290 lines
8.2 KiB
Plaintext
290 lines
8.2 KiB
Plaintext
=head1 NAME
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perlpod - plain old documentation
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=head1 DESCRIPTION
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A pod-to-whatever translator reads a pod file paragraph by paragraph,
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and translates it to the appropriate output format. There are
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three kinds of paragraphs:
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L<verbatim|/"Verbatim Paragraph">,
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L<command|/"Command Paragraph">, and
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L<ordinary text|/"Ordinary Block of Text">.
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=head2 Verbatim Paragraph
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A verbatim paragraph, distinguished by being indented (that is,
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it starts with space or tab). It should be reproduced exactly,
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with tabs assumed to be on 8-column boundaries. There are no
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special formatting escapes, so you can't italicize or anything
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like that. A \ means \, and nothing else.
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=head2 Command Paragraph
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All command paragraphs start with "=", followed by an
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identifier, followed by arbitrary text that the command can
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use however it pleases. Currently recognized commands are
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=head1 heading
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=head2 heading
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=item text
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=over N
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=back
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=cut
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=pod
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=for X
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=begin X
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=end X
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=over 4
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=item =pod
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=item =cut
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The "=pod" directive does nothing beyond telling the compiler to lay
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off parsing code through the next "=cut". It's useful for adding
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another paragraph to the doc if you're mixing up code and pod a lot.
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=item =head1
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=item =head2
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Head1 and head2 produce first and second level headings, with the text in
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the same paragraph as the "=headn" directive forming the heading description.
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=item =over
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=item =back
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=item =item
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Item, over, and back require a little more explanation: "=over" starts a
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section specifically for the generation of a list using "=item" commands. At
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the end of your list, use "=back" to end it. You will probably want to give
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"4" as the number to "=over", as some formatters will use this for indentation.
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This should probably be a default. Note also that there are some basic rules
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to using =item: don't use them outside of an =over/=back block, use at least
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one inside an =over/=back block, you don't _have_ to include the =back if
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the list just runs off the document, and perhaps most importantly, keep the
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items consistent: either use "=item *" for all of them, to produce bullets,
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or use "=item 1.", "=item 2.", etc., to produce numbered lists, or use
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"=item foo", "=item bar", etc., i.e., things that looks nothing like bullets
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or numbers. If you start with bullets or numbers, stick with them, as many
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formatters use the first "=item" type to decide how to format the list.
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=item =for
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=item =begin
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=item =end
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For, begin, and end let you include sections that are not interpreted
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as pod text, but passed directly to particular formatters. A formatter
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that can utilize that format will use the section, otherwise it will be
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completely ignored. The directive "=for" specifies that the entire next
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paragraph is in the format indicated by the first word after
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"=for", like this:
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=for html <br>
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<p> This is a raw HTML paragraph </p>
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The paired commands "=begin" and "=end" work very similarly to "=for", but
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instead of only accepting a single paragraph, all text from "=begin" to a
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paragraph with a matching "=end" are treated as a particular format.
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Here are some examples of how to use these:
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=begin html
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<br>Figure 1.<IMG SRC="figure1.png"><br>
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=end html
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=begin text
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---------------
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| foo |
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| bar |
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---------------
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^^^^ Figure 1. ^^^^
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=end text
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Some format names that formatters currently are known to accept include
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"roff", "man", "latex", "tex", "text", and "html". (Some formatters will
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treat some of these as synonyms.)
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And don't forget, when using any command, that the command lasts up until
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the end of the B<paragraph>, not the line. Hence in the examples below, you
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can see the empty lines after each command to end its paragraph.
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Some examples of lists include:
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=over 4
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=item *
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First item
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=item *
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Second item
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=back
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=over 4
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=item Foo()
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Description of Foo function
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=item Bar()
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Description of Bar function
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=back
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=back
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=head2 Ordinary Block of Text
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It will be filled, and maybe even
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justified. Certain interior sequences are recognized both
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here and in commands:
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I<text> italicize text, used for emphasis or variables
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B<text> embolden text, used for switches and programs
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S<text> text contains non-breaking spaces
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C<code> literal code
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L<name> A link (cross reference) to name
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L<name> manual page
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L<name/ident> item in manual page
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L<name/"sec"> section in other manual page
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L<"sec"> section in this manual page
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(the quotes are optional)
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L</"sec"> ditto
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same as above but only 'text' is used for output.
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(Text can not contain the characters '/' and '|',
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and should contain matched '<' or '>')
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L<text|name>
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L<text|name/ident>
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L<text|name/"sec">
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L<text|"sec">
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L<text|/"sec">
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F<file> Used for filenames
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X<index> An index entry
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Z<> A zero-width character
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E<escape> A named character (very similar to HTML escapes)
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E<lt> A literal <
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E<gt> A literal >
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E<sol> A literal /
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E<verbar> A literal |
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(these are optional except in other interior
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sequences and when preceded by a capital letter)
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E<n> Character number n (probably in ASCII)
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E<html> Some non-numeric HTML entity, such
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as E<Agrave>
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=head2 The Intent
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That's it. The intent is simplicity, not power. I wanted paragraphs
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to look like paragraphs (block format), so that they stand out
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visually, and so that I could run them through fmt easily to reformat
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them (that's F7 in my version of B<vi>). I wanted the translator (and not
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me) to worry about whether " or ' is a left quote or a right quote
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within filled text, and I wanted it to leave the quotes alone, dammit, in
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verbatim mode, so I could slurp in a working program, shift it over 4
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spaces, and have it print out, er, verbatim. And presumably in a
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constant width font.
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In particular, you can leave things like this verbatim in your text:
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Perl
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FILEHANDLE
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$variable
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function()
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manpage(3r)
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Doubtless a few other commands or sequences will need to be added along
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the way, but I've gotten along surprisingly well with just these.
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Note that I'm not at all claiming this to be sufficient for producing a
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book. I'm just trying to make an idiot-proof common source for nroff,
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TeX, and other markup languages, as used for online documentation.
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Translators exist for B<pod2man> (that's for nroff(1) and troff(1)),
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B<pod2text>, B<pod2html>, B<pod2latex>, and B<pod2fm>.
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=head2 Embedding Pods in Perl Modules
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You can embed pod documentation in your Perl scripts. Start your
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documentation with a "=head1" command at the beginning, and end it
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with a "=cut" command. Perl will ignore the pod text. See any of the
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supplied library modules for examples. If you're going to put your
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pods at the end of the file, and you're using an __END__ or __DATA__
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cut mark, make sure to put an empty line there before the first pod
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directive.
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__END__
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=head1 NAME
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modern - I am a modern module
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If you had not had that empty line there, then the translators wouldn't
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have seen it.
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=head2 Common Pod Pitfalls
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=over 4
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=item *
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Pod translators usually will require paragraphs to be separated by
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completely empty lines. If you have an apparently empty line with
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some spaces on it, this can cause odd formatting.
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=item *
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Translators will mostly add wording around a LE<lt>E<gt> link, so that
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C<LE<lt>foo(1)E<gt>> becomes "the I<foo>(1) manpage", for example (see
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B<pod2man> for details). Thus, you shouldn't write things like C<the
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LE<lt>fooE<gt> manpage>, if you want the translated document to read
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sensibly.
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If you don need or want total control of the text used for a
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link in the output use the form LE<lt>show this text|fooE<gt>
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instead.
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=item *
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The script F<pod/checkpods.PL> in the Perl source distribution
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provides skeletal checking for lines that look empty but aren't
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B<only>, but is there as a placeholder until someone writes
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Pod::Checker. The best way to check your pod is to pass it through
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one or more translators and proofread the result, or print out the
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result and proofread that. Some of the problems found may be bugs in
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the translators, which you may or may not wish to work around.
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=back
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=head1 SEE ALSO
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L<pod2man> and L<perlsyn/"PODs: Embedded Documentation">
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=head1 AUTHOR
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Larry Wall
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