一、前言

状态模式理解最基本上的我觉得应该也是够用了，实际用的话，也应该用的是Boost.MSM状态机。

相关代码可以在这里，如有帮助给个star！AidenYuanDev/design_patterns_in_modern_Cpp_20

二、实现

一、UML类图

二、实现

#include <iostream>
#include <memory>
using namespace std;class Light_Switch;
class On_State;
class Off_State;
class State {
public:virtual void on(Light_Switch* ls) = 0;![请添加图片描述](https://i-blog.csdnimg.cn/direct/9c069a22ebae485d8dbd3f084c658e5d.png)virtual void off(Light_Switch* ls) = 0;
};class On_State : public State {
public:On_State() { cout << "灯打开了" << endl; }void on(Light_Switch* ls) override {}void off(Light_Switch* ls) override;
};class Off_State : public State {
public:Off_State() { cout << "灯灭了" << endl; }void on(Light_Switch* ls) override;void off(Light_Switch* ls) override {}
};class Light_Switch {
private:shared_ptr<State> state_;public:Light_Switch() : state_(make_shared<Off_State>()) {}void set_state(shared_ptr<State> state) { state_ = std::move(state); }void on() { state_->on(this); }void off() { state_->off(this); }
};void On_State::off(Light_Switch* ls) {cout << "按下关灯键" << endl;ls->set_state(make_shared<Off_State>());
}void Off_State::on(Light_Switch* ls) {cout << "按下开灯键" << endl;ls->set_state(make_shared<On_State>());
}int main() {auto ls = make_shared<Light_Switch>();ls->on();ls->off();ls->on();return 0;
}