C++11应用：观察者模式(多函数对象回调)

    CallbackNotify.hpp

#pragma once

#include <map>

template <typename Func>
class CallbackNotify
{
private:
	CallbackNotify(const CallbackNotify&) = delete; // 禁用复制函数
	CallbackNotify& operator= (const CallbackNotify&) = delete; // 禁用赋值构造

	int m_observerId = 0; // 观察者对应的编号
	std::map<int, Func> m_connections; // 观察者列表

									   // 保存观察者并分配观察者编号
	template <typename F>
	int Assign(F&& f)
	{
		int k = m_observerId++;
		m_connections.emplace(k, std::forward<F>(f));
		return k;
	}
public:
	CallbackNotify() = default;// 使用C++11提供的默认构造函数
	virtual ~CallbackNotify() {
		m_connections.clear();
		m_observerId = 0;
	}
	// 注册观察者，支持右值引用
	int Connect(Func&& f)
	{
		return Assign(f);
	}
	// 移除观察者
	void Disconnect(int key)
	{
		m_connections.erase(key);
	}
	// 通知所有观察者
	template <typename... Args>
	void Notify(Args&&... args)
	{
		for (auto& it : m_connections)
		{
			it.second(std::forward<Args>(args)...); // 函数对象执行参数
		}
	}
};

    测试：

#include <iostream>
#include <string>  

#include <functional>

#include "CallbackNotify.hpp"

using namespace std;
   
struct TestA
{
	int a;
	int b;
	void print(int x, int y)
	{
		cout << "TestA print:" << x << "," << y << endl;
	}
	void printNoParam() {
		cout << "TestA printNoParam:" << a << "," << b << endl;
	}
};

void printLocal(int a, int b) {
	cout << "printLocal:" << a << "," << b << endl;
}

void test() {
	CallbackNotify<std::function<void(int, int)>> myevent; // 申明注册的函数对象是两个参数的int
	auto key1 = myevent.Connect(std::move(printLocal)); // 以函数方式注册观察者

	TestA testA;
	auto key2 = myevent.Connect([&testA](int a, int b) {testA.a = a; testA.b = b; }); // lambda注册

	auto key3 = myevent.Connect([](int a, int b) {cout << "lambda print:" << a << "," << b << endl; }); // lambda注册

																										// std::function注册
	std::function<void(int, int)> f1 = std::bind(&TestA::print, &testA, std::placeholders::_1, std::placeholders::_2);
	auto key4 = myevent.Connect(std::move(f1));

	std::function<void(int, int)> f2 = printLocal;
	auto key5 = myevent.Connect(std::move(f2));

	int a = 1;
	int b = 2;
	myevent.Notify(a, b); // 触发

	testA.printNoParam();

	myevent.Disconnect(key1); //移除
	 
}
int main(int, char *[])
{     
	test();

	system("pause");
	return 0;
}