Mercurial > hg > xemacs-beta
annotate man/lispref/help.texi @ 5044:e84a30b0e4a2
remove duplicative code in change_frame_size()
-------------------- ChangeLog entries follow: --------------------
src/ChangeLog addition:
2010-02-15 Ben Wing <ben@xemacs.org>
* frame.c (change_frame_size_1):
Simplify the logic in this function.
(1) Don't allow 0 as the value of height or width. The old code
that tried to allow this was totally broken, anyway, so obviously
this never happens any more.
(2) Don't duplicate the code in frame_conversion_internal() that
converts displayable pixel size to total pixel size -- just call
that function.
| author | Ben Wing <ben@xemacs.org> |
|---|---|
| date | Mon, 15 Feb 2010 22:58:10 -0600 |
| parents | 755ae5b97edb |
| children | 9fae6227ede5 |
| rev | line source |
|---|---|
| 428 | 1 @c -*-texinfo-*- |
| 2 @c This is part of the XEmacs Lisp Reference Manual. | |
| 3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc. | |
| 4 @c See the file lispref.texi for copying conditions. | |
| 5 @setfilename ../../info/help.info | |
| 6 @node Documentation, Files, Modes, Top | |
| 7 @chapter Documentation | |
| 8 @cindex documentation strings | |
| 9 | |
| 10 XEmacs Lisp has convenient on-line help facilities, most of which | |
| 11 derive their information from the documentation strings associated with | |
| 12 functions and variables. This chapter describes how to write good | |
| 13 documentation strings for your Lisp programs, as well as how to write | |
| 14 programs to access documentation. | |
| 15 | |
| 16 Note that the documentation strings for XEmacs are not the same thing | |
| 17 as the XEmacs manual. Manuals have their own source files, written in | |
| 18 the Texinfo language; documentation strings are specified in the | |
| 19 definitions of the functions and variables they apply to. A collection | |
| 20 of documentation strings is not sufficient as a manual because a good | |
| 21 manual is not organized in that fashion; it is organized in terms of | |
| 22 topics of discussion. | |
| 23 | |
| 24 @menu | |
| 25 * Documentation Basics:: Good style for doc strings. | |
| 26 Where to put them. How XEmacs stores them. | |
| 27 * Accessing Documentation:: How Lisp programs can access doc strings. | |
| 28 * Keys in Documentation:: Substituting current key bindings. | |
| 29 * Describing Characters:: Making printable descriptions of | |
| 30 non-printing characters and key sequences. | |
| 31 * Help Functions:: Subroutines used by XEmacs help facilities. | |
| 32 * Obsoleteness:: Upgrading Lisp functionality over time. | |
| 33 @end menu | |
| 34 | |
| 35 @node Documentation Basics | |
| 36 @section Documentation Basics | |
| 37 @cindex documentation conventions | |
| 38 @cindex writing a documentation string | |
| 39 @cindex string, writing a doc string | |
| 40 | |
| 41 A documentation string is written using the Lisp syntax for strings, | |
| 42 with double-quote characters surrounding the text of the string. This | |
| 43 is because it really is a Lisp string object. The string serves as | |
| 44 documentation when it is written in the proper place in the definition | |
| 45 of a function or variable. In a function definition, the documentation | |
| 46 string follows the argument list. In a variable definition, the | |
| 47 documentation string follows the initial value of the variable. | |
| 48 | |
| 49 When you write a documentation string, make the first line a complete | |
| 50 sentence (or two complete sentences) since some commands, such as | |
| 51 @code{apropos}, show only the first line of a multi-line documentation | |
| 52 string. Also, you should not indent the second line of a documentation | |
| 53 string, if you have one, because that looks odd when you use @kbd{C-h f} | |
| 54 (@code{describe-function}) or @kbd{C-h v} (@code{describe-variable}). | |
| 55 @xref{Documentation Tips}. | |
| 56 | |
| 57 Documentation strings may contain several special substrings, which | |
| 58 stand for key bindings to be looked up in the current keymaps when the | |
| 59 documentation is displayed. This allows documentation strings to refer | |
| 60 to the keys for related commands and be accurate even when a user | |
| 61 rearranges the key bindings. (@xref{Accessing Documentation}.) | |
| 62 | |
| 63 Within the Lisp world, a documentation string is accessible through | |
| 64 the function or variable that it describes: | |
| 65 | |
| 66 @itemize @bullet | |
| 67 @item | |
| 68 The documentation for a function is stored in the function definition | |
| 69 itself (@pxref{Lambda Expressions}). The function | |
| 70 @code{documentation} knows how to extract it. | |
| 71 | |
| 72 @item | |
| 73 @kindex variable-documentation | |
| 74 The documentation for a variable is stored in the variable's property | |
| 75 list under the property name @code{variable-documentation}. The | |
| 76 function @code{documentation-property} knows how to extract it. | |
| 77 @end itemize | |
| 78 | |
| 79 @cindex @file{DOC} (documentation) file | |
| 80 To save space, the documentation for preloaded functions and variables | |
| 81 (including primitive functions and autoloaded functions) is stored in | |
| 82 the @dfn{internal doc file} @file{DOC}. The documentation for functions | |
| 83 and variables loaded during the XEmacs session from byte-compiled files | |
| 84 is stored in those very same byte-compiled files (@pxref{Docs and | |
| 85 Compilation}). | |
| 86 | |
| 87 XEmacs does not keep documentation strings in memory unless necessary. | |
| 88 Instead, XEmacs maintains, for preloaded symbols, an integer offset into | |
| 89 the internal doc file, and for symbols loaded from byte-compiled files, | |
| 90 a list containing the filename of the byte-compiled file and an integer | |
| 91 offset, in place of the documentation string. The functions | |
| 92 @code{documentation} and @code{documentation-property} use that | |
| 93 information to read the documentation from the appropriate file; this is | |
| 94 transparent to the user. | |
| 95 | |
| 96 For information on the uses of documentation strings, see @ref{Help, , | |
| 446 | 97 Help, xemacs, The XEmacs Reference Manual}. |
| 428 | 98 |
| 99 @c Wordy to prevent overfull hbox. --rjc 15mar92 | |
| 100 The @file{emacs/lib-src} directory contains two utilities that you can | |
| 101 use to print nice-looking hardcopy for the file | |
| 102 @file{emacs/etc/DOC-@var{version}}. These are @file{sorted-doc.c} and | |
| 103 @file{digest-doc.c}. | |
| 104 | |
| 105 @node Accessing Documentation | |
| 106 @section Access to Documentation Strings | |
| 107 | |
| 108 @defun documentation-property symbol property &optional verbatim | |
| 109 This function returns the documentation string that is recorded in | |
| 110 @var{symbol}'s property list under property @var{property}. It | |
| 111 retrieves the text from a file if necessary, and runs | |
| 112 @code{substitute-command-keys} to substitute actual key bindings. (This | |
| 113 substitution is not done if @var{verbatim} is non-@code{nil}; the | |
| 114 @var{verbatim} argument exists only as of Emacs 19.) | |
| 115 | |
| 116 @smallexample | |
| 117 @group | |
| 118 (documentation-property 'command-line-processed | |
| 119 'variable-documentation) | |
| 120 @result{} "t once command line has been processed" | |
| 121 @end group | |
| 122 @group | |
| 123 (symbol-plist 'command-line-processed) | |
| 124 @result{} (variable-documentation 188902) | |
| 125 @end group | |
| 126 @end smallexample | |
| 127 @end defun | |
| 128 | |
| 129 @defun documentation function &optional verbatim | |
| 130 This function returns the documentation string of @var{function}. It | |
| 131 reads the text from a file if necessary. Then (unless @var{verbatim} is | |
| 132 non-@code{nil}) it calls @code{substitute-command-keys}, to return a | |
| 133 value containing the actual (current) key bindings. | |
| 134 | |
| 135 The function @code{documentation} signals a @code{void-function} error | |
| 136 if @var{function} has no function definition. However, it is ok if | |
| 137 the function definition has no documentation string. In that case, | |
| 138 @code{documentation} returns @code{nil}. | |
| 139 @end defun | |
| 140 | |
| 141 @c Wordy to prevent overfull hboxes. --rjc 15mar92 | |
| 142 Here is an example of using the two functions, @code{documentation} and | |
| 143 @code{documentation-property}, to display the documentation strings for | |
| 144 several symbols in a @samp{*Help*} buffer. | |
| 145 | |
| 146 @smallexample | |
| 147 @group | |
| 148 (defun describe-symbols (pattern) | |
| 149 "Describe the XEmacs Lisp symbols matching PATTERN. | |
| 150 All symbols that have PATTERN in their name are described | |
| 151 in the `*Help*' buffer." | |
| 152 (interactive "sDescribe symbols matching: ") | |
| 153 (let ((describe-func | |
| 154 (function | |
| 155 (lambda (s) | |
| 156 @end group | |
| 157 @group | |
| 158 ;; @r{Print description of symbol.} | |
| 159 (if (fboundp s) ; @r{It is a function.} | |
| 160 (princ | |
| 161 (format "%s\t%s\n%s\n\n" s | |
| 162 (if (commandp s) | |
| 163 (let ((keys (where-is-internal s))) | |
| 164 (if keys | |
| 165 (concat | |
| 166 "Keys: " | |
| 167 (mapconcat 'key-description | |
| 168 keys " ")) | |
| 169 "Keys: none")) | |
| 170 "Function") | |
| 171 @end group | |
| 172 @group | |
| 173 (or (documentation s) | |
| 174 "not documented")))) | |
| 175 | |
| 176 (if (boundp s) ; @r{It is a variable.} | |
| 177 @end group | |
| 178 @group | |
| 179 (princ | |
| 180 (format "%s\t%s\n%s\n\n" s | |
| 181 (if (user-variable-p s) | |
| 182 "Option " "Variable") | |
| 183 @end group | |
| 184 @group | |
| 185 (or (documentation-property | |
| 186 s 'variable-documentation) | |
| 187 "not documented"))))))) | |
| 188 sym-list) | |
| 189 @end group | |
| 190 | |
| 191 @group | |
| 192 ;; @r{Build a list of symbols that match pattern.} | |
| 193 (mapatoms (function | |
| 194 (lambda (sym) | |
| 195 (if (string-match pattern (symbol-name sym)) | |
| 196 (setq sym-list (cons sym sym-list)))))) | |
| 197 @end group | |
| 198 | |
| 199 @group | |
| 200 ;; @r{Display the data.} | |
| 201 (with-output-to-temp-buffer "*Help*" | |
| 202 (mapcar describe-func (sort sym-list 'string<)) | |
| 203 (print-help-return-message)))) | |
| 204 @end group | |
| 205 @end smallexample | |
| 206 | |
| 207 The @code{describe-symbols} function works like @code{apropos}, | |
| 208 but provides more information. | |
| 209 | |
| 210 @smallexample | |
| 211 @group | |
| 212 (describe-symbols "goal") | |
| 213 | |
| 214 ---------- Buffer: *Help* ---------- | |
| 215 goal-column Option | |
| 216 *Semipermanent goal column for vertical motion, as set by C-x C-n, or nil. | |
| 217 @end group | |
| 218 @c Do not blithely break or fill these lines. | |
| 219 @c That makes them incorrect. | |
| 220 | |
| 221 @group | |
| 222 set-goal-column Command: C-x C-n | |
| 223 Set the current horizontal position as a goal for C-n and C-p. | |
| 224 @end group | |
| 225 @c DO NOT put a blank line here! That is factually inaccurate! | |
| 226 @group | |
| 227 Those commands will move to this position in the line moved to | |
| 228 rather than trying to keep the same horizontal position. | |
| 444 | 229 With a non-@code{nil} argument, clears out the goal column |
| 428 | 230 so that C-n and C-p resume vertical motion. |
| 231 The goal column is stored in the variable `goal-column'. | |
| 232 @end group | |
| 233 | |
| 234 @group | |
| 235 temporary-goal-column Variable | |
| 236 Current goal column for vertical motion. | |
| 237 It is the column where point was | |
| 238 at the start of current run of vertical motion commands. | |
| 239 When the `track-eol' feature is doing its job, the value is 9999. | |
| 240 ---------- Buffer: *Help* ---------- | |
| 241 @end group | |
| 242 @end smallexample | |
| 243 | |
| 244 @defun Snarf-documentation filename | |
| 245 This function is used only during XEmacs initialization, just before | |
| 246 the runnable XEmacs is dumped. It finds the file offsets of the | |
| 247 documentation strings stored in the file @var{filename}, and records | |
| 248 them in the in-core function definitions and variable property lists in | |
| 249 place of the actual strings. @xref{Building XEmacs}. | |
| 250 | |
| 251 XEmacs finds the file @var{filename} in the @file{lib-src} directory. | |
| 252 When the dumped XEmacs is later executed, the same file is found in the | |
| 253 directory @code{doc-directory}. The usual value for @var{filename} is | |
| 254 @file{DOC}, but this can be changed by modifying the variable | |
| 255 @code{internal-doc-file-name}. | |
| 256 @end defun | |
| 257 | |
| 258 @defvar internal-doc-file-name | |
| 259 This variable holds the name of the file containing documentation | |
| 260 strings of built-in symbols, usually @file{DOC}. The full pathname of | |
| 261 the internal doc file is @samp{(concat doc-directory internal-doc-file-name)}. | |
| 262 @end defvar | |
| 263 | |
| 264 @defvar doc-directory | |
| 265 This variable holds the name of the directory which contains the | |
| 266 @dfn{internal doc file} that contains documentation strings for built-in | |
| 267 and preloaded functions and variables. | |
| 268 | |
| 269 In most cases, this is the same as @code{exec-directory}. They may be | |
| 270 different when you run XEmacs from the directory where you built it, | |
| 271 without actually installing it. See @code{exec-directory} in @ref{Help | |
| 272 Functions}. | |
| 273 | |
| 274 In older Emacs versions, @code{exec-directory} was used for this. | |
| 275 @end defvar | |
| 276 | |
| 277 @defvar data-directory | |
| 278 This variable holds the name of the directory in which XEmacs finds | |
| 279 certain system independent documentation and text files that come | |
| 280 with XEmacs. In older Emacs versions, @code{exec-directory} was used for | |
| 281 this. | |
| 282 @end defvar | |
| 283 | |
| 284 @node Keys in Documentation | |
| 285 @section Substituting Key Bindings in Documentation | |
| 286 @cindex documentation, keys in | |
| 287 @cindex keys in documentation strings | |
| 288 @cindex substituting keys in documentation | |
| 289 | |
| 290 When documentation strings refer to key sequences, they should use the | |
| 291 current, actual key bindings. They can do so using certain special text | |
| 292 sequences described below. Accessing documentation strings in the usual | |
| 293 way substitutes current key binding information for these special | |
| 294 sequences. This works by calling @code{substitute-command-keys}. You | |
| 295 can also call that function yourself. | |
| 296 | |
| 297 Here is a list of the special sequences and what they mean: | |
| 298 | |
| 299 @table @code | |
| 300 @item \[@var{command}] | |
| 301 stands for a key sequence that will invoke @var{command}, or @samp{M-x | |
| 302 @var{command}} if @var{command} has no key bindings. | |
| 303 | |
| 304 @item \@{@var{mapvar}@} | |
| 305 stands for a summary of the value of @var{mapvar}, which should be a | |
| 306 keymap. The summary is made by @code{describe-bindings}. | |
| 307 | |
| 308 @item \<@var{mapvar}> | |
| 309 stands for no text itself. It is used for a side effect: it specifies | |
| 310 @var{mapvar} as the keymap for any following @samp{\[@var{command}]} | |
| 311 sequences in this documentation string. | |
| 312 | |
| 313 @item \= | |
| 314 quotes the following character and is discarded; this @samp{\=\=} puts | |
| 315 @samp{\=} into the output, and @samp{\=\[} puts @samp{\[} into the output. | |
| 316 @end table | |
| 317 | |
| 318 @strong{Please note:} Each @samp{\} must be doubled when written in a | |
| 319 string in XEmacs Lisp. | |
| 320 | |
| 321 @defun substitute-command-keys string | |
| 322 This function scans @var{string} for the above special sequences and | |
| 323 replaces them by what they stand for, returning the result as a string. | |
| 324 This permits display of documentation that refers accurately to the | |
| 325 user's own customized key bindings. | |
| 326 @end defun | |
| 327 | |
| 328 Here are examples of the special sequences: | |
| 329 | |
| 330 @smallexample | |
| 331 @group | |
| 332 (substitute-command-keys | |
| 333 "To abort recursive edit, type: \\[abort-recursive-edit]") | |
| 334 @result{} "To abort recursive edit, type: C-]" | |
| 335 @end group | |
| 336 | |
| 337 @group | |
| 338 (substitute-command-keys | |
| 339 "The keys that are defined for the minibuffer here are: | |
| 340 \\@{minibuffer-local-must-match-map@}") | |
| 341 @result{} "The keys that are defined for the minibuffer here are: | |
| 342 @end group | |
| 343 | |
| 344 ? minibuffer-completion-help | |
| 345 SPC minibuffer-complete-word | |
| 346 TAB minibuffer-complete | |
| 347 LFD minibuffer-complete-and-exit | |
| 348 RET minibuffer-complete-and-exit | |
| 349 C-g abort-recursive-edit | |
| 350 " | |
| 351 | |
| 352 @group | |
| 353 (substitute-command-keys | |
| 354 "To abort a recursive edit from the minibuffer, type\ | |
| 355 \\<minibuffer-local-must-match-map>\\[abort-recursive-edit].") | |
| 356 @result{} "To abort a recursive edit from the minibuffer, type C-g." | |
| 357 @end group | |
| 358 | |
| 359 @group | |
| 360 (substitute-command-keys | |
| 361 "Substrings of the form \\=\\@{MAPVAR@} are replaced by summaries | |
| 444 | 362 \(made by `describe-bindings') of the value of MAPVAR, taken as a keymap. |
| 428 | 363 Substrings of the form \\=\\<MAPVAR> specify to use the value of MAPVAR |
| 364 as the keymap for future \\=\\[COMMAND] substrings. | |
| 365 \\=\\= quotes the following character and is discarded; | |
| 366 thus, \\=\\=\\=\\= puts \\=\\= into the output, | |
| 367 and \\=\\=\\=\\[ puts \\=\\[ into the output.") | |
| 368 @result{} "Substrings of the form \@{MAPVAR@} are replaced by summaries | |
| 444 | 369 (made by `describe-bindings') of the value of MAPVAR, taken as a keymap. |
| 428 | 370 Substrings of the form \<MAPVAR> specify to use the value of MAPVAR |
| 371 as the keymap for future \[COMMAND] substrings. | |
| 372 \= quotes the following character and is discarded; | |
| 373 thus, \=\= puts \= into the output, | |
| 374 and \=\[ puts \[ into the output." | |
| 375 @end group | |
| 376 @end smallexample | |
| 377 | |
| 378 @node Describing Characters | |
| 379 @section Describing Characters for Help Messages | |
| 380 | |
| 381 These functions convert events, key sequences or characters to textual | |
| 382 descriptions. These descriptions are useful for including arbitrary | |
| 383 text characters or key sequences in messages, because they convert | |
| 384 non-printing and whitespace characters to sequences of printing | |
| 385 characters. The description of a non-whitespace printing character is | |
| 386 the character itself. | |
| 387 | |
| 388 @defun key-description sequence | |
| 389 @cindex XEmacs event standard notation | |
| 390 This function returns a string containing the XEmacs standard notation | |
| 391 for the input events in @var{sequence}. The argument @var{sequence} may | |
| 392 be a string, vector or list. @xref{Events}, for more information about | |
| 393 valid events. See also the examples for @code{single-key-description}, | |
| 394 below. | |
| 395 @end defun | |
| 396 | |
| 397 @defun single-key-description key | |
| 398 @cindex event printing | |
| 399 @cindex character printing | |
| 400 @cindex control character printing | |
| 401 @cindex meta character printing | |
| 402 This function returns a string describing @var{key} in the standard | |
| 403 XEmacs notation for keyboard input. A normal printing character appears | |
| 404 as itself, but a control character turns into a string starting with | |
| 405 @samp{C-}, a meta character turns into a string starting with @samp{M-}, | |
| 406 and space, linefeed, etc.@: appear as @samp{SPC}, @samp{LFD}, etc. A | |
| 407 symbol appears as the name of the symbol. An event that is a list | |
| 408 appears as the name of the symbol in the @sc{car} of the list. | |
| 409 | |
| 410 @smallexample | |
| 411 @group | |
| 412 (single-key-description ?\C-x) | |
| 413 @result{} "C-x" | |
| 414 @end group | |
| 415 @group | |
| 416 (key-description "\C-x \M-y \n \t \r \f123") | |
| 417 @result{} "C-x SPC M-y SPC LFD SPC TAB SPC RET SPC C-l 1 2 3" | |
| 418 @end group | |
| 419 @group | |
| 462 | 420 (single-key-description 'kp-next) |
| 421 @result{} "kp-next" | |
| 428 | 422 @end group |
| 423 @group | |
| 424 (single-key-description '(shift button1)) | |
| 425 @result{} "Sh-button1" | |
| 426 @end group | |
| 427 @end smallexample | |
| 428 @end defun | |
| 429 | |
| 430 @defun text-char-description character | |
| 431 This function returns a string describing @var{character} in the | |
| 432 standard XEmacs notation for characters that appear in text---like | |
| 433 @code{single-key-description}, except that control characters are | |
| 434 represented with a leading caret (which is how control characters in | |
| 435 XEmacs buffers are usually displayed). | |
| 436 | |
| 437 @smallexample | |
| 438 @group | |
| 439 (text-char-description ?\C-c) | |
| 440 @result{} "^C" | |
| 441 @end group | |
| 442 @group | |
| 443 (text-char-description ?\M-m) | |
| 444 @result{} "M-m" | |
| 445 @end group | |
| 446 @group | |
| 447 (text-char-description ?\C-\M-m) | |
| 448 @result{} "M-^M" | |
| 449 @end group | |
| 450 @end smallexample | |
| 451 @end defun | |
| 452 | |
| 453 @node Help Functions | |
| 454 @section Help Functions | |
| 455 | |
| 456 XEmacs provides a variety of on-line help functions, all accessible to | |
| 457 the user as subcommands of the prefix @kbd{C-h}, or on some keyboards, | |
| 458 @kbd{help}. For more information about them, see @ref{Help, , Help, | |
| 446 | 459 emacs, The XEmacs Lisp Reference Manual}. Here we describe some |
| 428 | 460 program-level interfaces to the same information. |
| 461 | |
| 462 @deffn Command apropos regexp &optional do-all predicate | |
| 463 This function finds all symbols whose names contain a match for the | |
| 464 regular expression @var{regexp}, and returns a list of them | |
| 465 (@pxref{Regular Expressions}). It also displays the symbols in a buffer | |
| 466 named @samp{*Help*}, each with a one-line description. | |
| 467 | |
| 468 @c Emacs 19 feature | |
| 469 If @var{do-all} is non-@code{nil}, then @code{apropos} also shows | |
| 470 key bindings for the functions that are found. | |
| 471 | |
| 472 If @var{predicate} is non-@code{nil}, it should be a function to be | |
| 473 called on each symbol that has matched @var{regexp}. Only symbols for | |
| 474 which @var{predicate} returns a non-@code{nil} value are listed or | |
| 475 displayed. | |
| 476 | |
| 477 In the first of the following examples, @code{apropos} finds all the | |
| 478 symbols with names containing @samp{exec}. In the second example, it | |
| 479 finds and returns only those symbols that are also commands. | |
| 480 (We don't show the output that results in the @samp{*Help*} buffer.) | |
| 481 | |
| 482 @smallexample | |
| 483 @group | |
| 484 (apropos "exec") | |
| 485 @result{} (Buffer-menu-execute command-execute exec-directory | |
| 486 exec-path execute-extended-command execute-kbd-macro | |
| 487 executing-kbd-macro executing-macro) | |
| 488 @end group | |
| 489 | |
| 490 @group | |
| 491 (apropos "exec" nil 'commandp) | |
| 492 @result{} (Buffer-menu-execute execute-extended-command) | |
| 493 @end group | |
| 494 @ignore | |
| 495 @group | |
| 496 ---------- Buffer: *Help* ---------- | |
| 497 Buffer-menu-execute | |
| 498 Function: Save and/or delete buffers marked with | |
| 499 M-x Buffer-menu-save or M-x Buffer-menu-delete commands. | |
| 500 execute-extended-command ESC x | |
| 501 Function: Read function name, then read its | |
| 502 arguments and call it. | |
| 503 ---------- Buffer: *Help* ---------- | |
| 504 @end group | |
| 505 @end ignore | |
| 506 @end smallexample | |
| 507 | |
| 508 @code{apropos} is used by various user-level commands, such as @kbd{C-h | |
| 509 a} (@code{hyper-apropos}), a graphical front-end to @code{apropos}; and | |
| 510 @kbd{C-h A} (@code{command-apropos}), which does an apropos over only | |
| 511 those functions which are user commands. @code{command-apropos} calls | |
| 512 @code{apropos}, specifying a @var{predicate} to restrict the output to | |
| 513 symbols that are commands. The call to @code{apropos} looks like this: | |
| 514 | |
| 515 @smallexample | |
| 516 (apropos string t 'commandp) | |
| 517 @end smallexample | |
| 518 @end deffn | |
| 519 | |
| 520 @c Emacs 19 feature | |
| 521 @c super-apropos is obsolete - function absorbed by apropos --mrb | |
| 522 @ignore | |
| 523 @deffn Command super-apropos regexp &optional do-all | |
| 524 This function differs from @code{apropos} in that it searches | |
| 525 documentation strings as well as symbol names for matches for | |
| 526 @var{regexp}. By default, it searches the documentation strings only | |
| 527 for preloaded functions and variables. If @var{do-all} is | |
| 528 non-@code{nil}, it scans the names and documentation strings of all | |
| 529 functions and variables. | |
| 530 @end deffn | |
| 531 @end ignore | |
| 532 | |
| 533 @defvar help-map | |
| 534 The value of this variable is a local keymap for characters following the | |
| 535 Help key, @kbd{C-h}. | |
| 536 @end defvar | |
| 537 | |
| 538 @deffn {Prefix Command} help-command | |
| 539 This symbol is not a function; its function definition is actually the | |
| 540 keymap known as @code{help-map}. It is defined in @file{help.el} as | |
| 541 follows: | |
| 542 | |
| 543 @smallexample | |
| 544 @group | |
| 545 (define-key global-map "\C-h" 'help-command) | |
| 546 (fset 'help-command help-map) | |
| 547 @end group | |
| 548 @end smallexample | |
| 549 @end deffn | |
| 550 | |
| 551 @defun print-help-return-message &optional function | |
| 552 This function builds a string that explains how to restore the previous | |
| 553 state of the windows after a help command. After building the message, | |
| 554 it applies @var{function} to it if @var{function} is non-@code{nil}. | |
| 555 Otherwise it calls @code{message} to display it in the echo area. | |
| 556 | |
| 557 This function expects to be called inside a | |
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4905
755ae5b97edb
Change "special form" to "special operator" in our sources.
Aidan Kehoe <kehoea@parhasard.net>
parents:
2444
diff
changeset
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558 @code{with-output-to-temp-buffer} form, and expects |
|
755ae5b97edb
Change "special form" to "special operator" in our sources.
Aidan Kehoe <kehoea@parhasard.net>
parents:
2444
diff
changeset
|
559 @code{standard-output} to have the value bound by that special operator. |
| 428 | 560 For an example of its use, see the long example in @ref{Accessing |
| 561 Documentation}. | |
| 562 @end defun | |
| 563 | |
| 564 @defvar help-char | |
| 565 The value of this variable is the help character---the character that | |
| 566 XEmacs recognizes as meaning Help. By default, it is the character | |
| 567 @samp{?\^H} (ASCII 8), which is @kbd{C-h}. When XEmacs reads this | |
| 568 character, if @code{help-form} is non-@code{nil} Lisp expression, it | |
| 569 evaluates that expression, and displays the result in a window if it is | |
| 570 a string. | |
| 571 | |
| 572 @code{help-char} can be a character or a key description such as | |
| 573 @code{help} or @code{(meta h)}. | |
| 574 | |
| 575 Usually the value of @code{help-form}'s value is @code{nil}. Then the | |
| 576 help character has no special meaning at the level of command input, and | |
| 577 it becomes part of a key sequence in the normal way. The standard key | |
| 578 binding of @kbd{C-h} is a prefix key for several general-purpose help | |
| 579 features. | |
| 580 | |
| 581 The help character is special after prefix keys, too. If it has no | |
| 582 binding as a subcommand of the prefix key, it runs | |
| 583 @code{describe-prefix-bindings}, which displays a list of all the | |
| 584 subcommands of the prefix key. | |
| 585 @end defvar | |
| 586 | |
| 587 @defvar help-form | |
| 588 If this variable is non-@code{nil}, its value is a form to evaluate | |
| 589 whenever the character @code{help-char} is read. If evaluating the form | |
| 590 produces a string, that string is displayed. | |
| 591 | |
| 592 A command that calls @code{next-command-event} or @code{next-event} | |
| 593 probably should bind @code{help-form} to a non-@code{nil} expression | |
| 594 while it does input. (The exception is when @kbd{C-h} is meaningful | |
| 595 input.) Evaluating this expression should result in a string that | |
| 596 explains what the input is for and how to enter it properly. | |
| 597 | |
| 598 Entry to the minibuffer binds this variable to the value of | |
| 599 @code{minibuffer-help-form} (@pxref{Minibuffer Misc}). | |
| 600 @end defvar | |
| 601 | |
| 602 @defvar prefix-help-command | |
| 603 This variable holds a function to print help for a prefix character. | |
| 604 The function is called when the user types a prefix key followed by the | |
| 605 help character, and the help character has no binding after that prefix. | |
| 606 The variable's default value is @code{describe-prefix-bindings}. | |
| 607 @end defvar | |
| 608 | |
| 444 | 609 @deffn Command describe-prefix-bindings |
| 428 | 610 This function calls @code{describe-bindings} to display a list of all |
| 611 the subcommands of the prefix key of the most recent key sequence. The | |
| 612 prefix described consists of all but the last event of that key | |
| 613 sequence. (The last event is, presumably, the help character.) | |
| 444 | 614 @end deffn |
| 428 | 615 |
| 616 The following two functions are found in the library @file{helper}. | |
| 617 They are for modes that want to provide help without relinquishing | |
| 618 control, such as the ``electric'' modes. You must load that library | |
| 619 with @code{(require 'helper)} in order to use them. Their names begin | |
| 620 with @samp{Helper} to distinguish them from the ordinary help functions. | |
| 621 | |
| 622 @deffn Command Helper-describe-bindings | |
| 623 This command pops up a window displaying a help buffer containing a | |
| 624 listing of all of the key bindings from both the local and global keymaps. | |
| 625 It works by calling @code{describe-bindings}. | |
| 626 @end deffn | |
| 627 | |
| 628 @deffn Command Helper-help | |
| 629 This command provides help for the current mode. It prompts the user | |
| 630 in the minibuffer with the message @samp{Help (Type ? for further | |
| 631 options)}, and then provides assistance in finding out what the key | |
| 632 bindings are, and what the mode is intended for. It returns @code{nil}. | |
| 633 | |
| 634 This can be customized by changing the map @code{Helper-help-map}. | |
| 635 @end deffn | |
| 636 | |
| 637 @ignore @c Not in XEmacs currently | |
| 638 @c Emacs 19 feature | |
| 639 @defmac make-help-screen fname help-line help-text help-map | |
| 640 This macro defines a help command named @var{fname} that acts like a | |
| 641 prefix key that shows a list of the subcommands it offers. | |
| 642 | |
| 643 When invoked, @var{fname} displays @var{help-text} in a window, then | |
| 644 reads and executes a key sequence according to @var{help-map}. The | |
| 645 string @var{help-text} should describe the bindings available in | |
| 646 @var{help-map}. | |
| 647 | |
| 648 The command @var{fname} is defined to handle a few events itself, by | |
| 649 scrolling the display of @var{help-text}. When @var{fname} reads one of | |
| 650 those special events, it does the scrolling and then reads another | |
| 651 event. When it reads an event that is not one of those few, and which | |
| 652 has a binding in @var{help-map}, it executes that key's binding and | |
| 653 then returns. | |
| 654 | |
| 655 The argument @var{help-line} should be a single-line summary of the | |
| 656 alternatives in @var{help-map}. In the current version of Emacs, this | |
| 657 argument is used only if you set the option @code{three-step-help} to | |
| 658 @code{t}. | |
| 659 @end defmac | |
| 660 | |
| 661 @defopt three-step-help | |
| 662 If this variable is non-@code{nil}, commands defined with | |
| 663 @code{make-help-screen} display their @var{help-line} strings in the | |
| 664 echo area at first, and display the longer @var{help-text} strings only | |
| 665 if the user types the help character again. | |
| 666 @end defopt | |
| 667 @end ignore | |
| 668 | |
| 669 @node Obsoleteness | |
| 670 @section Obsoleteness | |
| 671 | |
| 672 As you add functionality to a package, you may at times want to | |
| 673 replace an older function with a new one. To preserve compatibility | |
| 674 with existing code, the older function needs to still exist; but | |
| 675 users of that function should be told to use the newer one instead. | |
| 676 XEmacs Lisp lets you mark a function or variable as @dfn{obsolete}, | |
| 677 and indicate what should be used instead. | |
| 678 | |
| 2444 | 679 @deffn Command make-obsolete function new &optional when |
| 428 | 680 This function indicates that @var{function} is an obsolete function, |
| 681 and the function @var{new} should be used instead. The byte compiler | |
| 682 will issue a warning to this effect when it encounters a usage of the | |
| 683 older function, and the help system will also note this in the function's | |
| 684 documentation. @var{new} can also be a string (if there is not a single | |
| 685 function with the same functionality any more), and should be a descriptive | |
| 686 statement, such as "use @var{foo} or @var{bar} instead" or "this function is | |
| 2444 | 687 unnecessary". If provided, @var{when} should be a string indicating when |
| 688 the function was first made obsolete, for example a date or a release | |
| 689 number. | |
| 444 | 690 @end deffn |
| 428 | 691 |
| 444 | 692 @deffn Command make-obsolete-variable variable new |
| 428 | 693 This is like @code{make-obsolete} but is for variables instead of functions. |
| 444 | 694 @end deffn |
| 428 | 695 |
| 696 @defun define-obsolete-function-alias oldfun newfun | |
| 697 This function combines @code{make-obsolete} and @code{define-function}, | |
| 698 declaring @var{oldfun} to be an obsolete variant of @var{newfun} and | |
| 699 defining @var{oldfun} as an alias for @var{newfun}. | |
| 700 @end defun | |
| 701 | |
| 702 @defun define-obsolete-variable-alias oldvar newvar | |
| 703 This is like @code{define-obsolete-function-alias} but for variables. | |
| 704 @end defun | |
| 705 | |
| 706 Note that you should not normally put obsoleteness information | |
| 707 explicitly in a function or variable's doc string. The obsoleteness | |
| 708 information that you specify using the above functions will be displayed | |
| 709 whenever the doc string is displayed, and by adding it explicitly the | |
| 710 result is redundancy. | |
| 711 | |
| 712 Also, if an obsolete function is substantially the same as a newer one | |
| 713 but is not actually an alias, you should consider omitting the doc | |
| 714 string entirely (use a null string @samp{""} as the doc string). That | |
| 715 way, the user is told about the obsoleteness and is forced to look at | |
| 716 the documentation of the new function, making it more likely that he | |
| 717 will use the new function. | |
| 718 | |
| 719 @defun function-obsoleteness-doc function | |
| 720 If @var{function} is obsolete, this function returns a string describing | |
| 721 this. This is the message that is printed out during byte compilation | |
| 722 or in the function's documentation. If @var{function} is not obsolete, | |
| 723 @code{nil} is returned. | |
| 724 @end defun | |
| 725 | |
| 726 @defun variable-obsoleteness-doc variable | |
| 727 This is like @code{function-obsoleteness-doc} but for variables. | |
| 728 @end defun | |
| 729 | |
| 730 The obsoleteness information is stored internally by putting a property | |
| 731 @code{byte-obsolete-info} (for functions) or | |
| 732 @code{byte-obsolete-variable} (for variables) on the symbol that | |
| 733 specifies the obsolete function or variable. For more information, see | |
| 734 the implementation of @code{make-obsolete} and | |
| 735 @code{make-obsolete-variable} in | |
| 736 @file{lisp/bytecomp/bytecomp-runtime.el}. |