策略模式

策略模式：定义了算法族，分别封装起来，让他们之间可以相互替换，此模式让算法的变化独立于使用算法的客户

1.找出代码中可能变化之处，把他们独立出来，不要和那些不变化的代码混在一起

2.针对借口编程，而不是针对实现编程

3.多用组合少用继承

namespace DesignPatternStrategyPattern;

    //定义行为借口
    Interface FlyBehavior
    {
        public function fly();
    }

    Interface QuakeBehavior
    {
        public function Quake();
    }
 
    //定义鸭子抽象类
    abstract class Duck 
    {
        protected $fly;
        protected $quake;

        public function __construct(FlyBehavior $fly, QuakeBehavior $quake)
        {
            $this -> fly = $fly;
            $this -> quake = $quake;
        }

        public function fly()
        {
            $this -> fly -> fly();
        }

        public function quake()
        {
            $this -> quake -> quake();
        }

        public function setFlyBehavior(FlyBehavior $fly)
        {
            $this -> fly = $fly;
        }

        public function setQuakeBehavior(QuakeBehavior $quake)
        {
            $this -> quake = $quake;
        }
    }

具体实现的分离

class HomeDock extends Duck
    {
        public function cooked()
        {
            echo "home duck be cooked
";
        }
    }

    class WildDuck extends Duck
    {
        public function hunter()
        {
            echo "wild duck is hunting
";
        }
    }

    class FlyPeace implements FlyBehavior
    {
        public function fly()
        {
            echo "fly peace
";
        }
    }

    class FlyRocket implements FlyBehavior
    {
        public function fly()
        {
            echo "fly like rocket
";
        }
    }

    class BoomQuake implements QuakeBehavior
    {
        public function quake()
        {
            echo "quake like a boom
";
        }
    }

    $homedock = new HomeDock(new FlyRocket, new BoomQuake);
    $homedock -> cooked();
    $homedock -> quake();
    $homedock -> fly();
    $homedock -> setFlyBehavior(new FlyPeace);
    $homedock -> fly();

输出

home duck be cooked
quake like a boom
fly like rocket
fly peace