The following is a sample of what I want to be able to do.

#!/usr/bin/perl
use strict;
use warnings FATAL => qw( all );

use CGI::Carp qw(fatalsToBrowser);

use lib '../files/perl/lib';
use Base::HTML qw(print_story print_definitions);

print_story(*DATA,1);

__DATA__
Paragraph that opens the document.
2 Heading for definition list
This is the paragraph that precedes the definition list.
&print_definitions( file => "some_file_a.txt", headings => ["term","de
+finition"],)
This is the paragraph that follows the definition list.
2 Heading for next definition list
This is the paragraph that precedes the next definition list.
&print_definitions( file => "some_file_b.txt", headings => ["term","de
+finition 1","definition 2"],)
This is the paragraph that follows the next definition list.
2 Heading for the close of the document
The paragraph that closes the document.
[download]

In print_story I would like to have something simple like, but I doubt it will be that simple.

elsif ($line =~ /^\&/) {
  eval($line);
}
[download]

In print_story I would like to have something simple like, but I doubt it will be that simple.

Sure, it can be that simple, though I might feel safer trying to avoid arbitrary code execution with Safe like

#!/usr/bin/perl   --
use strict; use warnings;
use Safe;

my $str = <<'__STR__';
&print_definitions( file => "some_file_a.txt", headings => ["term","de
+finition"],)
&print_definitions( file => "some_file_b.txt", headings => ["term","de
+finition 1","definition 2"],)
&f()
&f ( 1 )
&eff( 'a', "A\tB", 3  )
__STR__

my $namespace = __PACKAGE__;
my %dispatch = (
    eff => \&f,
    _default => sub {},
);
open my($in), '<', \$str;
while( my $line = <$in> ){
    if( my( $sub, $args ) = $line =~ /^\&([^\(\s]+)\s*(.*)/) {
        print "## $sub  $args \n";
        my $subref = $namespace->can( $sub );
        $subref ||= $dispatch{$sub} || $dispatch{_default};
        if( $subref ){
            $subref->(
                length $args
                ? Safe->new->reval( $args )
                : ()
            );
        }
    }
}
close $in;
sub print_definitions { print "print_definitions says [ @_ ]\n\n"; }
sub f { print "f says [ @_ ]\n\n"; }
__END__

## print_definitions  ( file => "some_file_a.txt", headings => ["term"
+,"definition"],)
print_definitions says [ file some_file_a.txt headings ARRAY(0xb0b93c)
+ ]

## print_definitions  ( file => "some_file_b.txt", headings => ["term"
+,"definition 1","definition 2"],)
print_definitions says [ file some_file_b.txt headings ARRAY(0xb0b5ec)
+ ]

## f  ()
f says [  ]

## f  ( 1 )
f says [ 1 ]

## eff  ( 'a', "A\tB", 3  )
f says [ a A    B 3 ]
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Does that clear things up for you?

Actually, it didn't. I don't see how to incorporate that into the following. print_definitions will not be the only subroutine that I may want to parse from within the __DATA__ of a document which is being parsed by print_story.

The very first line is confusing with the two hyphens you put after the shebang. I looked at Safe, and don't understand what the big deal is, since all blocks to me are separate compartments of code to begin with. I take it that $str is equivalent to __DATA__ in your example. I have no idea what my $namespace = __PACKAGE__; is doing. I see you created a dispatch table, but it appears empty of anything that looks like what I'm trying to do.

print_story is the subroutine I've used the most throughout my site. You've latched onto print_definitions when in the future there could be print_table, print_list, print_monster, print_books, and more. I'd like to put them in __DATA__ when I want to include them within the body of my text.

sub print_story {
  my ($source,$html) = @_;
  my $tab = $html ? 3 : 4;

  start_html() if $html;
  while (my $line = <$source>) {
    chomp($line);
    if ($line =~ m/^&/) {
      # This is where the code would go to parse the subroutines
      # within __DATA__. The subroutines to be parsed would be 
      # preceded with an &.
    }
    elsif ($line =~ m/^</) {
      line($tab,$line);
    }
    elsif ($line =~ /^[1-6]\s/) {
      my ($heading,$text) = split(/ /,$line,2);
      line($tab,qq(<h$heading>$text</h$heading>));
    }
    else {
      line($tab,qq(<p>$line</p>));
    }
  }
  line($tab,qq(<p class="author">written by $user</p>)) if $tab == 3;
  end_html if $html;
}
[download]

If you could point me to a few perldocs to explain some of what you did and how to incorporate it into print_story I'd be grateful.

Have a cookie and a very nice day!
Lady Aleena