


PERLPOD(1)       Perl Programmers Reference Guide      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 head-
           ings, with the text in the same paragraph as the
           "=headn" directive forming the heading description.

       =over
       =back





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PERLPOD(1)       Perl Programmers Reference Guide      PERLPOD(1)


       =item
           Item, over, and back require a little more explana-
           tion: "=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 per-
           haps most importantly, keep the items consistent:
           either use "=item *" for all of them, to produce bul-
           lets, 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 num-
           bers. 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 indi-
           cated 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 sim-
           ilarly to "=for", but instead of only accepting a sin-
           gle 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





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PERLPOD(1)       Perl Programmers Reference Guide      PERLPOD(1)


              ---------------
              |  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 com-
       mands:






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           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



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PERLPOD(1)       Perl Programmers Reference Guide      PERLPOD(1)


       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 ver-
       sion 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 lan-
       guages, as used for online documentation.  Translators
       exist for pod2man  (that's for nroff(1) and troff(1)),
       pod2text, pod2html, pod2latex, and pod2fm.





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PERLPOD(1)       Perl Programmers Reference Guide      PERLPOD(1)


       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 mod-
       ules 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 trans-
       lators wouldn't have seen it.

       Common Pod Pitfalls


       o   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.

       o   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.

       o   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 transla-
           tors, 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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