#!/usr/bin/perl -w
use strict;

my $a = new A();
$a->pass_sub();


package A;
use B;

sub new {
    my ( $class, ) = @_;

    my $self  = { };
    bless $self, ref($class) || $class;

    return $self;
}

sub pass_sub {
    my ( $self, ) = @_;

    $self->{'sub_handler'} = new B();
    $self->{'sub_handler'}->use_sub_later( sub { $self->say_hello } );
}

sub say_hello {
    my ( $self, ) = @_;
    print "Hello! Args: ". join(',', @_) ."\n";
}

1;


package B;

sub new {
    my ( $class, ) = @_;

    my $self  = { };
    bless $self, ref($class) || $class;

    return $self;
}

sub use_sub_later {
    my ( $self, $sub, ) = @_;

    my $ready_to_use = 1;
    $sub->('ARG1', 'ARG2') if $ready_to_use;
}

1;