Question

我试图用C ++理解观察者模式。我基本上是在尝试使用模板来编写一个简单的程序来理解它，我必须承认我不是那个用模板编程的诗句，因为它我无法解决这个编译错误。如果有人能请点，那会很棒出于我做错了什么

#include<iostream>
#include<conio.h>
#include<list>
#include<Windows.h>
using namespace std;

template <class T>
class IEventListener
{
public:
  virtual ~IEventListener() {}
  virtual void onEvent(T eventData) = 0;
};

template <class T>
class EventGenerator
{
public:
  EventGenerator(){}
  virtual ~EventGenerator() {}
  void addListener(IEventListener<T> l)
  {
    listeners.push_back(l);
  }

  void trigger(T eventData)
  {
    for (auto it = listeners.begin(); it != listeners.end(); ++it)
    {
      (*it).onEvent(eventData);
    }
  }
private:
  std::list<IEventListener<T>> listeners;
};

class IntListener : public IEventListener<int>
{
public:
  //event callback
  virtual void onEvent(int eventData)
  {
    std::cout << "int" <<eventData<< std::endl;
  }
};

class ActualIntEventGenerator : public EventGenerator<int>    
{
public:
  void firstMethod()
  {
    int a = 10;
    trigger(a);
  }
};

void main()
{
  IntListener i;
  ActualIntEventGenerator intGenerator;
  intGenerator.addListener(i);
  Sleep(5000);
}

我得到的错误是

error C2259: 'IEventListener<int>' : 
cannot instantiate abstract class due to following members:
void IEventListener<int>::onEvent(T)' : is abstract with [T=int]

提前致谢

错误C2259：无法实例化抽象类

0 个答案: