3 perlpod - plain old documentation
7 A pod-to-whatever translator reads a pod file paragraph by paragraph,
8 and translates it to the appropriate output format. There are
9 three kinds of paragraphs:
10 L<verbatim|/"Verbatim Paragraph">,
11 L<command|/"Command Paragraph">, and
12 L<ordinary text|/"Ordinary Block of Text">.
14 =head2 Verbatim Paragraph
16 A verbatim paragraph, distinguished by being indented (that is,
17 it starts with space or tab). It should be reproduced exactly,
18 with tabs assumed to be on 8-column boundaries. There are no
19 special formatting escapes, so you can't italicize or anything
20 like that. A \ means \, and nothing else.
22 =head2 Command Paragraph
24 All command paragraphs start with "=", followed by an
25 identifier, followed by arbitrary text that the command can
26 use however it pleases. Currently recognized commands are
45 The "=pod" directive does nothing beyond telling the compiler to lay
46 off parsing code through the next "=cut". It's useful for adding
47 another paragraph to the doc if you're mixing up code and pod a lot.
53 Head1 and head2 produce first and second level headings, with the text in
54 the same paragraph as the "=headn" directive forming the heading description.
62 Item, over, and back require a little more explanation: "=over" starts a
63 section specifically for the generation of a list using "=item" commands. At
64 the end of your list, use "=back" to end it. You will probably want to give
65 "4" as the number to "=over", as some formatters will use this for indentation.
66 This should probably be a default. Note also that there are some basic rules
67 to using =item: don't use them outside of an =over/=back block, use at least
68 one inside an =over/=back block, you don't _have_ to include the =back if
69 the list just runs off the document, and perhaps most importantly, keep the
70 items consistent: either use "=item *" for all of them, to produce bullets,
71 or use "=item 1.", "=item 2.", etc., to produce numbered lists, or use
72 "=item foo", "=item bar", etc., i.e., things that looks nothing like bullets
73 or numbers. If you start with bullets or numbers, stick with them, as many
74 formatters use the first "=item" type to decide how to format the list.
82 For, begin, and end let you include sections that are not interpreted
83 as pod text, but passed directly to particular formatters. A formatter
84 that can utilize that format will use the section, otherwise it will be
85 completely ignored. The directive "=for" specifies that the entire next
86 paragraph is in the format indicated by the first word after
90 <p> This is a raw HTML paragraph </p>
92 The paired commands "=begin" and "=end" work very similarly to "=for", but
93 instead of only accepting a single paragraph, all text from "=begin" to a
94 paragraph with a matching "=end" are treated as a particular format.
96 Here are some examples of how to use these:
100 <br>Figure 1.<IMG SRC="figure1.png"><br>
115 Some format names that formatters currently are known to accept include
116 "roff", "man", "latex", "tex", "text", and "html". (Some formatters will
117 treat some of these as synonyms.)
119 And don't forget, when using any command, that the command lasts up until
120 the end of the B<paragraph>, not the line. Hence in the examples below, you
121 can see the empty lines after each command to end its paragraph.
123 Some examples of lists include:
141 Description of Foo function
145 Description of Bar function
151 =head2 Ordinary Block of Text
153 It will be filled, and maybe even
154 justified. Certain interior sequences are recognized both
155 here and in commands:
157 I<text> Italicize text, used for emphasis or variables
158 B<text> Embolden text, used for switches and programs
159 S<text> Text contains non-breaking spaces
160 C<code> Render code in a typewriter font, or give some other
161 indication that this represents program text
162 L<name> A link (cross reference) to name
164 L<name/ident> item in manual page
165 L<name/"sec"> section in other manual page
166 L<"sec"> section in this manual page
167 (the quotes are optional)
169 same as above but only 'text' is used for output.
170 (Text can not contain the characters '/' and '|',
171 and should contain matched '<' or '>')
178 F<file> Used for filenames
179 X<index> An index entry
180 Z<> A zero-width character
181 E<escape> A named character (very similar to HTML escapes)
185 E<verbar> A literal |
186 (these are optional except in other interior
187 sequences and when preceded by a capital letter)
188 E<n> Character number n (probably in ASCII)
189 E<html> Some non-numeric HTML entity, such
192 Most of the time, you will only need a single set of angle brackets to
193 delimit the beginning and end of interior sequences. However, sometimes
194 you will want to put a right angle bracket (or greater-than sign '>')
195 inside of a sequence. This is particularly common when using a sequence
196 to provide a different font-type for a snippet of code. As with all
197 things in Perl, there is more than one way to do it. One way is to
198 simply escape the closing bracket using an C<E> sequence:
202 This will produce: "C<$a E<lt>=E<gt> $b>"
204 A more readable, and perhaps more "plain" way is to use an alternate set of
205 delimiters that doesn't require a ">" to be escaped. As of perl5.5.660,
206 doubled angle brackets ("<<" and ">>") may be used I<if and only if there
207 is whitespace immediately following the opening delimiter and immediately
208 preceding the closing delimiter!> For example, the following will do the
213 In fact, you can use as many repeated angle-brackets as you like so
214 long as you have the same number of them in the opening and closing
215 delimiters, and make sure that whitespace immediately follows the last
216 '<' of the opening delimiter, and immediately precedes the first '>' of
217 the closing delimiter. So the following will also work:
222 This is currently supported by pod2text (Pod::Text), pod2man (Pod::Man),
223 and any other pod2xxx and Pod::Xxxx translator that uses Pod::Parser
229 That's it. The intent is simplicity, not power. I wanted paragraphs
230 to look like paragraphs (block format), so that they stand out
231 visually, and so that I could run them through fmt easily to reformat
232 them (that's F7 in my version of B<vi>). I wanted the translator (and not
233 me) to worry about whether " or ' is a left quote or a right quote
234 within filled text, and I wanted it to leave the quotes alone, dammit, in
235 verbatim mode, so I could slurp in a working program, shift it over 4
236 spaces, and have it print out, er, verbatim. And presumably in a
239 In particular, you can leave things like this verbatim in your text:
247 Doubtless a few other commands or sequences will need to be added along
248 the way, but I've gotten along surprisingly well with just these.
250 Note that I'm not at all claiming this to be sufficient for producing a
251 book. I'm just trying to make an idiot-proof common source for nroff,
252 TeX, and other markup languages, as used for online documentation.
253 Translators exist for B<pod2man> (that's for nroff(1) and troff(1)),
254 B<pod2text>, B<pod2html>, B<pod2latex>, and B<pod2fm>.
256 =head2 Embedding Pods in Perl Modules
258 You can embed pod documentation in your Perl scripts. Start your
259 documentation with a "=head1" command at the beginning, and end it
260 with a "=cut" command. Perl will ignore the pod text. See any of the
261 supplied library modules for examples. If you're going to put your
262 pods at the end of the file, and you're using an __END__ or __DATA__
263 cut mark, make sure to put an empty line there before the first pod
270 modern - I am a modern module
272 If you had not had that empty line there, then the translators wouldn't
275 =head2 Common Pod Pitfalls
281 Pod translators usually will require paragraphs to be separated by
282 completely empty lines. If you have an apparently empty line with
283 some spaces on it, this can cause odd formatting.
287 Translators will mostly add wording around a LE<lt>E<gt> link, so that
288 C<LE<lt>foo(1)E<gt>> becomes "the I<foo>(1) manpage", for example (see
289 B<pod2man> for details). Thus, you shouldn't write things like C<the
290 LE<lt>fooE<gt> manpage>, if you want the translated document to read
293 If you need total control of the text used for a link in the output
294 use the form LE<lt>show this text|fooE<gt> instead.
298 The B<podchecker> command is provided to check pod syntax
299 for errors and warnings. For example, it checks for completely
300 blank lines in pod segments and for unknown escape sequences.
301 It is still advised to pass it through
302 one or more translators and proofread the result, or print out the
303 result and proofread that. Some of the problems found may be bugs in
304 the translators, which you may or may not wish to work around.
310 L<pod2man>, L<perlsyn/"PODs: Embedded Documentation">,