| 1 | |
| 2 | =for comment |
| 3 | This document is in Pod format. To read this, use a Pod formatter, |
| 4 | like "perldoc perlpod". |
| 5 | |
| 6 | =head1 NAME |
| 7 | |
| 8 | perlpod - the Plain Old Documentation format |
| 9 | |
| 10 | =head1 DESCRIPTION |
| 11 | |
| 12 | Pod is a simple-to-use markup language used for writing documentation |
| 13 | for Perl, Perl programs, and Perl modules. |
| 14 | |
| 15 | Translators are available for converting Pod to various formats |
| 16 | like plain text, HTML, man pages, and more. |
| 17 | |
| 18 | Pod markup consists of three basic kinds of paragraphs: |
| 19 | L<ordinary|/"Ordinary Paragraph">, |
| 20 | L<verbatim|/"Verbatim Paragraph">, and |
| 21 | L<command|/"Command Paragraph">. |
| 22 | |
| 23 | |
| 24 | =head2 Ordinary Paragraph |
| 25 | |
| 26 | Most paragraphs in your documentation will be ordinary blocks |
| 27 | of text, like this one. You can simply type in your text without |
| 28 | any markup whatsoever, and with just a blank line before and |
| 29 | after. When it gets formatted, it will undergo minimal formatting, |
| 30 | like being rewrapped, probably put into a proportionally spaced |
| 31 | font, and maybe even justified. |
| 32 | |
| 33 | You can use formatting codes in ordinary paragraphs, for B<bold>, |
| 34 | I<italic>, C<code-style>, L<hyperlinks|perlfaq>, and more. Such |
| 35 | codes are explained in the "L<Formatting Codes|/"Formatting Codes">" |
| 36 | section, below. |
| 37 | |
| 38 | |
| 39 | =head2 Verbatim Paragraph |
| 40 | |
| 41 | Verbatim paragraphs are usually used for presenting a codeblock or |
| 42 | other text which does not require any special parsing or formatting, |
| 43 | and which shouldn't be wrapped. |
| 44 | |
| 45 | A verbatim paragraph is distinguished by having its first character |
| 46 | be a space or a tab. (And commonly, all its lines begin with spaces |
| 47 | and/or tabs.) It should be reproduced exactly, with tabs assumed to |
| 48 | be on 8-column boundaries. There are no special formatting codes, |
| 49 | so you can't italicize or anything like that. A \ means \, and |
| 50 | nothing else. |
| 51 | |
| 52 | |
| 53 | =head2 Command Paragraph |
| 54 | |
| 55 | A command paragraph is used for special treatment of whole chunks |
| 56 | of text, usually as headings or parts of lists. |
| 57 | |
| 58 | All command paragraphs (which are typically only one line long) start |
| 59 | with "=", followed by an identifier, followed by arbitrary text that |
| 60 | the command can use however it pleases. Currently recognized commands |
| 61 | are |
| 62 | |
| 63 | =head1 Heading Text |
| 64 | =head2 Heading Text |
| 65 | =head3 Heading Text |
| 66 | =head4 Heading Text |
| 67 | =over indentlevel |
| 68 | =item stuff |
| 69 | =back |
| 70 | =cut |
| 71 | =pod |
| 72 | =begin format |
| 73 | =end format |
| 74 | =for format text... |
| 75 | |
| 76 | To explain them each in detail: |
| 77 | |
| 78 | =over |
| 79 | |
| 80 | =item C<=head1 I<Heading Text>> |
| 81 | |
| 82 | =item C<=head2 I<Heading Text>> |
| 83 | |
| 84 | =item C<=head3 I<Heading Text>> |
| 85 | |
| 86 | =item C<=head4 I<Heading Text>> |
| 87 | |
| 88 | Head1 through head4 produce headings, head1 being the highest |
| 89 | level. The text in the rest of this paragraph is the content of the |
| 90 | heading. For example: |
| 91 | |
| 92 | =head2 Object Attributes |
| 93 | |
| 94 | The text "Object Attributes" comprises the heading there. (Note that |
| 95 | head3 and head4 are recent additions, not supported in older Pod |
| 96 | translators.) The text in these heading commands can use |
| 97 | formatting codes, as seen here: |
| 98 | |
| 99 | =head2 Possible Values for C<$/> |
| 100 | |
| 101 | Such commands are explained in the |
| 102 | "L<Formatting Codes|/"Formatting Codes">" section, below. |
| 103 | |
| 104 | =item C<=over I<indentlevel>> |
| 105 | |
| 106 | =item C<=item I<stuff...>> |
| 107 | |
| 108 | =item C<=back> |
| 109 | |
| 110 | Item, over, and back require a little more explanation: "=over" starts |
| 111 | a region specifically for the generation of a list using "=item" |
| 112 | commands, or for indenting (groups of) normal paragraphs. At the end |
| 113 | of your list, use "=back" to end it. The I<indentlevel> option to |
| 114 | "=over" indicates how far over to indent, generally in ems (where |
| 115 | one em is the width of an "M" in the document's base font) or roughly |
| 116 | comparable units; if there is no I<indentlevel> option, it defaults |
| 117 | to four. (And some formatters may just ignore whatever I<indentlevel> |
| 118 | you provide.) In the I<stuff> in C<=item I<stuff...>>, you may |
| 119 | use formatting codes, as seen here: |
| 120 | |
| 121 | =item Using C<$|> to Control Buffering |
| 122 | |
| 123 | Such commands are explained in the |
| 124 | "L<Formatting Codes|/"Formatting Codes">" section, below. |
| 125 | |
| 126 | Note also that there are some basic rules to using "=over" ... |
| 127 | "=back" regions: |
| 128 | |
| 129 | =over |
| 130 | |
| 131 | =item * |
| 132 | |
| 133 | Don't use "=item"s outside of an "=over" ... "=back" region. |
| 134 | |
| 135 | =item * |
| 136 | |
| 137 | The first thing after the "=over" command should be an "=item", unless |
| 138 | there aren't going to be any items at all in this "=over" ... "=back" |
| 139 | region. |
| 140 | |
| 141 | =item * |
| 142 | |
| 143 | Don't put "=headI<n>" commands inside an "=over" ... "=back" region. |
| 144 | |
| 145 | =item * |
| 146 | |
| 147 | And perhaps most importantly, keep the items consistent: either use |
| 148 | "=item *" for all of them, to produce bullets; or use "=item 1.", |
| 149 | "=item 2.", etc., to produce numbered lists; or use "=item foo", |
| 150 | "=item bar", etc. -- namely, things that look nothing like bullets or |
| 151 | numbers. |
| 152 | |
| 153 | If you start with bullets or numbers, stick with them, as |
| 154 | formatters use the first "=item" type to decide how to format the |
| 155 | list. |
| 156 | |
| 157 | =back |
| 158 | |
| 159 | =item C<=cut> |
| 160 | |
| 161 | To end a Pod block, use a blank line, |
| 162 | then a line beginning with "=cut", and a blank |
| 163 | line after it. This lets Perl (and the Pod formatter) know that |
| 164 | this is where Perl code is resuming. (The blank line before the "=cut" |
| 165 | is not technically necessary, but many older Pod processors require it.) |
| 166 | |
| 167 | =item C<=pod> |
| 168 | |
| 169 | The "=pod" command by itself doesn't do much of anything, but it |
| 170 | signals to Perl (and Pod formatters) that a Pod block starts here. A |
| 171 | Pod block starts with I<any> command paragraph, so a "=pod" command is |
| 172 | usually used just when you want to start a Pod block with an ordinary |
| 173 | paragraph or a verbatim paragraph. For example: |
| 174 | |
| 175 | =item stuff() |
| 176 | |
| 177 | This function does stuff. |
| 178 | |
| 179 | =cut |
| 180 | |
| 181 | sub stuff { |
| 182 | ... |
| 183 | } |
| 184 | |
| 185 | =pod |
| 186 | |
| 187 | Remember to check its return value, as in: |
| 188 | |
| 189 | stuff() || die "Couldn't do stuff!"; |
| 190 | |
| 191 | =cut |
| 192 | |
| 193 | =item C<=begin I<formatname>> |
| 194 | |
| 195 | =item C<=end I<formatname>> |
| 196 | |
| 197 | =item C<=for I<formatname> I<text...>> |
| 198 | |
| 199 | For, begin, and end will let you have regions of text/code/data that |
| 200 | are not generally interpreted as normal Pod text, but are passed |
| 201 | directly to particular formatters, or are otherwise special. A |
| 202 | formatter that can use that format will use the region, otherwise it |
| 203 | will be completely ignored. |
| 204 | |
| 205 | A command "=begin I<formatname>", some paragraphs, and a |
| 206 | command "=end I<formatname>", mean that the text/data inbetween |
| 207 | is meant for formatters that understand the special format |
| 208 | called I<formatname>. For example, |
| 209 | |
| 210 | =begin html |
| 211 | |
| 212 | <hr> <img src="thang.png"> |
| 213 | <p> This is a raw HTML paragraph </p> |
| 214 | |
| 215 | =end html |
| 216 | |
| 217 | The command "=for I<formatname> I<text...>" |
| 218 | specifies that the remainder of just this paragraph (starting |
| 219 | right after I<formatname>) is in that special format. |
| 220 | |
| 221 | =for html <hr> <img src="thang.png"> |
| 222 | <p> This is a raw HTML paragraph </p> |
| 223 | |
| 224 | This means the same thing as the above "=begin html" ... "=end html" |
| 225 | region. |
| 226 | |
| 227 | That is, with "=for", you can have only one paragraph's worth |
| 228 | of text (i.e., the text in "=foo targetname text..."), but with |
| 229 | "=begin targetname" ... "=end targetname", you can have any amount |
| 230 | of stuff inbetween. (Note that there still must be a blank line |
| 231 | after the "=begin" command and a blank line before the "=end" |
| 232 | command. |
| 233 | |
| 234 | Here are some examples of how to use these: |
| 235 | |
| 236 | =begin html |
| 237 | |
| 238 | <br>Figure 1.<br><IMG SRC="figure1.png"><br> |
| 239 | |
| 240 | =end html |
| 241 | |
| 242 | =begin text |
| 243 | |
| 244 | --------------- |
| 245 | | foo | |
| 246 | | bar | |
| 247 | --------------- |
| 248 | |
| 249 | ^^^^ Figure 1. ^^^^ |
| 250 | |
| 251 | =end text |
| 252 | |
| 253 | Some format names that formatters currently are known to accept |
| 254 | include "roff", "man", "latex", "tex", "text", and "html". (Some |
| 255 | formatters will treat some of these as synonyms.) |
| 256 | |
| 257 | A format name of "comment" is common for just making notes (presumably |
| 258 | to yourself) that won't appear in any formatted version of the Pod |
| 259 | document: |
| 260 | |
| 261 | =for comment |
| 262 | Make sure that all the available options are documented! |
| 263 | |
| 264 | Some I<formatnames> will require a leading colon (as in |
| 265 | C<"=for :formatname">, or |
| 266 | C<"=begin :formatname" ... "=end :formatname">), |
| 267 | to signal that the text is not raw data, but instead I<is> Pod text |
| 268 | (i.e., possibly containing formatting codes) that's just not for |
| 269 | normal formatting (e.g., may not be a normal-use paragraph, but might |
| 270 | be for formatting as a footnote). |
| 271 | |
| 272 | =back |
| 273 | |
| 274 | And don't forget, when using any command, that the command lasts up |
| 275 | until the end of its I<paragraph>, not its line. So in the |
| 276 | examples below, you can see that every command needs the blank |
| 277 | line after it, to end its paragraph. |
| 278 | |
| 279 | Some examples of lists include: |
| 280 | |
| 281 | =over |
| 282 | |
| 283 | =item * |
| 284 | |
| 285 | First item |
| 286 | |
| 287 | =item * |
| 288 | |
| 289 | Second item |
| 290 | |
| 291 | =back |
| 292 | |
| 293 | =over |
| 294 | |
| 295 | =item Foo() |
| 296 | |
| 297 | Description of Foo function |
| 298 | |
| 299 | =item Bar() |
| 300 | |
| 301 | Description of Bar function |
| 302 | |
| 303 | =back |
| 304 | |
| 305 | |
| 306 | =head2 Formatting Codes |
| 307 | |
| 308 | In ordinary paragraphs and in some command paragraphs, various |
| 309 | formatting codes (a.k.a. "interior sequences") can be used: |
| 310 | |
| 311 | =for comment |
| 312 | "interior sequences" is such an opaque term. |
| 313 | Prefer "formatting codes" instead. |
| 314 | |
| 315 | =over |
| 316 | |
| 317 | =item C<IE<lt>textE<gt>> -- italic text |
| 318 | |
| 319 | Used for emphasis ("C<be IE<lt>careful!E<gt>>") and parameters |
| 320 | ("C<redo IE<lt>LABELE<gt>>") |
| 321 | |
| 322 | =item C<BE<lt>textE<gt>> -- bold text |
| 323 | |
| 324 | Used for switches ("C<perl's BE<lt>-nE<gt> switch>"), programs |
| 325 | ("C<some systems provide a BE<lt>chfnE<gt> for that>"), |
| 326 | emphasis ("C<be BE<lt>careful!E<gt>>"), and so on |
| 327 | ("C<and that feature is known as BE<lt>autovivificationE<gt>>"). |
| 328 | |
| 329 | =item C<CE<lt>codeE<gt>> -- code text |
| 330 | |
| 331 | Renders code in a typewriter font, or gives some other indication that |
| 332 | this represents program text ("C<CE<lt>gmtime($^T)E<gt>>") or some other |
| 333 | form of computerese ("C<CE<lt>drwxr-xr-xE<gt>>"). |
| 334 | |
| 335 | =item C<LE<lt>nameE<gt>> -- a hyperlink |
| 336 | |
| 337 | There are various syntaxes, listed below. In the syntaxes given, |
| 338 | C<text>, C<name>, and C<section> cannot contain the characters |
| 339 | '/' and '|'; and any '<' or '>' should be matched. |
| 340 | |
| 341 | =over |
| 342 | |
| 343 | =item * |
| 344 | |
| 345 | C<LE<lt>nameE<gt>> |
| 346 | |
| 347 | Link to a Perl manual page (e.g., C<LE<lt>Net::PingE<gt>>). Note |
| 348 | that C<name> should not contain spaces. This syntax |
| 349 | is also occasionally used for references to UNIX man pages, as in |
| 350 | C<LE<lt>crontab(5)E<gt>>. |
| 351 | |
| 352 | =item * |
| 353 | |
| 354 | C<LE<lt>name/"sec"E<gt>> or C<LE<lt>name/secE<gt>> |
| 355 | |
| 356 | Link to a section in other manual page. E.g., |
| 357 | C<LE<lt>perlsyn/"For Loops"E<gt>> |
| 358 | |
| 359 | =item * |
| 360 | |
| 361 | C<LE<lt>/"sec"E<gt>> or C<LE<lt>/secE<gt>> or C<LE<lt>"sec"E<gt>> |
| 362 | |
| 363 | Link to a section in this manual page. E.g., |
| 364 | C<LE<lt>/"Object Methods"E<gt>> |
| 365 | |
| 366 | =back |
| 367 | |
| 368 | A section is started by the named heading or item. For |
| 369 | example, C<LE<lt>perlvar/$.E<gt>> or C<LE<lt>perlvar/"$."E<gt>> both |
| 370 | link to the section started by "C<=item $.>" in perlvar. And |
| 371 | C<LE<lt>perlsyn/For LoopsE<gt>> or C<LE<lt>perlsyn/"For Loops"E<gt>> |
| 372 | both link to the section started by "C<=head2 For Loops>" |
| 373 | in perlsyn. |
| 374 | |
| 375 | To control what text is used for display, you |
| 376 | use "C<LE<lt>text|...E<gt>>", as in: |
| 377 | |
| 378 | =over |
| 379 | |
| 380 | =item * |
| 381 | |
| 382 | C<LE<lt>text|nameE<gt>> |
| 383 | |
| 384 | Link this text to that manual page. E.g., |
| 385 | C<LE<lt>Perl Error Messages|perldiagE<gt>> |
| 386 | |
| 387 | =item * |
| 388 | |
| 389 | C<LE<lt>text|name/"sec"E<gt>> or C<LE<lt>text|name/secE<gt>> |
| 390 | |
| 391 | Link this text to that section in that manual page. E.g., |
| 392 | C<LE<lt>SWITCH statements|perlsyn/"Basic BLOCKs and Switch |
| 393 | Statements"E<gt>> |
| 394 | |
| 395 | =item * |
| 396 | |
| 397 | C<LE<lt>text|/"sec"E<gt>> or C<LE<lt>text|/secE<gt>> |
| 398 | or C<LE<lt>text|"sec"E<gt>> |
| 399 | |
| 400 | Link this text to that section in this manual page. E.g., |
| 401 | C<LE<lt>the various attributes|/"Member Data"E<gt>> |
| 402 | |
| 403 | =back |
| 404 | |
| 405 | Or you can link to a web page: |
| 406 | |
| 407 | =over |
| 408 | |
| 409 | =item * |
| 410 | |
| 411 | C<LE<lt>scheme:...E<gt>> |
| 412 | |
| 413 | Links to an absolute URL. For example, |
| 414 | C<LE<lt>http://www.perl.org/E<gt>>. But note |
| 415 | that there is no corresponding C<LE<lt>text|scheme:...E<gt>> syntax, for |
| 416 | various reasons. |
| 417 | |
| 418 | =back |
| 419 | |
| 420 | =item C<EE<lt>escapeE<gt>> -- a character escape |
| 421 | |
| 422 | Very similar to HTML/XML C<&I<foo>;> "entity references": |
| 423 | |
| 424 | =over |
| 425 | |
| 426 | =item * |
| 427 | |
| 428 | C<EE<lt>ltE<gt>> -- a literal E<lt> (less than) |
| 429 | |
| 430 | =item * |
| 431 | |
| 432 | C<EE<lt>gtE<gt>> -- a literal E<gt> (greater than) |
| 433 | |
| 434 | =item * |
| 435 | |
| 436 | C<EE<lt>verbarE<gt>> -- a literal | (I<ver>tical I<bar>) |
| 437 | |
| 438 | =item * |
| 439 | |
| 440 | C<EE<lt>solE<gt>> = a literal / (I<sol>idus) |
| 441 | |
| 442 | The above four are optional except in other formatting codes, |
| 443 | notably C<LE<lt>...E<gt>>, and when preceded by a |
| 444 | capital letter. |
| 445 | |
| 446 | =item * |
| 447 | |
| 448 | C<EE<lt>htmlnameE<gt>> |
| 449 | |
| 450 | Some non-numeric HTML entity name, such as C<EE<lt>eacuteE<gt>>, |
| 451 | meaning the same thing as C<é> in HTML -- i.e., a lowercase |
| 452 | e with an acute (/-shaped) accent. |
| 453 | |
| 454 | =item * |
| 455 | |
| 456 | C<EE<lt>numberE<gt>> |
| 457 | |
| 458 | The ASCII/Latin-1/Unicode character with that number. A |
| 459 | leading "0x" means that I<number> is hex, as in |
| 460 | C<EE<lt>0x201EE<gt>>. A leading "0" means that I<number> is octal, |
| 461 | as in C<EE<lt>075E<gt>>. Otherwise I<number> is interpreted as being |
| 462 | in decimal, as in C<EE<lt>181E<gt>>. |
| 463 | |
| 464 | Note that older Pod formatters might not recognize octal or |
| 465 | hex numeric escapes, and that many formatters cannot reliably |
| 466 | render characters above 255. (Some formatters may even have |
| 467 | to use compromised renderings of Latin-1 characters, like |
| 468 | rendering C<EE<lt>eacuteE<gt>> as just a plain "e".) |
| 469 | |
| 470 | =back |
| 471 | |
| 472 | =item C<FE<lt>filenameE<gt>> -- used for filenames |
| 473 | |
| 474 | Typically displayed in italics. Example: "C<FE<lt>.cshrcE<gt>>" |
| 475 | |
| 476 | =item C<SE<lt>textE<gt>> -- text contains non-breaking spaces |
| 477 | |
| 478 | This means that the words in I<text> should not be broken |
| 479 | across lines. Example: S<C<SE<lt>$x ? $y : $zE<gt>>>. |
| 480 | |
| 481 | =item C<XE<lt>topic nameE<gt>> -- an index entry |
| 482 | |
| 483 | This is ignored by most formatters, but some may use it for building |
| 484 | indexes. It always renders as empty-string. |
| 485 | Example: C<XE<lt>absolutizing relative URLsE<gt>> |
| 486 | |
| 487 | =item C<ZE<lt>E<gt>> -- a null (zero-effect) formatting code |
| 488 | |
| 489 | This is rarely used. It's one way to get around using an |
| 490 | EE<lt>...E<gt> code sometimes. For example, instead of |
| 491 | "C<NEE<lt>ltE<gt>3>" (for "NE<lt>3") you could write |
| 492 | "C<NZE<lt>E<gt>E<lt>3>" (the "ZE<lt>E<gt>" breaks up the "N" and |
| 493 | the "E<lt>" so they can't be considered |
| 494 | the part of a (fictitious) "NE<lt>...E<gt>" code. |
| 495 | |
| 496 | =for comment |
| 497 | This was formerly explained as a "zero-width character". But it in |
| 498 | most parser models, it parses to nothing at all, as opposed to parsing |
| 499 | as if it were a E<zwnj> or E<zwj>, which are REAL zero-width characters. |
| 500 | So "width" and "character" are exactly the wrong words. |
| 501 | |
| 502 | =back |
| 503 | |
| 504 | Most of the time, you will need only a single set of angle brackets to |
| 505 | delimit the beginning and end of formatting codes. However, |
| 506 | sometimes you will want to put a real right angle bracket (a |
| 507 | greater-than sign, '>') inside of a formatting code. This is particularly |
| 508 | common when using a formatting code to provide a different font-type for a |
| 509 | snippet of code. As with all things in Perl, there is more than |
| 510 | one way to do it. One way is to simply escape the closing bracket |
| 511 | using an C<E> code: |
| 512 | |
| 513 | C<$a E<lt>=E<gt> $b> |
| 514 | |
| 515 | This will produce: "C<$a E<lt>=E<gt> $b>" |
| 516 | |
| 517 | A more readable, and perhaps more "plain" way is to use an alternate |
| 518 | set of delimiters that doesn't require a single ">" to be escaped. With |
| 519 | the Pod formatters that are standard starting with perl5.5.660, doubled |
| 520 | angle brackets ("<<" and ">>") may be used I<if and only if there is |
| 521 | whitespace right after the opening delimiter and whitespace right |
| 522 | before the closing delimiter!> For example, the following will |
| 523 | do the trick: |
| 524 | |
| 525 | C<< $a <=> $b >> |
| 526 | |
| 527 | In fact, you can use as many repeated angle-brackets as you like so |
| 528 | long as you have the same number of them in the opening and closing |
| 529 | delimiters, and make sure that whitespace immediately follows the last |
| 530 | '<' of the opening delimiter, and immediately precedes the first '>' |
| 531 | of the closing delimiter. (The whitespace is ignored.) So the |
| 532 | following will also work: |
| 533 | |
| 534 | C<<< $a <=> $b >>> |
| 535 | C<<<< $a <=> $b >>>> |
| 536 | |
| 537 | And they all mean exactly the same as this: |
| 538 | |
| 539 | C<$a E<lt>=E<gt> $b> |
| 540 | |
| 541 | As a further example, this means that if you wanted to put these bits of |
| 542 | code in C<C> (code) style: |
| 543 | |
| 544 | open(X, ">>thing.dat") || die $! |
| 545 | $foo->bar(); |
| 546 | |
| 547 | you could do it like so: |
| 548 | |
| 549 | C<<< open(X, ">>thing.dat") || die $! >>> |
| 550 | C<< $foo->bar(); >> |
| 551 | |
| 552 | which is presumably easier to read than the old way: |
| 553 | |
| 554 | C<open(X, "E<gt>E<gt>thing.dat") || die $!> |
| 555 | C<$foo-E<gt>bar(); >> |
| 556 | |
| 557 | This is currently supported by pod2text (Pod::Text), pod2man (Pod::Man), |
| 558 | and any other pod2xxx or Pod::Xxxx translators that use |
| 559 | Pod::Parser 1.093 or later, or Pod::Tree 1.02 or later. |
| 560 | |
| 561 | =head2 The Intent |
| 562 | |
| 563 | The intent is simplicity of use, not power of expression. Paragraphs |
| 564 | look like paragraphs (block format), so that they stand out |
| 565 | visually, and so that I could run them through C<fmt> easily to reformat |
| 566 | them (that's F7 in my version of B<vi>, or Esc Q in my version of |
| 567 | B<emacs>). I wanted the translator to always leave the C<'> and C<`> and |
| 568 | C<"> quotes alone, in verbatim mode, so I could slurp in a |
| 569 | working program, shift it over four spaces, and have it print out, er, |
| 570 | verbatim. And presumably in a monospace font. |
| 571 | |
| 572 | The Pod format is not necessarily sufficient for writing a book. Pod |
| 573 | is just meant to be an idiot-proof common source for nroff, HTML, |
| 574 | TeX, and other markup languages, as used for online |
| 575 | documentation. Translators exist for B<pod2text>, B<pod2html>, |
| 576 | B<pod2man> (that's for nroff(1) and troff(1)), B<pod2latex>, and |
| 577 | B<pod2fm>. Various others are available in CPAN. |
| 578 | |
| 579 | |
| 580 | =head2 Embedding Pods in Perl Modules |
| 581 | |
| 582 | You can embed Pod documentation in your Perl modules and scripts. |
| 583 | Start your documentation with an empty line, a "=head1" command at the |
| 584 | beginning, and end it with a "=cut" command and an empty line. Perl |
| 585 | will ignore the Pod text. See any of the supplied library modules for |
| 586 | examples. If you're going to put your Pod at the end of the file, and |
| 587 | you're using an __END__ or __DATA__ cut mark, make sure to put an |
| 588 | empty line there before the first Pod command. |
| 589 | |
| 590 | __END__ |
| 591 | |
| 592 | =head1 NAME |
| 593 | |
| 594 | Time::Local - efficiently compute time from local and GMT time |
| 595 | |
| 596 | Without that empty line before the "=head1", many translators wouldn't |
| 597 | have recognized the "=head1" as starting a Pod block. |
| 598 | |
| 599 | =head2 Hints for Writing Pod |
| 600 | |
| 601 | =over |
| 602 | |
| 603 | =item * |
| 604 | |
| 605 | The B<podchecker> command is provided for checking Pod syntax for errors |
| 606 | and warnings. For example, it checks for completely blank lines in |
| 607 | Pod blocks and for unknown commands and formatting codes. You should |
| 608 | still also pass your document through one or more translators and proofread |
| 609 | the result, or print out the result and proofread that. Some of the |
| 610 | problems found may be bugs in the translators, which you may or may not |
| 611 | wish to work around. |
| 612 | |
| 613 | =item * |
| 614 | |
| 615 | If you're more familiar with writing in HTML than with writing in Pod, you |
| 616 | can try your hand at writing documentation in simple HTML, and converting |
| 617 | it to Pod with the experimental L<Pod::HTML2Pod|Pod::HTML2Pod> module, |
| 618 | (available in CPAN), and looking at the resulting code. The experimental |
| 619 | L<Pod::PXML|Pod::PXML> module in CPAN might also be useful. |
| 620 | |
| 621 | =item * |
| 622 | |
| 623 | Many older Pod translators require the lines before every Pod |
| 624 | command and after every Pod command (including "=cut"!) to be a blank |
| 625 | line. Having something like this: |
| 626 | |
| 627 | # - - - - - - - - - - - - |
| 628 | =item $firecracker->boom() |
| 629 | |
| 630 | This noisily detonates the firecracker object. |
| 631 | =cut |
| 632 | sub boom { |
| 633 | ... |
| 634 | |
| 635 | ...will make such Pod translators completely fail to see the Pod block |
| 636 | at all. |
| 637 | |
| 638 | Instead, have it like this: |
| 639 | |
| 640 | # - - - - - - - - - - - - |
| 641 | |
| 642 | =item $firecracker->boom() |
| 643 | |
| 644 | This noisily detonates the firecracker object. |
| 645 | |
| 646 | =cut |
| 647 | |
| 648 | sub boom { |
| 649 | ... |
| 650 | |
| 651 | =item * |
| 652 | |
| 653 | Some older Pod translators require paragraphs (including command |
| 654 | paragraphs like "=head2 Functions") to be separated by I<completely> |
| 655 | empty lines. If you have an apparently empty line with some spaces |
| 656 | on it, this might not count as a separator for those translators, and |
| 657 | that could cause odd formatting. |
| 658 | |
| 659 | =item * |
| 660 | |
| 661 | Older translators might add wording around an LE<lt>E<gt> link, so that |
| 662 | C<LE<lt>Foo::BarE<gt>> may become "the Foo::Bar manpage", for example. |
| 663 | So you shouldn't write things like C<the LE<lt>fooE<gt> |
| 664 | documentation>, if you want the translated document to read sensibly |
| 665 | -- instead write C<the LE<lt>Foo::Bar|Foo::BarE<gt> documentation> or |
| 666 | C<LE<lt>the Foo::Bar documentation|Foo::BarE<gt>>, to control how the |
| 667 | link comes out. |
| 668 | |
| 669 | =item * |
| 670 | |
| 671 | Going past the 70th column in a verbatim block might be ungracefully |
| 672 | wrapped by some formatters. |
| 673 | |
| 674 | =back |
| 675 | |
| 676 | =head1 SEE ALSO |
| 677 | |
| 678 | L<perlpodspec>, L<perlsyn/"PODs: Embedded Documentation">, |
| 679 | L<perlnewmod>, L<perldoc>, L<pod2html>, L<pod2man>, L<podchecker>. |
| 680 | |
| 681 | =head1 AUTHOR |
| 682 | |
| 683 | Larry Wall, Sean M. Burke |
| 684 | |
| 685 | =cut |