if ( ref($self) eq 'person') { $self->tellName(); }
	if ( ref($self) eq 'child')  {$self->SUPER::tellName();}

##</code><code>##

Hello, I'm Alice.

Hi, I'm Billy The Kid.
Can't locate object method "tellName" via package "person" at ./classtest line 25.
Here's my mom: Hello, I'm

##</code><code>##

#!/usr/bin/perl
use strict;

package person;
sub new
{
	my $class = shift(@_);
	my $self  = { 'name' => 'Alice' };
	bless($self, $class);
	return($self);
}

sub tellName  {
        my($self)=$_[0];
        print "$self->{'name'}.\n";
}

sub introduce {
        my($self)=$_[0];
        print "Hello, I'm ";
        # $self->tellName();   # original code
        # tellName($self);     # one solution offered by perlmonks
	#print "\ndebug info: " . ref($self) . "\n";
	if ( ref($self) eq 'person'){ $self->tellName(); }
	if ( ref($self) eq 'child') { $self->SUPER::tellName();}
}
1;

package child;
our @ISA = qw(person);    # inherits from person
sub new {
	my $class = shift(@_);
	my $self = $class->SUPER::new();
	$self ->{'nickName'} = 'Billy The Kid';
	bless $self, $class;
	return $self;
}

sub tellName  {
        my($self)=$_[0];
        print "$self->{'nickName'}.\n";
}

sub introduce {
        my($self)=$_[0]; print "Hi, I'm ";
        $self->tellName();
        print "Here's my mom: ";
        $self->SUPER::introduce();
}
1;



package main;

my $mom = new person();
$mom->introduce();      # that time it works.

print "\n";

my $son = new child();
$son->introduce();