sub document_if {
    my ($cond,$code) = @_;
    if ($cond) { 
        eval $code
    } else {
        print "Not executing:\n";
        print $code;
        print "\n---\n";
    };
};

##</code><code>##

    document_if( 1 == 0, q{
        print "The sky has fallen down.\n";
    });

##</code><code>##

use strict;
use B::Deparse;
my $deparse = B::Deparse->new("-p", "-sC");

sub document_if {
    my ($cond,$code) = @_;
    if ($cond) { 
        $code->()
    } else {
        print "Not executing:\n";
        print $deparse->coderef2text($code);
        print "\n---\n";
    };
};

##</code><code>##

    document_if( 1 == 0, sub{
        print "The sky has fallen down.\n";
    });