 206 @item
 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
 210 character occupies.
 211
 212 @item
 213 The function @code{process-running-child-p} has been eliminated.
 214
 215 @item
 216 The function @code{interrupt-process} and similar functions no longer do
 217 anything special when the second argument is @code{lambda}.
 218
 219 @item
 220 The function @code{define-prefix-command} accepts only two arguments.
 221
 222 @item
 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}.
 226
 227 @item
 228 The function @code{with-temp-message} has been eliminated.
 229
 230 @item
 231 The function @code{clear-this-command-keys} has been eliminated.
 232
 233 @item
 234 The functions @code{gap-position} and @code{gap-size} have been eliminated.
 235
 236 @item
 237 In @code{modify-face}, an argument of @code{(nil)} has no special
 238 meaning.
 239
 240 @item
 241 The base64 conversion functions have been eliminated.
 242
 243 @item
 244 Wildcard support has been eliminated from @code{find-file}
 245 and allied functions.
 246
 247 @item
 248 @code{file-attributes} returns the file size and the file inode number
 249 only as a simple integer.
 250 @end itemize