策略模式(strategy pattern)

標籤：

策略模式：

    定義了一個演算法族，分別把每個演算法封裝起來，讓它們之間可以互相替換，此模式讓演算法的變化獨立於使用演算法的客戶。

結構圖：

C++實現：

class calculateStrategy {public:    virtual int calculate(int value1, int value2) = 0;};class Plus : public calculateStrategy {public:    int calculate(int value1, int value2) { return value1 + value2;}};class Minus : public calculateStrategy {public:    int calculate(int value1, int value2) { return value1 - value2;}};class Calculator {private:    calculateStrategy *cs;public:    Calculator(calculateStrategy *strategy): cs(strategy) {}    int calculate(int value1, int value2)    {        return cs->calculate(value1, value2);    }    void setStrategy(calculateStrategy *strategy) { cs = strategy; };    ~Calculator() { delete cs; }};int main(){    calculateStrategy *strategy = new Plus;    Calculator cal(strategy);    cout << cal.calculate(1, 2) << endl;    delete strategy;    strategy = new Minus;    cal.setStrategy(strategy);    cout << cal.calculate(1, 2) << endl;    //delete strategy;}

 

策略模式(strategy pattern)