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。

#include <iostream>
#include <string>

using namespace std;


struct FlyBehavior {
public:
    virtual fly() = 0;
};

struct QuackBehavior {
public:
    virtual quack() = 0;
};


struct Duck {
public:
    swim() {}
    virtual display() = 0;
    preformQuack() {
        flyBehavior->fly();
    }
    preformFly() {
        quackBehavior->quack();
    }
    setFlyBehavior(FlyBehavior *mflyBehavior) {
        flyBehavior = mflyBehavior;
    }
    setQuackBehavior(QuackBehavior *mquackBehavior) {
        quackBehavior = mquackBehavior;
    }
protected:
    FlyBehavior *flyBehavior;
    QuackBehavior *quackBehavior;
};


struct FlyWithWings : public FlyBehavior {
    virtual fly() {
        cout << "\tFlyWithWings" << endl;
    }
};

struct FlyNoWay : public FlyBehavior {
    virtual fly() {
        cout << "\tFlyNoWay" << endl;
    }
};

struct Quack : public QuackBehavior {
    virtual quack() {
        cout << "\tQuack" << endl;
    }
};

struct Squeak : public QuackBehavior {
    virtual quack() {
        cout << "\tSqueak" << endl;
    }
};

struct MuteQuack : public QuackBehavior {
    virtual quack() {
        cout << "\tMuteQuack" << endl;
    }
};


struct MallardDuck : public Duck {
    MallardDuck() {
        flyBehavior = new FlyNoWay();
        quackBehavior = new Quack();
    }
    virtual display() {
        cout << "MallardDuck:" << endl;
    }
};

struct ReadheadDuck : public Duck {
    ReadheadDuck() {
        flyBehavior = new FlyWithWings();
        quackBehavior = new MuteQuack();
    }
    virtual display() {
        cout << "ReadheadDuck:" << endl;
    }
};

struct RubberDuck : public Duck {
    RubberDuck() {
        flyBehavior = new FlyWithWings();
        quackBehavior = new Quack();
    }
    virtual display() {
        cout << "RubberDuck:" << endl;
    }
};

struct DecoyDuck : public Duck {
    DecoyDuck() {
        flyBehavior = new FlyNoWay();
        quackBehavior = new Squeak();
    }
    virtual display() {
        cout << "DecoyDuck:" << endl;
    }
};

int main(int argc, char **argv)
{
    MallardDuck *mallardDuck = new MallardDuck();
    ReadheadDuck *readheadDuck = new ReadheadDuck();
    RubberDuck *rubberDuck = new RubberDuck();
    DecoyDuck *decoyDuck = new DecoyDuck();

    mallardDuck->display();
    mallardDuck->preformFly();
    mallardDuck->preformQuack();
    readheadDuck->display();
    readheadDuck->preformFly();
    readheadDuck->preformQuack();
    rubberDuck->display();
    rubberDuck->preformFly();
    rubberDuck->preformQuack();
    decoyDuck->display();
    decoyDuck->preformFly();
    decoyDuck->preformQuack();

    delete mallardDuck;
    delete readheadDuck;
    delete rubberDuck;
    delete decoyDuck;
}