Re: See if a certain package has a certain sub, without executing that sub

[gmax]

Use the can method (it's a method of the UNIVERSAL package, so every class in Perl has access to it).

#!/usr/bin/perl

use strict;
use warnings;

package Communications;

sub SendMessage {
    my $packages = shift;
    my $msg = shift;
    for (@$packages) {
        if ($_->can('ReceiveMessage') ) {
            $_->ReceiveMessage($msg);
        }
        else {
            print "$_ can't ReceiveMessage\n"
        }
    }
}

sub ReceiveMessage {
    print __PACKAGE__, "::ReceiveMessage('$_[1]')\n";
}

package Second;

sub ReceiveMessage {
    print __PACKAGE__, "::ReceiveMessage('$_[1]')\n";
}

package Other;

sub nothing {
    print "\n";
}

package main;

my @packages = qw(Communications Other Second);

Communications::SendMessage( \@packages, 'hello');
__END__
output:
Communications::ReceiveMessage('hello')
Other can't ReceiveMessage
Second::ReceiveMessage('hello')