I'm assuming you mean that you have a list of error codes and want this list to be included in the running source code for the program (as a hash or array or whatever), and also in the program's documentation, but without duplicating the list of error codes.

There are three real options...

1. Define your messages in your pod, and then make your module parse its own documentation at run-time to extract those messages.

2. Define your messages in your code, and then generate your documentation from that at install time, using something like Pod Weaver.

3. Perl and Pod are two different syntaxes. It is possible (usually using heredocs) to write text which can be executed as Perl and is also seen as Pod. Here's an example:

   use 5.010;
   use strict;
   use warnings;
   
   use Data::Dumper;
   
   our %messages = map /^\s+(.+?):(.+)$/?($1=>$2):(), split "\n", <<'=cut
   +';
   =head1 MESSAGES
   
   The following messages are defined...
   
       eof:Unexpected end of file
       bad_tag:Syntax error in tag
   
   =cut
   
   print Dumper \%messages;
   [download]

   View that file with perldoc and you'll see the list of messages. Execute it, and you'll see they get dumped.

This is exactly the idea I was looking for. Thanks!

Well, if you want to stick with perl, and don't want to duplicate the data, two ways

__DATA__

=head1 ERROR MESSAGES

=item * eof

Unexpected end of file

=cut
[download]

Then when you're reading from *DATA, adjust your regex

Or better idea, make it what it is, a hash

$ podchecker junk
junk pod syntax OK.

$ perldoc junk
ERROR MESSAGES
        %E2S = (
            eof => 'Unexpected end of file',
        );


$ perl -Mstrict -Mwarnings junk
{ eof => "Unexpected end of file" }

$ cat junk

BEGIN {
   use vars qw' %E2S ';
   my $pod = <<'=head1 ERROR MESSAGES';

=head1 ERROR MESSAGES


    %E2S = (
        eof => 'Unexpected end of file',
    );


=for no_pod_formatter

=cut

}

use Data::Dump; dd\%E2S;

$
[download]

and even better idea is to use gettext, and generate the pod from your .po/.mo database, using whatever means,
a utils/gettexttopod.PL (or utils/gettexttopod ) you wrote, or whatever

Everything after __DATA__ is considered data.

package FOO::Messages;

sub foo{}

=head1 __DATA__

This is the data stuff here.

=cut

1;
__DATA__

data stuff here.
[download]

So you want to duplicate the data?

Well you cant Interpolate Perl variables in POD

Don't_repeat_yourself

In software engineering, Don't Repeat Yourself (DRY) is a principle of software development aimed at reducing repetition of information of all kinds!

I guess you wanted to include your error codes into your perl module's POD document, So go through this link to get an idea.