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PERLPOD(1)
NAME
perlpod - plain old documentation
DESCRIPTION
A pod-to-whatever translator reads a pod file paragraph by paragraph, and
translates it to the appropriate output format. There are three kinds of
paragraphs: verbatim, command, and ordinary text.
Verbatim Paragraph
A verbatim paragraph, distinguished by being indented (that is, it starts
with space or tab). It should be reproduced exactly, with tabs assumed to
be on 8-column boundaries. There are no special formatting escapes, so you
can't italicize or anything like that. A \ means \, and nothing else.
Command Paragraph
All command paragraphs start with "=", followed by an identifier, followed
by arbitrary text that the command can use however it pleases. Currently
recognized commands are
=head1 heading
=head2 heading
=item text
=over N
=back
=cut
=pod
=for X
=begin X
=end X
=pod
=cut
The "=pod" directive does nothing beyond telling the compiler to lay
off parsing code through the next "=cut". It's useful for adding
another paragraph to the doc if you're mixing up code and pod a lot.
=head1
=head2
Head1 and head2 produce first and second level headings, with the text
in the same paragraph as the "=headn" directive forming the heading
description.
=over
=back
=item
Item, over, and back require a little more explanation: "=over" starts
a section specifically for the generation of a list using "=item"
commands. At the end of your list, use "=back" to end it. You will
probably want to give "4" as the number to "=over", as some formatters
will use this for indentation. The unit of indentation is optional. If
the unit is not given the natural indentation of the formatting system
applied will be used. Note also that there are some basic rules to
using =item: don't use them outside of an =over/=back block, use at
least one inside an =over/=back block, you don't _have_ to include the
=back if the list just runs off the document, and perhaps most
importantly, keep the items consistent: either use "=item *" for all of
them, to produce bullets, or use "=item 1.", "=item 2.", etc., to
produce numbered lists, or use "=item foo", "=item bar", etc., i.e.,
things that looks nothing like bullets or numbers. If you start with
bullets or numbers, stick with them, as many formatters use the first
"=item" type to decide how to format the list.
=for
=begin
=end
For, begin, and end let you include sections that are not interpreted
as pod text, but passed directly to particular formatters. A formatter
that can utilize that format will use the section, otherwise it will be
completely ignored. The directive "=for" specifies that the entire
next paragraph is in the format indicated by the first word after
"=for", like this:
=for html <br>
<p> This is a raw HTML paragraph </p>
The paired commands "=begin" and "=end" work very similarly to "=for",
but instead of only accepting a single paragraph, all text from
"=begin" to a paragraph with a matching "=end" are treated as a
particular format.
Here are some examples of how to use these:
=begin html
<br>Figure 1.<IMG SRC="figure1.png"><br>
=end html
=begin text
---------------
| foo |
| bar |
---------------
^^^^ Figure 1. ^^^^
=end text
Some format names that formatters currently are known to accept include
"roff", "man", "latex", "tex", "text", and "html". (Some formatters
will treat some of these as synonyms.)
And don't forget, when using any command, that the command lasts up
until the end of the paragraph, not the line. Hence in the examples
below, you can see the empty lines after each command to end its
paragraph.
Some examples of lists include:
=over 4
=item *
First item
=item *
Second item
=back
=over 4
=item Foo()
Description of Foo function
=item Bar()
Description of Bar function
=back
Ordinary Block of Text
It will be filled, and maybe even justified. Certain interior sequences
are recognized both here and in commands:
I<text> Italicize text, used for emphasis or variables
B<text> Embolden text, used for switches and programs
S<text> Text contains non-breaking spaces
C<code> Render code in a typewriter font, or give some other
indication that this represents program text
L<name> A link (cross reference) to name
L<name> manual page
L<name/ident> item in manual page
L<name/"sec"> section in other manual page
L<"sec"> section in this manual page
(the quotes are optional)
L</"sec"> ditto
same as above but only 'text' is used for output.
(Text can not contain the characters '/' and '|',
and should contain matched '<' or '>')
L<text|name>
L<text|name/ident>
L<text|name/"sec">
L<text|"sec">
L<text|/"sec">
F<file> Used for filenames
X<index> An index entry
Z<> A zero-width character
E<escape> A named character (very similar to HTML escapes)
E<lt> A literal <
E<gt> A literal >
E<sol> A literal /
E<verbar> A literal |
(these are optional except in other interior
sequences and when preceded by a capital letter)
E<n> Character number n (probably in ASCII)
E<html> Some non-numeric HTML entity, such
as E<Agrave>
Most of the time, you will only need a single set of angle brackets to
delimit the beginning and end of interior sequences. However, sometimes
you will want to put a right angle bracket (or greater-than sign '>')
inside of a sequence. This is particularly common when using a sequence to
provide a different font-type for a snippet of code. As with all things in
Perl, there is more than one way to do it. One way is to simply escape the
closing bracket using an "E" sequence:
C<$a E<lt>=E<gt> $b>
This will produce: ""$a <=> $b""
A more readable, and perhaps more "plain" way is to use an alternate set of
delimiters that doesn't require a ">" to be escaped. As of perl5.5.660,
doubled angle brackets ("<<" and ">>") may be used if and only if there is
whitespace immediately following the opening delimiter and immediately
preceding the closing delimiter! For example, the following will do the
trick:
C<< $a <=> $b >>
In fact, you can use as many repeated angle-brackets as you like so long as
you have the same number of them in the opening and closing delimiters, and
make sure that whitespace immediately follows the last '<' of the opening
delimiter, and immediately precedes the first '>' of the closing delimiter.
So the following will also work:
C<<< $a <=> $b >>>
C<<<< $a <=> $b >>>>
This is currently supported by pod2text (Pod::Text), pod2man (Pod::Man),
and any other pod2xxx and Pod::Xxxx translator that uses Pod::Parser 1.093
or later.
The Intent
That's it. The intent is simplicity, not power. I wanted paragraphs to
look like paragraphs (block format), so that they stand out visually, and
so that I could run them through fmt easily to reformat them (that's F7 in
my version of vi). I wanted the translator (and not me) to worry about
whether " or ' is a left quote or a right quote within filled text, and I
wanted it to leave the quotes alone, dammit, in verbatim mode, so I could
slurp in a working program, shift it over 4 spaces, and have it print out,
er, verbatim. And presumably in a constant width font.
In particular, you can leave things like this verbatim in your text:
Perl
FILEHANDLE
$variable
function()
manpage(3r)
Doubtless a few other commands or sequences will need to be added along the
way, but I've gotten along surprisingly well with just these.
Note that I'm not at all claiming this to be sufficient for producing a
book. I'm just trying to make an idiot-proof common source for nroff, TeX,
and other markup languages, as used for online documentation. Translators
exist for pod2man (that's for nroff(1) and troff(1)), pod2text, pod2html,
pod2latex, and pod2fm.
Embedding Pods in Perl Modules
You can embed pod documentation in your Perl scripts. Start your
documentation with a "=head1" command at the beginning, and end it with a
"=cut" command. Perl will ignore the pod text. See any of the supplied
library modules for examples. If you're going to put your pods at the end
of the file, and you're using an __END__ or __DATA__ cut mark, make sure to
put an empty line there before the first pod directive.
__END__
=head1 NAME
modern - I am a modern module
If you had not had that empty line there, then the translators wouldn't
have seen it.
Common Pod Pitfalls
· Pod translators usually will require paragraphs to be separated by
completely empty lines. If you have an apparently empty line with some
spaces on it, this can cause odd formatting.
· Translators will mostly add wording around a L<> link, so that
"L<foo(1)>" becomes "the foo(1) manpage", for example (see pod2man for
details). Thus, you shouldn't write things like "the L<foo> manpage",
if you want the translated document to read sensibly.
If you need total control of the text used for a link in the output use
the form L<show this text|foo> instead.
· The podchecker command is provided to check pod syntax for errors and
warnings. For example, it checks for completely blank lines in pod
segments and for unknown escape sequences. It is still advised to pass
it through one or more translators and proofread the result, or print
out the result and proofread that. Some of the problems found may be
bugs in the translators, which you may or may not wish to work around.
SEE ALSO
the pod2man manpage, the PODs: Embedded Documentation entry in the perlsyn
manpage, the podchecker manpage
AUTHOR
Larry Wall
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Index for
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Alphabetical
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Top of
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