#!/usr/bin/perl

use warnings;
use strict;

package Model {

    sub new {
        my $classname = shift;
        my $self = { controller => shift};
        return bless($self, $classname);
    }

    sub calculateThreePlusFour {
        my $self = shift;
        return 3 + 4;
    }
}

package View {

    sub new {
        my $classname = shift;
        my $self = { controller => shift};
        return bless($self, $classname);
    }

    sub showResult {
        my $self = shift;
        my $result = shift;
        print "$result\n";
    }
}

package Controller {

    sub new {
        my $classname = shift;
        my $self = {};
        $self->{model} = Model->new($self);
        $self->{view} = View->new($self);
        return bless($self, $classname);
    }

    sub run {
        my $self = shift;
        my $result = $self->{model}->calculateThreePlusFour();
        $self->{view}->showResult($result);
    }

}

my $controller = Controller->new();
$controller->run();