php 介面實現策略模式

<?php/** * 抽象策略角色，以介面實現 * interface只包含方法、委託或事件的簽名； */interface FlyInterface {        public function fly();} /** * 具體策略A:用翅膀飛行 */class FlyWithWing implements FlyInterface {    public function fly() {        echo "我用翅膀飛行\n";    }} /** * 具體策略角色B：用腳飛行 */class FlyWithFoot implements FlyInterface {    public function fly() {        echo "我用腳飛行\n";    }}  /** * 主類角色 */class Duck {    private $_fly;    private $_flyInterface = "FlyWithWing";    /* 引用的策略 */    public function __construct($flyInterface) {        if(!empty($flyInterface)){            $this->_flyInterface = $flyInterface ;        }        $this->_fly = new $this->_flyInterface;    }     public function fly() {        $this->_fly->fly();    } } $ducka = new Duck("FlyWithWing");$ducka->fly();$duckb = new Duck("FlyWithFoot");$duckb->fly();?>