设计模式之状态模式

目标：当一个对象的行为取决于它的状态，并且它必须在运行时刻根据状态改变它的行为时，可考虑使用状态模式。

示例代码：
#include

using namespace std;

class Work;
class ForenoonState;
class NoonState;

class State
{
public:
    virtual void WriteProgram(Work* w)=0;
};

class Work
{
private:
    State* current;
public:
    double hour;
public:
    Work();
    void SetState(State* temp)
    {
        current = temp;
    }
   
    void WriteProgram()
    {
        current->WriteProgram(this);
    }
};

class NoonState : public State
{
public:
    virtual void WriteProgram(Work* w)
    {
         cout << "execute" << endl;
         if((w->hour) < 13)
        {
            cout << "还不错了" << endl;
        }
        else
        {
            cout << "不行了,还是睡觉吧" << endl;
        }
    }
};

class ForenoonState : public State
{
public:
    virtual void WriteProgram(Work* w)
    {
        if((w->hour) < 12)
        {
            cout << "现在的精神无敌好" << endl;
        }
        else
        {
            w->SetState(new NoonState());
           w->WriteProgram();    //
       }
    }
};

Work::Work()
{
    current = new ForenoonState();
}

//客户端
int main()
{
    Work* mywork = new Work();
    mywork->hour = 9;
    mywork->WriteProgram();
    mywork->hour = 14;
    mywork->WriteProgram();
   
    return 0;
}