getting close to a 0.07 release

[gitmo/Class-MOP.git] / t / 050_class_mixin_composition.t

#!/usr/bin/perl

use strict;
use warnings;

use Test::More tests => 4;

=pod

Scala Style Class Mixin Composition

L<http://scala.epfl.ch/intro/mixin.html>

A class can only be used as a mixin in the definition of another 
class, if this other class extends a subclass of the superclass 
of the mixin. Since ColoredPoint3D extends Point3D and Point3D 
extends Point2D which is the superclass of ColoredPoint2D, the 
code above is well-formed.

  class Point2D(xc: Int, yc: Int) {
    val x = xc;
    val y = yc;
    override def toString() = "x = " + x + ", y = " + y;
  }
  
  class ColoredPoint2D(u: Int, v: Int, c: String) extends Point2D(u, v) {
    val color = c;
    def setColor(newCol: String): Unit = color = newCol;
    override def toString() = super.toString() + ", col = " + color;
  }
  
  class Point3D(xc: Int, yc: Int, zc: Int) extends Point2D(xc, yc) {
    val z = zc;
    override def toString() = super.toString() + ", z = " + z;
  }
  
  class ColoredPoint3D(xc: Int, yc: Int, zc: Int, col: String)
        extends Point3D(xc, yc, zc)
        with ColoredPoint2D(xc, yc, col);
        
  
  Console.println(new ColoredPoint3D(1, 2, 3, "blue").toString())
        
  "x = 1, y = 2, z = 3, col = blue"
  
=cut

{
    package Point2D;
    use metaclass;
    
    Point2D->meta->add_attribute('$x' => (
        accessor => 'x',
        init_arg => 'x',
    ));
    
    Point2D->meta->add_attribute('$y' => (
        accessor => 'y',
        init_arg => 'y',
    ));    
    
    sub new {
        my $class = shift;
        $class->meta->new_object(@_);
    }    
    
    sub toString {
        my $self = shift;
        "x = " . $self->x . ", y = " . $self->y;
    }
    
    package ColoredPoint2D;
    our @ISA = ('Point2D');
    
    ColoredPoint2D->meta->add_attribute('$color' => (
        accessor => 'color',
        init_arg => 'color',
    ));    
    
    sub toString {
        my $self = shift;
        $self->SUPER() . ', col = ' . $self->color;
    }
    
    package Point3D;
    our @ISA = ('Point2D');
    
    Point3D->meta->add_attribute('$z' => (
        accessor => 'z',
        init_arg => 'z',
    ));        

    sub toString {
        my $self = shift;
        $self->SUPER() . ', z = ' . $self->z;
    }
    
    package ColoredPoint3D;
    our @ISA = ('Point3D');    
    
    __PACKAGE__->meta->mixin('ColoredPoint2D');
    
}

my $colored_point_3d = ColoredPoint3D->new(x => 1, y => 2, z => 3, color => 'blue');
isa_ok($colored_point_3d, 'ColoredPoint3D');
isa_ok($colored_point_3d, 'Point3D');
isa_ok($colored_point_3d, 'Point2D');

is($colored_point_3d->toString(),
   'x = 1, y = 2, z = 3, col = blue',
   '... got the right toString method');