#!/usr/bin/perl
use warnings;
use strict;
use Data::Dumper;
sub f {
    my $in = shift;    
    my (@tmp) = $in =~ /(\w+)/g;
    print(Dumper(\@tmp));
}
f("foo");
f("foo,bar");

__END__
$VAR1 = [
          'foo'
        ];
$VAR1 = [
          'foo',
          'bar'
        ];