interface test{

public function Ontest();

}

class caincommand{

private $_command=array();

public function addOrder($command){

$this->_command[]=$command;

}

public function testd($name,$arg){

foreach($this->_command as $a){

if($a->Ontest() == $name){

echo $name;

}

}

}

}

class testDog implements test{

public function Ontest(){

return 'dog';

}

}

class testCat implements test{

public function Ontest(){

return 'cat';

}

}

$dog = new testDog();

$cat = new testCat();

$cain = new caincommand();

$cain->addOrder($dog);

$cain->addOrder($cat);

//$cain->testd('dog','null');

$cain->testd('cat','null');

自己测试的,具体在框架中大家自己体会.