观察者模式主要使用到了函数指针，类似的结构在linux内核中比较常见。
//C++实现观察者模式
#include<vector>
#include<stdio.h>
#include<iostream>
#include<string>
using namespace std;
template <class Handler>
class event //模板类，这就决定了这个委托可以委托任何类型了函数指针，只要你有，我就能委托
{
public:
event()
{//构造函数
}
vector<Handler>& GetEvent()
{//获取Event列表
return m_HandlerList;
}
virtual void add(const Handler v)
{//虚函数，添加时间到vector中
m_HandlerList.push_back(v);
}
virtual void remove(const Handler v)
{//删除vector
vector<Handler>::iterator it = m_HandlerList.begin();
for (; it != m_HandlerList.end(); it++)
{
if ((*it) == v)
{//如果相等，则删除
m_HandlerList.erase(it);
break;
}
}
}
private:
vector<Handler> m_HandlerList;//时间列表
};
//参数列表为空，EventHandler是函数地址
typedef void (*EventHandler)(void);
class MyClass
{
public:
MyClass(){}
void Notify()
{
size_t nCount = AllEvent.GetEvent().size();
for (size_t i = 0; i < nCount; i++)
{
EventHandler notifyEvent = AllEvent.GetEvent()[i];
(*notifyEvent)();
//另外的两种写法
//(*(AllEvent.GetEvent().at(i)))();
//(*(AllEvent.GetEvent()[i]))();
}
}
public:
event <EventHandler> AllEvent;
};
void MyEventHandler1()
{
printf("This is a event!\n");
}
void MyEventHandler2()
{
printf("This is another event!\n");
}
int main(void)
{
MyClass Obj;
Obj.AllEvent.add(MyEventHandler1);
Obj.AllEvent.add(MyEventHandler2);
Obj.Notify();
Obj.AllEvent.remove(MyEventHandler1);
Obj.Notify();
printf("Over!\n");
system("pause");
return 0;
}