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


package FH;

sub new {
    bless { };
}

sub Print {
    print "Running FH::Print\n";
}


package main;

sub Prunt {
    print "Running main::Prunt\n";
}

my $fh = FH->new;
print '$fh is an ', ref $fh, "\n";
Print $fh;
$fh->Print;
[download]

The explanation is that print $fh makes Perl look for Print in the current package before looking in $fh's package, whereas $fh->Print looks only in $fh's class and any base classes.

On another subject completely, this demo program violates another 'always, always, always' rule that people often mention: always pass the class name as the first argument of a constructor and bless the new object into the package supplied to you rather than the current package. I think that's unnecessary. Any derived package can call your constructor and then rebless the new object into itself.

IMHO, one of several problems that make OOP unnecessarily difficult in Perl 5 is that a constructor can't easily and efficiently tell whether it was invoked as pkg->new or pkg::new (in other words, whether the package name was passed as the first arguemnt or not, and therefore where in @_ the 'real' arguments begin). Most people use the former, but the latter is more efficient because it passes one argument fewer. Perl 6 fixes this problem, along with so many others.

Markus