PHP pa和ma

<?php

class Mouse
{
    private $color;
    public $sex;

    public function __construct($role){
        switch($role){
            case 'pa':
                $this->color = 'black';
                $this->sex = 'male';
                break;
            case 'ma':
                $this->color = 'white';
                $this->sex = 'female';
                break;
            default:
                throw new Exception('pa Or ma,please!');
        }
    }

    public function getColor(Mouse $mouse){
        if($mouse->sex == $this->sex){
            var_dump($this->color);
        }else{
            var_dump('*****');
        }
    }

    public function mateWithMa(Mouse $ma){
        if($this->sex == 'male' && $ma->sex = 'female'){
            var_dump('You have been trust by ma');
            $ma->color = $this->color;
            var_dump("success to mate! ma's color :" .($ma->color));
        }
    }

    public function mateWithPa(Mouse $pa){
        if($this->sex == 'female' && $pa->sex == 'male'){
            var_dump('You have been trust by pa');
            $pa->color = $this->color;
            var_dump("success to mate! pa's color :" .($pa->color));
        }
    }
}

var_dump('The First Couple :');
$pa1 = new Mouse('pa');
$ma1 = new Mouse('ma');
$pa1->mateWithMa($ma1);
$ma1->mateWithPa($pa1);

echo "
";

var_dump('The Second Couple :');
$pa2 = new Mouse('pa');
$ma2 = new Mouse('ma');
$ma2->mateWithPa($pa2);
$pa2->mateWithMa($ma2);

此文相关php知识点见 ：http://www.php-internals.com/book/?p=chapt05/05-03-class-visibility