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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, System Interface, 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; buffers are no
  31 longer subdivided into fields.  (The division of information into
  32 fields is always rather arbitrary.)
  33
  34 @item
  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
  38 ``italic'' flag.
  39
  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.
  43
  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.)
  49
  50 @item
  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
  57 resources.
  58
  59 @item
  60 Emacs will respect your peace and quiet, aside from occasional beeps,
  61 because there are no facilities for playing sounds.
  62
  63 @item
  64 Regular expressions do not support the POSIX character classes
  65 such as @samp{[:alpha:]}.  All characters are created equal.
  66
  67 @item
  68 Hash tables have been eliminated; use alists instead.
  69
  70 @item
  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
  74 circular structure.
  75
  76 @item
  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
  80 the scroll bars.
  81
  82 @item
  83 For simplicity, all 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.
  86
  87 @item
  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.
  91
  92 @item
  93 Tooltips operate using ordinary Emacs frames.
  94
  95 @item
  96 Areas of the mode line are not mouse-sensitive; however, some mouse
  97 commands are available for the mode line as a whole.
  98
  99 @item
 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.
 102
 103 @item
 104 Plain dashes are the only separators you can use in a menu.
 105
 106 @item
 107 Vertical fractional scrolling does not exist.
 108
 109 @item
 110 The functions @code{format} and @code{message} ignore and discard text
 111 properties.
 112
 113 @item
 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.
 117
 118 @item
 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}.
 122
 123 @item
 124 Windows cannot be made fixed-width or fixed-height;
 125 Emacs will adjust the size of all windows when it needs to.
 126
 127 @item
 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.
 132
 133 @item
 134 The minibuffer prompt does not actually appear in content of the
 135 minibuffer; it is displayed specially in the minibuffer window.
 136
 137 @item
 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.
 141
 142 @item
 143 The function @code{buffer-size} always reports on the
 144 current buffer.
 145
 146 @item
 147 The function @code{assoc-delete-all} has itself been deleted.
 148 So there!
 149
 150 @item
 151 The keyword @code{:set-after} no longer does anything in
 152 @code{defcustom}.
 153
 154 @item
 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.
 160
 161 @item
 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}.
 167
 168 @item
 169 The variable @code{inhibit-modification-hooks}
 170 has no special meaning.
 171
 172 @item
 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.
 176
 177 @item
 178 The variable  @code{redisplay-dont-pause}
 179 has no special meaning.
 180
 181 @item
 182 The hook @code{calendar-move-hook} has been deleted.
 183
 184 @item
 185 The function @code{move-to-column} treats any non-@code{nil}
 186 second argument just like @code{t}.
 187 @end itemize
 188
 189 @section Old Lisp Features in Emacs 20.3
 190
 191 Here are the most important of the features that you will learn
 192 to do without in Emacs 20.3:
 193
 194 Here are changes in the Lisp language itself:
 195
 196 @itemize @bullet
 197 @item
 198 The functions @code{line-beginning-position} and @code{line-end-position}
 199 have been eliminated.
 200
 201 @item
 202 The functions @code{directory-files-and-attributes},
 203 @code{file-attributes-lessp}, and @code{file-expand-wildcards}, have
 204 been eliminated.
 205
 206 @item
 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
 209 any sense, though.)
 210
 211 @item
 212 The functions @code{position-bytes} and @code{byte-to-position} have
 213 been eliminated.
 214
 215 @item
 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.
 218
 219 @item
 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
 223 character occupies.
 224
 225 @item
 226 The function @code{process-running-child-p} has been eliminated.
 227
 228 @item
 229 The function @code{interrupt-process} and similar functions no longer do
 230 anything special when the second argument is @code{lambda}.
 231
 232 @item
 233 The function @code{define-prefix-command} accepts only two arguments.
 234
 235 @item
 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}.
 239
 240 @item
 241 The function @code{with-temp-message} has been eliminated.
 242
 243 @item
 244 The function @code{clear-this-command-keys} has been eliminated.
 245
 246 @item
 247 The functions @code{gap-position} and @code{gap-size} have been eliminated.
 248
 249 @item
 250 In @code{modify-face}, an argument of @code{(nil)} has no special
 251 meaning.
 252
 253 @item
 254 The base64 conversion functions have been eliminated.
 255
 256 @item
 257 Wildcard support has been eliminated from @code{find-file}
 258 and allied functions.
 259
 260 @item
 261 @code{file-attributes} returns the file size and the file inode number
 262 only as a simple integer.
 263 @end itemize