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8a93676d SB |
1 | |
2 | =for comment | |
3 | This document is in Pod format. To read this, use a Pod formatter, | |
4 | like "perldoc perlpod". | |
5 | ||
a0d0e21e | 6 | =head1 NAME |
d74e8afc | 7 | X<POD> X<plain old documentation> |
a0d0e21e | 8 | |
8a93676d | 9 | perlpod - the Plain Old Documentation format |
a0d0e21e LW |
10 | |
11 | =head1 DESCRIPTION | |
12 | ||
8a93676d SB |
13 | Pod is a simple-to-use markup language used for writing documentation |
14 | for Perl, Perl programs, and Perl modules. | |
15 | ||
16 | Translators are available for converting Pod to various formats | |
17 | like plain text, HTML, man pages, and more. | |
18 | ||
19 | Pod markup consists of three basic kinds of paragraphs: | |
20 | L<ordinary|/"Ordinary Paragraph">, | |
21 | L<verbatim|/"Verbatim Paragraph">, and | |
22 | L<command|/"Command Paragraph">. | |
23 | ||
24 | ||
25 | =head2 Ordinary Paragraph | |
d74e8afc | 26 | X<POD, ordinary paragraph> |
8a93676d SB |
27 | |
28 | Most paragraphs in your documentation will be ordinary blocks | |
29 | of text, like this one. You can simply type in your text without | |
30 | any markup whatsoever, and with just a blank line before and | |
31 | after. When it gets formatted, it will undergo minimal formatting, | |
32 | like being rewrapped, probably put into a proportionally spaced | |
33 | font, and maybe even justified. | |
34 | ||
35 | You can use formatting codes in ordinary paragraphs, for B<bold>, | |
36 | I<italic>, C<code-style>, L<hyperlinks|perlfaq>, and more. Such | |
37 | codes are explained in the "L<Formatting Codes|/"Formatting Codes">" | |
38 | section, below. | |
39 | ||
a0d0e21e | 40 | |
b74bceb9 | 41 | =head2 Verbatim Paragraph |
d74e8afc | 42 | X<POD, verbatim paragraph> X<verbatim> |
a0d0e21e | 43 | |
8a93676d SB |
44 | Verbatim paragraphs are usually used for presenting a codeblock or |
45 | other text which does not require any special parsing or formatting, | |
46 | and which shouldn't be wrapped. | |
47 | ||
48 | A verbatim paragraph is distinguished by having its first character | |
49 | be a space or a tab. (And commonly, all its lines begin with spaces | |
50 | and/or tabs.) It should be reproduced exactly, with tabs assumed to | |
51 | be on 8-column boundaries. There are no special formatting codes, | |
52 | so you can't italicize or anything like that. A \ means \, and | |
53 | nothing else. | |
54 | ||
a0d0e21e | 55 | |
b74bceb9 | 56 | =head2 Command Paragraph |
d74e8afc | 57 | X<POD, command> |
b74bceb9 | 58 | |
8a93676d SB |
59 | A command paragraph is used for special treatment of whole chunks |
60 | of text, usually as headings or parts of lists. | |
61 | ||
62 | All command paragraphs (which are typically only one line long) start | |
63 | with "=", followed by an identifier, followed by arbitrary text that | |
64 | the command can use however it pleases. Currently recognized commands | |
65 | are | |
a0d0e21e | 66 | |
2757242d | 67 | =pod |
8a93676d SB |
68 | =head1 Heading Text |
69 | =head2 Heading Text | |
70 | =head3 Heading Text | |
71 | =head4 Heading Text | |
ee511750 S |
72 | =head5 Heading Text |
73 | =head6 Heading Text | |
8a93676d SB |
74 | =over indentlevel |
75 | =item stuff | |
a0d0e21e | 76 | =back |
8a93676d SB |
77 | =begin format |
78 | =end format | |
79 | =for format text... | |
2757242d YO |
80 | =encoding type |
81 | =cut | |
8a93676d SB |
82 | |
83 | To explain them each in detail: | |
84 | ||
85 | =over | |
86 | ||
87 | =item C<=head1 I<Heading Text>> | |
ee511750 S |
88 | X<=head1> X<=head2> X<=head3> X<=head4> X<=head5> X<=head6> |
89 | X<head1> X<head2> X<head3> X<head4> X<head5> X<head6> | |
cb1a09d0 | 90 | |
8a93676d | 91 | =item C<=head2 I<Heading Text>> |
b74bceb9 | 92 | |
8a93676d | 93 | =item C<=head3 I<Heading Text>> |
b74bceb9 | 94 | |
8a93676d | 95 | =item C<=head4 I<Heading Text>> |
b74bceb9 | 96 | |
ee511750 S |
97 | =item C<=head5 I<Heading Text>> |
98 | ||
99 | =item C<=head6 I<Heading Text>> | |
100 | ||
101 | Head1 through head6 produce headings, head1 being the highest | |
8a93676d SB |
102 | level. The text in the rest of this paragraph is the content of the |
103 | heading. For example: | |
cb1a09d0 | 104 | |
8a93676d | 105 | =head2 Object Attributes |
b74bceb9 | 106 | |
684c7e37 BF |
107 | The text "Object Attributes" comprises the heading there. |
108 | The text in these heading commands can use formatting codes, as seen here: | |
b74bceb9 | 109 | |
8a93676d | 110 | =head2 Possible Values for C<$/> |
c6b85e5d | 111 | |
8a93676d SB |
112 | Such commands are explained in the |
113 | "L<Formatting Codes|/"Formatting Codes">" section, below. | |
c6b85e5d | 114 | |
ee511750 S |
115 | Note that C<head5> and C<head6> were introduced in 2020 and in |
116 | L<Pod::Simple> 3.41, released in October 2020, so they might not be | |
117 | supported on the Pod parser you use. | |
118 | ||
8a93676d | 119 | =item C<=over I<indentlevel>> |
d74e8afc | 120 | X<=over> X<=item> X<=back> X<over> X<item> X<back> |
cb1a09d0 | 121 | |
8a93676d | 122 | =item C<=item I<stuff...>> |
b74bceb9 | 123 | |
8a93676d | 124 | =item C<=back> |
b74bceb9 | 125 | |
8a93676d SB |
126 | Item, over, and back require a little more explanation: "=over" starts |
127 | a region specifically for the generation of a list using "=item" | |
128 | commands, or for indenting (groups of) normal paragraphs. At the end | |
129 | of your list, use "=back" to end it. The I<indentlevel> option to | |
130 | "=over" indicates how far over to indent, generally in ems (where | |
131 | one em is the width of an "M" in the document's base font) or roughly | |
132 | comparable units; if there is no I<indentlevel> option, it defaults | |
133 | to four. (And some formatters may just ignore whatever I<indentlevel> | |
134 | you provide.) In the I<stuff> in C<=item I<stuff...>>, you may | |
135 | use formatting codes, as seen here: | |
b74bceb9 | 136 | |
8a93676d | 137 | =item Using C<$|> to Control Buffering |
cb1a09d0 | 138 | |
8a93676d SB |
139 | Such commands are explained in the |
140 | "L<Formatting Codes|/"Formatting Codes">" section, below. | |
b74bceb9 | 141 | |
8a93676d SB |
142 | Note also that there are some basic rules to using "=over" ... |
143 | "=back" regions: | |
b74bceb9 | 144 | |
8a93676d | 145 | =over |
b74bceb9 | 146 | |
8a93676d SB |
147 | =item * |
148 | ||
149 | Don't use "=item"s outside of an "=over" ... "=back" region. | |
150 | ||
151 | =item * | |
c7c9f956 | 152 | |
8a93676d SB |
153 | The first thing after the "=over" command should be an "=item", unless |
154 | there aren't going to be any items at all in this "=over" ... "=back" | |
155 | region. | |
156 | ||
157 | =item * | |
158 | ||
159 | Don't put "=headI<n>" commands inside an "=over" ... "=back" region. | |
160 | ||
161 | =item * | |
162 | ||
163 | And perhaps most importantly, keep the items consistent: either use | |
164 | "=item *" for all of them, to produce bullets; or use "=item 1.", | |
165 | "=item 2.", etc., to produce numbered lists; or use "=item foo", | |
ac036724 | 166 | "=item bar", etc.--namely, things that look nothing like bullets or |
ba77fc59 KW |
167 | numbers. (If you have a list that contains both: 1) things that don't |
168 | look like bullets nor numbers, plus 2) things that do, you should | |
169 | preface the bullet- or number-like items with C<ZE<lt>E<gt>>. See | |
170 | L<ZE<lt>E<gt>|/ZE<lt>E<gt> -- a null (zero-effect) formatting code> | |
171 | below for an example.) | |
8a93676d SB |
172 | |
173 | If you start with bullets or numbers, stick with them, as | |
174 | formatters use the first "=item" type to decide how to format the | |
175 | list. | |
176 | ||
177 | =back | |
178 | ||
179 | =item C<=cut> | |
d74e8afc | 180 | X<=cut> X<cut> |
8a93676d SB |
181 | |
182 | To end a Pod block, use a blank line, | |
183 | then a line beginning with "=cut", and a blank | |
184 | line after it. This lets Perl (and the Pod formatter) know that | |
185 | this is where Perl code is resuming. (The blank line before the "=cut" | |
186 | is not technically necessary, but many older Pod processors require it.) | |
187 | ||
188 | =item C<=pod> | |
d74e8afc | 189 | X<=pod> X<pod> |
8a93676d SB |
190 | |
191 | The "=pod" command by itself doesn't do much of anything, but it | |
192 | signals to Perl (and Pod formatters) that a Pod block starts here. A | |
193 | Pod block starts with I<any> command paragraph, so a "=pod" command is | |
194 | usually used just when you want to start a Pod block with an ordinary | |
195 | paragraph or a verbatim paragraph. For example: | |
196 | ||
197 | =item stuff() | |
210b36aa | 198 | |
8a93676d | 199 | This function does stuff. |
210b36aa | 200 | |
8a93676d | 201 | =cut |
210b36aa | 202 | |
8a93676d SB |
203 | sub stuff { |
204 | ... | |
205 | } | |
210b36aa | 206 | |
8a93676d | 207 | =pod |
210b36aa | 208 | |
8a93676d | 209 | Remember to check its return value, as in: |
210b36aa AMS |
210 | |
211 | stuff() || die "Couldn't do stuff!"; | |
212 | ||
8a93676d SB |
213 | =cut |
214 | ||
215 | =item C<=begin I<formatname>> | |
d74e8afc | 216 | X<=begin> X<=end> X<=for> X<begin> X<end> X<for> |
8a93676d SB |
217 | |
218 | =item C<=end I<formatname>> | |
219 | ||
220 | =item C<=for I<formatname> I<text...>> | |
221 | ||
222 | For, begin, and end will let you have regions of text/code/data that | |
223 | are not generally interpreted as normal Pod text, but are passed | |
224 | directly to particular formatters, or are otherwise special. A | |
225 | formatter that can use that format will use the region, otherwise it | |
226 | will be completely ignored. | |
227 | ||
228 | A command "=begin I<formatname>", some paragraphs, and a | |
353c6505 | 229 | command "=end I<formatname>", mean that the text/data in between |
8a93676d SB |
230 | is meant for formatters that understand the special format |
231 | called I<formatname>. For example, | |
232 | ||
233 | =begin html | |
210b36aa | 234 | |
8a93676d | 235 | <hr> <img src="thang.png"> |
c7c9f956 | 236 | <p> This is a raw HTML paragraph </p> |
210b36aa | 237 | |
8a93676d SB |
238 | =end html |
239 | ||
240 | The command "=for I<formatname> I<text...>" | |
241 | specifies that the remainder of just this paragraph (starting | |
242 | right after I<formatname>) is in that special format. | |
243 | ||
244 | =for html <hr> <img src="thang.png"> | |
245 | <p> This is a raw HTML paragraph </p> | |
246 | ||
247 | This means the same thing as the above "=begin html" ... "=end html" | |
248 | region. | |
c7c9f956 | 249 | |
8a93676d SB |
250 | That is, with "=for", you can have only one paragraph's worth |
251 | of text (i.e., the text in "=foo targetname text..."), but with | |
252 | "=begin targetname" ... "=end targetname", you can have any amount | |
1cecf2c0 | 253 | of stuff in between. (Note that there still must be a blank line |
8a93676d | 254 | after the "=begin" command and a blank line before the "=end" |
943fc58e | 255 | command.) |
c7c9f956 KA |
256 | |
257 | Here are some examples of how to use these: | |
258 | ||
8a93676d SB |
259 | =begin html |
260 | ||
261 | <br>Figure 1.<br><IMG SRC="figure1.png"><br> | |
262 | ||
263 | =end html | |
264 | ||
265 | =begin text | |
266 | ||
267 | --------------- | |
268 | | foo | | |
269 | | bar | | |
270 | --------------- | |
a6006777 | 271 | |
8a93676d | 272 | ^^^^ Figure 1. ^^^^ |
a6006777 | 273 | |
8a93676d | 274 | =end text |
a6006777 | 275 | |
8a93676d SB |
276 | Some format names that formatters currently are known to accept |
277 | include "roff", "man", "latex", "tex", "text", and "html". (Some | |
278 | formatters will treat some of these as synonyms.) | |
a6006777 | 279 | |
8a93676d SB |
280 | A format name of "comment" is common for just making notes (presumably |
281 | to yourself) that won't appear in any formatted version of the Pod | |
282 | document: | |
a6006777 | 283 | |
8a93676d SB |
284 | =for comment |
285 | Make sure that all the available options are documented! | |
a6006777 | 286 | |
8a93676d SB |
287 | Some I<formatnames> will require a leading colon (as in |
288 | C<"=for :formatname">, or | |
289 | C<"=begin :formatname" ... "=end :formatname">), | |
290 | to signal that the text is not raw data, but instead I<is> Pod text | |
291 | (i.e., possibly containing formatting codes) that's just not for | |
292 | normal formatting (e.g., may not be a normal-use paragraph, but might | |
293 | be for formatting as a footnote). | |
c7c9f956 | 294 | |
a179871b | 295 | =item C<=encoding I<encodingname>> |
d74e8afc | 296 | X<=encoding> X<encoding> |
a179871b SB |
297 | |
298 | This command is used for declaring the encoding of a document. Most | |
a0879bf8 KW |
299 | users won't need this; but if your encoding isn't US-ASCII, |
300 | then put a C<=encoding I<encodingname>> command very early in the document so | |
a179871b SB |
301 | that pod formatters will know how to decode the document. For |
302 | I<encodingname>, use a name recognized by the L<Encode::Supported> | |
8f226aee DW |
303 | module. Some pod formatters may try to guess between a Latin-1 or |
304 | CP-1252 versus | |
a0879bf8 KW |
305 | UTF-8 encoding, but they may guess wrong. It's best to be explicit if |
306 | you use anything besides strict ASCII. Examples: | |
307 | ||
308 | =encoding latin1 | |
a179871b SB |
309 | |
310 | =encoding utf8 | |
311 | ||
312 | =encoding koi8-r | |
f703fc96 | 313 | |
a179871b | 314 | =encoding ShiftJIS |
f703fc96 | 315 | |
a179871b SB |
316 | =encoding big5 |
317 | ||
7a9a6fa1 DJ |
318 | C<=encoding> affects the whole document, and must occur only once. |
319 | ||
e023b52d KW |
320 | =back |
321 | ||
322 | And don't forget, all commands but C<=encoding> last up | |
8a93676d SB |
323 | until the end of its I<paragraph>, not its line. So in the |
324 | examples below, you can see that every command needs the blank | |
556e7d6c KW |
325 | line after it, to end its paragraph. (And some older Pod translators |
326 | may require the C<=encoding> line to have a following blank line as | |
327 | well, even though it should be legal to omit.) | |
cb1a09d0 AD |
328 | |
329 | Some examples of lists include: | |
330 | ||
8a93676d SB |
331 | =over |
332 | ||
333 | =item * | |
334 | ||
335 | First item | |
336 | ||
337 | =item * | |
338 | ||
339 | Second item | |
340 | ||
341 | =back | |
342 | ||
343 | =over | |
344 | ||
345 | =item Foo() | |
346 | ||
347 | Description of Foo function | |
348 | ||
349 | =item Bar() | |
cb1a09d0 | 350 | |
8a93676d | 351 | Description of Bar function |
cb1a09d0 | 352 | |
8a93676d | 353 | =back |
cb1a09d0 | 354 | |
cb1a09d0 | 355 | |
8a93676d | 356 | =head2 Formatting Codes |
d74e8afc ITB |
357 | X<POD, formatting code> X<formatting code> |
358 | X<POD, interior sequence> X<interior sequence> | |
cb1a09d0 | 359 | |
8a93676d SB |
360 | In ordinary paragraphs and in some command paragraphs, various |
361 | formatting codes (a.k.a. "interior sequences") can be used: | |
cb1a09d0 | 362 | |
8a93676d SB |
363 | =for comment |
364 | "interior sequences" is such an opaque term. | |
365 | Prefer "formatting codes" instead. | |
cb1a09d0 | 366 | |
8a93676d | 367 | =over |
cb1a09d0 | 368 | |
8a93676d | 369 | =item C<IE<lt>textE<gt>> -- italic text |
d74e8afc | 370 | X<I> X<< IZ<><> >> X<POD, formatting code, italic> X<italic> |
cb1a09d0 | 371 | |
8a93676d SB |
372 | Used for emphasis ("C<be IE<lt>careful!E<gt>>") and parameters |
373 | ("C<redo IE<lt>LABELE<gt>>") | |
374 | ||
375 | =item C<BE<lt>textE<gt>> -- bold text | |
d74e8afc | 376 | X<B> X<< BZ<><> >> X<POD, formatting code, bold> X<bold> |
8a93676d SB |
377 | |
378 | Used for switches ("C<perl's BE<lt>-nE<gt> switch>"), programs | |
379 | ("C<some systems provide a BE<lt>chfnE<gt> for that>"), | |
380 | emphasis ("C<be BE<lt>careful!E<gt>>"), and so on | |
381 | ("C<and that feature is known as BE<lt>autovivificationE<gt>>"). | |
382 | ||
383 | =item C<CE<lt>codeE<gt>> -- code text | |
d74e8afc | 384 | X<C> X<< CZ<><> >> X<POD, formatting code, code> X<code> |
8a93676d SB |
385 | |
386 | Renders code in a typewriter font, or gives some other indication that | |
387 | this represents program text ("C<CE<lt>gmtime($^T)E<gt>>") or some other | |
388 | form of computerese ("C<CE<lt>drwxr-xr-xE<gt>>"). | |
389 | ||
390 | =item C<LE<lt>nameE<gt>> -- a hyperlink | |
d74e8afc | 391 | X<L> X<< LZ<><> >> X<POD, formatting code, hyperlink> X<hyperlink> |
8a93676d SB |
392 | |
393 | There are various syntaxes, listed below. In the syntaxes given, | |
394 | C<text>, C<name>, and C<section> cannot contain the characters | |
395 | '/' and '|'; and any '<' or '>' should be matched. | |
396 | ||
397 | =over | |
398 | ||
399 | =item * | |
cb1a09d0 | 400 | |
8a93676d | 401 | C<LE<lt>nameE<gt>> |
cb1a09d0 | 402 | |
8a93676d SB |
403 | Link to a Perl manual page (e.g., C<LE<lt>Net::PingE<gt>>). Note |
404 | that C<name> should not contain spaces. This syntax | |
e1020413 | 405 | is also occasionally used for references to Unix man pages, as in |
8a93676d SB |
406 | C<LE<lt>crontab(5)E<gt>>. |
407 | ||
408 | =item * | |
409 | ||
410 | C<LE<lt>name/"sec"E<gt>> or C<LE<lt>name/secE<gt>> | |
411 | ||
412 | Link to a section in other manual page. E.g., | |
413 | C<LE<lt>perlsyn/"For Loops"E<gt>> | |
414 | ||
415 | =item * | |
416 | ||
b41aadf2 | 417 | C<LE<lt>/"sec"E<gt>> or C<LE<lt>/secE<gt>> |
8a93676d SB |
418 | |
419 | Link to a section in this manual page. E.g., | |
420 | C<LE<lt>/"Object Methods"E<gt>> | |
a0d0e21e | 421 | |
b74bceb9 AB |
422 | =back |
423 | ||
8a93676d SB |
424 | A section is started by the named heading or item. For |
425 | example, C<LE<lt>perlvar/$.E<gt>> or C<LE<lt>perlvar/"$."E<gt>> both | |
426 | link to the section started by "C<=item $.>" in perlvar. And | |
427 | C<LE<lt>perlsyn/For LoopsE<gt>> or C<LE<lt>perlsyn/"For Loops"E<gt>> | |
428 | both link to the section started by "C<=head2 For Loops>" | |
429 | in perlsyn. | |
430 | ||
431 | To control what text is used for display, you | |
432 | use "C<LE<lt>text|...E<gt>>", as in: | |
433 | ||
434 | =over | |
435 | ||
436 | =item * | |
437 | ||
438 | C<LE<lt>text|nameE<gt>> | |
439 | ||
440 | Link this text to that manual page. E.g., | |
441 | C<LE<lt>Perl Error Messages|perldiagE<gt>> | |
442 | ||
443 | =item * | |
444 | ||
445 | C<LE<lt>text|name/"sec"E<gt>> or C<LE<lt>text|name/secE<gt>> | |
446 | ||
447 | Link this text to that section in that manual page. E.g., | |
8325efec | 448 | C<LE<lt>postfix "if"|perlsyn/"Statement Modifiers"E<gt>> |
8a93676d SB |
449 | |
450 | =item * | |
451 | ||
452 | C<LE<lt>text|/"sec"E<gt>> or C<LE<lt>text|/secE<gt>> | |
453 | or C<LE<lt>text|"sec"E<gt>> | |
454 | ||
455 | Link this text to that section in this manual page. E.g., | |
456 | C<LE<lt>the various attributes|/"Member Data"E<gt>> | |
457 | ||
458 | =back | |
459 | ||
460 | Or you can link to a web page: | |
461 | ||
462 | =over | |
463 | ||
464 | =item * | |
465 | ||
466 | C<LE<lt>scheme:...E<gt>> | |
467 | ||
f6e963e4 RS |
468 | C<LE<lt>text|scheme:...E<gt>> |
469 | ||
470 | Links to an absolute URL. For example, C<LE<lt>http://www.perl.org/E<gt>> or | |
471 | C<LE<lt>The Perl Home Page|http://www.perl.org/E<gt>>. | |
8a93676d SB |
472 | |
473 | =back | |
474 | ||
475 | =item C<EE<lt>escapeE<gt>> -- a character escape | |
d74e8afc | 476 | X<E> X<< EZ<><> >> X<POD, formatting code, escape> X<escape> |
8a93676d SB |
477 | |
478 | Very similar to HTML/XML C<&I<foo>;> "entity references": | |
479 | ||
480 | =over | |
481 | ||
482 | =item * | |
483 | ||
484 | C<EE<lt>ltE<gt>> -- a literal E<lt> (less than) | |
485 | ||
486 | =item * | |
487 | ||
488 | C<EE<lt>gtE<gt>> -- a literal E<gt> (greater than) | |
489 | ||
490 | =item * | |
491 | ||
492 | C<EE<lt>verbarE<gt>> -- a literal | (I<ver>tical I<bar>) | |
493 | ||
494 | =item * | |
495 | ||
1f1448d9 | 496 | C<EE<lt>solE<gt>> -- a literal / (I<sol>idus) |
8a93676d SB |
497 | |
498 | The above four are optional except in other formatting codes, | |
499 | notably C<LE<lt>...E<gt>>, and when preceded by a | |
500 | capital letter. | |
501 | ||
502 | =item * | |
503 | ||
504 | C<EE<lt>htmlnameE<gt>> | |
505 | ||
506 | Some non-numeric HTML entity name, such as C<EE<lt>eacuteE<gt>>, | |
507 | meaning the same thing as C<é> in HTML -- i.e., a lowercase | |
508 | e with an acute (/-shaped) accent. | |
509 | ||
510 | =item * | |
511 | ||
512 | C<EE<lt>numberE<gt>> | |
513 | ||
1a3afb4f | 514 | The ASCII/Latin-1/Unicode character with that number. A |
8a93676d SB |
515 | leading "0x" means that I<number> is hex, as in |
516 | C<EE<lt>0x201EE<gt>>. A leading "0" means that I<number> is octal, | |
517 | as in C<EE<lt>075E<gt>>. Otherwise I<number> is interpreted as being | |
518 | in decimal, as in C<EE<lt>181E<gt>>. | |
519 | ||
520 | Note that older Pod formatters might not recognize octal or | |
521 | hex numeric escapes, and that many formatters cannot reliably | |
522 | render characters above 255. (Some formatters may even have | |
8f226aee | 523 | to use compromised renderings of Latin-1/CP-1252 characters, like |
8a93676d SB |
524 | rendering C<EE<lt>eacuteE<gt>> as just a plain "e".) |
525 | ||
526 | =back | |
527 | ||
528 | =item C<FE<lt>filenameE<gt>> -- used for filenames | |
d74e8afc | 529 | X<F> X<< FZ<><> >> X<POD, formatting code, filename> X<filename> |
8a93676d SB |
530 | |
531 | Typically displayed in italics. Example: "C<FE<lt>.cshrcE<gt>>" | |
532 | ||
533 | =item C<SE<lt>textE<gt>> -- text contains non-breaking spaces | |
d74e8afc ITB |
534 | X<S> X<< SZ<><> >> X<POD, formatting code, non-breaking space> |
535 | X<non-breaking space> | |
8a93676d SB |
536 | |
537 | This means that the words in I<text> should not be broken | |
538 | across lines. Example: S<C<SE<lt>$x ? $y : $zE<gt>>>. | |
539 | ||
540 | =item C<XE<lt>topic nameE<gt>> -- an index entry | |
d74e8afc | 541 | X<X> X<< XZ<><> >> X<POD, formatting code, index entry> X<index entry> |
8a93676d SB |
542 | |
543 | This is ignored by most formatters, but some may use it for building | |
544 | indexes. It always renders as empty-string. | |
545 | Example: C<XE<lt>absolutizing relative URLsE<gt>> | |
546 | ||
547 | =item C<ZE<lt>E<gt>> -- a null (zero-effect) formatting code | |
d74e8afc | 548 | X<Z> X<< ZZ<><> >> X<POD, formatting code, null> X<null> |
8a93676d SB |
549 | |
550 | This is rarely used. It's one way to get around using an | |
551 | EE<lt>...E<gt> code sometimes. For example, instead of | |
552 | "C<NEE<lt>ltE<gt>3>" (for "NE<lt>3") you could write | |
553 | "C<NZE<lt>E<gt>E<lt>3>" (the "ZE<lt>E<gt>" breaks up the "N" and | |
554 | the "E<lt>" so they can't be considered | |
6c1c521a | 555 | the part of a (fictitious) "NE<lt>...E<gt>" code). |
8a93676d | 556 | |
ba77fc59 KW |
557 | Another use is to indicate that I<stuff> in C<=item ZE<lt>E<gt>I<stuff...>> |
558 | is not to be considered to be a bullet or number. For example, | |
559 | without the C<ZE<lt>E<gt>>, the line | |
560 | ||
561 | =item Z<>500 Server error | |
562 | ||
563 | could possibly be parsed as an item in a numbered list when it isn't | |
564 | meant to be. | |
565 | ||
566 | Still another use is to maintain visual space between C<=item> lines. | |
567 | If you specify | |
568 | ||
569 | =item foo | |
570 | ||
571 | =item bar | |
572 | ||
573 | it will typically get rendered as | |
574 | ||
575 | foo | |
576 | bar | |
577 | ||
578 | That may be what you want, but if what you really want is | |
579 | ||
580 | foo | |
581 | ||
582 | bar | |
583 | ||
584 | you can use C<ZE<lt>E<gt>> to accomplish that | |
585 | ||
586 | =item foo | |
587 | ||
588 | Z<> | |
589 | ||
590 | =item bar | |
591 | ||
8a93676d SB |
592 | =for comment |
593 | This was formerly explained as a "zero-width character". But it in | |
594 | most parser models, it parses to nothing at all, as opposed to parsing | |
595 | as if it were a E<zwnj> or E<zwj>, which are REAL zero-width characters. | |
596 | So "width" and "character" are exactly the wrong words. | |
597 | ||
598 | =back | |
599 | ||
600 | Most of the time, you will need only a single set of angle brackets to | |
601 | delimit the beginning and end of formatting codes. However, | |
602 | sometimes you will want to put a real right angle bracket (a | |
603 | greater-than sign, '>') inside of a formatting code. This is particularly | |
604 | common when using a formatting code to provide a different font-type for a | |
605 | snippet of code. As with all things in Perl, there is more than | |
606 | one way to do it. One way is to simply escape the closing bracket | |
607 | using an C<E> code: | |
5455df32 GS |
608 | |
609 | C<$a E<lt>=E<gt> $b> | |
610 | ||
611 | This will produce: "C<$a E<lt>=E<gt> $b>" | |
612 | ||
8a93676d | 613 | A more readable, and perhaps more "plain" way is to use an alternate |
8162142b JD |
614 | set of delimiters that doesn't require a single ">" to be escaped. |
615 | Doubled angle brackets ("<<" and ">>") may be used I<if and only if there is | |
8a93676d SB |
616 | whitespace right after the opening delimiter and whitespace right |
617 | before the closing delimiter!> For example, the following will | |
618 | do the trick: | |
d74e8afc | 619 | X<POD, formatting code, escaping with multiple brackets> |
5455df32 GS |
620 | |
621 | C<< $a <=> $b >> | |
622 | ||
623 | In fact, you can use as many repeated angle-brackets as you like so | |
624 | long as you have the same number of them in the opening and closing | |
625 | delimiters, and make sure that whitespace immediately follows the last | |
8a93676d SB |
626 | '<' of the opening delimiter, and immediately precedes the first '>' |
627 | of the closing delimiter. (The whitespace is ignored.) So the | |
628 | following will also work: | |
d74e8afc | 629 | X<POD, formatting code, escaping with multiple brackets> |
5455df32 GS |
630 | |
631 | C<<< $a <=> $b >>> | |
8a93676d | 632 | C<<<< $a <=> $b >>>> |
5455df32 | 633 | |
8a93676d SB |
634 | And they all mean exactly the same as this: |
635 | ||
636 | C<$a E<lt>=E<gt> $b> | |
637 | ||
a3d78747 RS |
638 | The multiple-bracket form does not affect the interpretation of the contents of |
639 | the formatting code, only how it must end. That means that the examples above | |
640 | are also exactly the same as this: | |
641 | ||
642 | C<< $a E<lt>=E<gt> $b >> | |
643 | ||
8a93676d SB |
644 | As a further example, this means that if you wanted to put these bits of |
645 | code in C<C> (code) style: | |
646 | ||
647 | open(X, ">>thing.dat") || die $! | |
648 | $foo->bar(); | |
649 | ||
650 | you could do it like so: | |
651 | ||
652 | C<<< open(X, ">>thing.dat") || die $! >>> | |
653 | C<< $foo->bar(); >> | |
5455df32 | 654 | |
8a93676d SB |
655 | which is presumably easier to read than the old way: |
656 | ||
657 | C<open(X, "E<gt>E<gt>thing.dat") || die $!> | |
c58e3c1c | 658 | C<$foo-E<gt>bar();> |
8a93676d SB |
659 | |
660 | This is currently supported by pod2text (Pod::Text), pod2man (Pod::Man), | |
661 | and any other pod2xxx or Pod::Xxxx translators that use | |
662 | Pod::Parser 1.093 or later, or Pod::Tree 1.02 or later. | |
5455df32 | 663 | |
b74bceb9 | 664 | =head2 The Intent |
d74e8afc | 665 | X<POD, intent of> |
3141265f | 666 | |
8a93676d SB |
667 | The intent is simplicity of use, not power of expression. Paragraphs |
668 | look like paragraphs (block format), so that they stand out | |
669 | visually, and so that I could run them through C<fmt> easily to reformat | |
670 | them (that's F7 in my version of B<vi>, or Esc Q in my version of | |
671 | B<emacs>). I wanted the translator to always leave the C<'> and C<`> and | |
672 | C<"> quotes alone, in verbatim mode, so I could slurp in a | |
673 | working program, shift it over four spaces, and have it print out, er, | |
674 | verbatim. And presumably in a monospace font. | |
675 | ||
676 | The Pod format is not necessarily sufficient for writing a book. Pod | |
677 | is just meant to be an idiot-proof common source for nroff, HTML, | |
678 | TeX, and other markup languages, as used for online | |
679 | documentation. Translators exist for B<pod2text>, B<pod2html>, | |
680 | B<pod2man> (that's for nroff(1) and troff(1)), B<pod2latex>, and | |
681 | B<pod2fm>. Various others are available in CPAN. | |
682 | ||
a0d0e21e | 683 | |
b74bceb9 | 684 | =head2 Embedding Pods in Perl Modules |
d74e8afc | 685 | X<POD, embedding> |
4633a7c4 | 686 | |
13d0d101 JK |
687 | You can embed Pod documentation in your Perl modules and scripts. Start |
688 | your documentation with an empty line, a "=head1" command at the | |
689 | beginning, and end it with a "=cut" command and an empty line. The | |
690 | B<perl> executable will ignore the Pod text. You can place a Pod | |
691 | statement where B<perl> expects the beginning of a new statement, but | |
692 | not within a statement, as that would result in an error. See any of | |
693 | the supplied library modules for examples. | |
694 | ||
695 | If you're going to put your Pod at the end of the file, and you're using | |
696 | an C<__END__> or C<__DATA__> cut mark, make sure to put an empty line there | |
697 | before the first Pod command. | |
cb1a09d0 | 698 | |
8a93676d | 699 | __END__ |
cb1a09d0 | 700 | |
8a93676d | 701 | =head1 NAME |
cb1a09d0 | 702 | |
8a93676d | 703 | Time::Local - efficiently compute time from local and GMT time |
cb1a09d0 | 704 | |
8a93676d SB |
705 | Without that empty line before the "=head1", many translators wouldn't |
706 | have recognized the "=head1" as starting a Pod block. | |
cb1a09d0 | 707 | |
8a93676d | 708 | =head2 Hints for Writing Pod |
1294c5d8 | 709 | |
8a93676d | 710 | =over |
1294c5d8 JM |
711 | |
712 | =item * | |
d74e8afc | 713 | X<podchecker> X<POD, validating> |
1294c5d8 | 714 | |
8a93676d SB |
715 | The B<podchecker> command is provided for checking Pod syntax for errors |
716 | and warnings. For example, it checks for completely blank lines in | |
717 | Pod blocks and for unknown commands and formatting codes. You should | |
718 | still also pass your document through one or more translators and proofread | |
719 | the result, or print out the result and proofread that. Some of the | |
720 | problems found may be bugs in the translators, which you may or may not | |
721 | wish to work around. | |
1294c5d8 JM |
722 | |
723 | =item * | |
724 | ||
8a93676d | 725 | If you're more familiar with writing in HTML than with writing in Pod, you |
210b36aa | 726 | can try your hand at writing documentation in simple HTML, and converting |
8a93676d SB |
727 | it to Pod with the experimental L<Pod::HTML2Pod|Pod::HTML2Pod> module, |
728 | (available in CPAN), and looking at the resulting code. The experimental | |
729 | L<Pod::PXML|Pod::PXML> module in CPAN might also be useful. | |
730 | ||
731 | =item * | |
732 | ||
733 | Many older Pod translators require the lines before every Pod | |
734 | command and after every Pod command (including "=cut"!) to be a blank | |
735 | line. Having something like this: | |
736 | ||
737 | # - - - - - - - - - - - - | |
738 | =item $firecracker->boom() | |
210b36aa | 739 | |
8a93676d SB |
740 | This noisily detonates the firecracker object. |
741 | =cut | |
742 | sub boom { | |
743 | ... | |
744 | ||
745 | ...will make such Pod translators completely fail to see the Pod block | |
746 | at all. | |
747 | ||
748 | Instead, have it like this: | |
749 | ||
750 | # - - - - - - - - - - - - | |
210b36aa | 751 | |
8a93676d | 752 | =item $firecracker->boom() |
210b36aa | 753 | |
8a93676d | 754 | This noisily detonates the firecracker object. |
210b36aa | 755 | |
8a93676d | 756 | =cut |
210b36aa | 757 | |
8a93676d SB |
758 | sub boom { |
759 | ... | |
760 | ||
761 | =item * | |
762 | ||
763 | Some older Pod translators require paragraphs (including command | |
764 | paragraphs like "=head2 Functions") to be separated by I<completely> | |
765 | empty lines. If you have an apparently empty line with some spaces | |
766 | on it, this might not count as a separator for those translators, and | |
767 | that could cause odd formatting. | |
768 | ||
769 | =item * | |
1294c5d8 | 770 | |
8a93676d SB |
771 | Older translators might add wording around an LE<lt>E<gt> link, so that |
772 | C<LE<lt>Foo::BarE<gt>> may become "the Foo::Bar manpage", for example. | |
773 | So you shouldn't write things like C<the LE<lt>fooE<gt> | |
ac036724 | 774 | documentation>, if you want the translated document to read sensibly. |
775 | Instead, write C<the LE<lt>Foo::Bar|Foo::BarE<gt> documentation> or | |
8a93676d SB |
776 | C<LE<lt>the Foo::Bar documentation|Foo::BarE<gt>>, to control how the |
777 | link comes out. | |
b74bceb9 | 778 | |
1294c5d8 JM |
779 | =item * |
780 | ||
8a93676d SB |
781 | Going past the 70th column in a verbatim block might be ungracefully |
782 | wrapped by some formatters. | |
1294c5d8 JM |
783 | |
784 | =back | |
785 | ||
cb1a09d0 AD |
786 | =head1 SEE ALSO |
787 | ||
8a93676d SB |
788 | L<perlpodspec>, L<perlsyn/"PODs: Embedded Documentation">, |
789 | L<perlnewmod>, L<perldoc>, L<pod2html>, L<pod2man>, L<podchecker>. | |
4633a7c4 | 790 | |
cb1a09d0 | 791 | =head1 AUTHOR |
a0d0e21e | 792 | |
8a93676d | 793 | Larry Wall, Sean M. Burke |
a0d0e21e | 794 | |
8a93676d | 795 | =cut |