用 C++ 实现 C# 中的委托/事件 (3-functor0)

最新推荐文章于 2016-11-17 22:38:26 发布

原创最新推荐文章于 2016-11-17 22:38:26 发布 · 795 阅读

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CC 4.0 BY-SA版权

文章标签：

#c++ #c# #functor #fp #class #null

作者看程序员杂志后，热衷于用C++模拟C#中的委托/事件并给出代码。提到VC6不支持偏特化，影响代码使用。还指出没有返回值的函数用delegate，否则用delegate_rt，functor也类似，boost里有现成委托但VC6可能用不了，代码用于个人研究。

前两天看程序员杂志
看到关于 C# 中的委托/事件
觉得用起来好像是挺方便的
本人热衷于 C++
想想用 C++ 来模拟似乎也可以
于是就有了下面的代码...
(VC6 不支持偏特化本人工作环境就是 VC6 痛啊~~~)

没有返回值的函数用 delegate
否则就用 delegate_rt
functor 也一样 functorN/functorN_rt
delegate 的模板参数可以是函数指针(非成员函数)
也可以是 functor
还可以是 delegate
functor 可用 make_functor/make_functor_rt 来生成
要是有偏特化就可以去掉讨厌的 _rt 了 :(

关于委托 boost里有现成的
不过可能 VC6 里用不了

这些代码旨在个人研究
如果大家发现其中问题希望能指出

//filename: functor0.h
#ifndef _FUNCTOR0_H_
#define _FUNCTOR0_H_


class functor0
{
  class deleobject
  {
  };
  typedef void (*func_pt)();
  typedef void (deleobject::*mem_func_pt)();
  typedef void (deleobject::*cmem_func_pt)() const;
  functor_base<deleobject,
    func_pt, 
    mem_func_pt, 
    cmem_func_pt> base;
  
  public: 
    functor0() : base() {}
    functor0(func_pt pf) : base(pf) {}
    template<typename T> 
      functor0(const T *pObject, void (T::*fp)()) :
        base((const deleobject*)(pObject), 
          *((mem_func_pt*)(&fp))) {}
    template<typename T> 
      functor0(const T &pObject, void (T::*fp)()) :
        base((const deleobject*)(pObject), 
          *((mem_func_pt*)(&fp))) {}
    template<typename T> 
      functor0(const T *pObject, void (T::*fp)() const) :
        base((const deleobject*)(pObject), 
          *((cmem_func_pt*)(&fp))) {}
    template<typename T> 
      functor0(const T &pObject, void (T::*fp)() const) :
        base((const deleobject*)(pObject), 
          *((cmem_func_pt*)(&fp))) {}
  bool operator !=(const functor0& rhs) const { return !(*this == rhs); }
  bool operator ==(const functor0& rhs) const
  {
    return base == rhs.base;
  }
  bool operator ==(const void* rhs) const
  {
    return base == rhs;
  }
  functor0& operator =(const functor0& rhs)
  {
    base = rhs.base;
    return *this;
  }
  void operator()() const
  {
    if (base.m_pObject == NULL)
      (*base.m_pf)();
    else
      (base.m_pObject->*(base.m_pmf))();
  }
};


inline functor0 make_functor(void (*fp)())
{
  return functor0(fp);
}

template <class T>
inline functor0 make_functor(const T* tp, void (T::*fp)())
{
  return functor0(tp, fp);
}

template <class T>
inline functor0 make_functor(const T* tp, void (T::*fp)() const)
{
  return functor0(tp, fp);
}

#endif // #ifndef _FUNCTOR0_H_

//filename: functor0_rt.h
#ifndef _FUNCTOR0_RT_H_
#define _FUNCTOR0_RT_H_

template <typename R>
class functor0_rt
{
  class deleobject
  {
  };
  typedef R (*func_pt)();
  typedef R (deleobject::*mem_func_pt)();
  typedef R (deleobject::*cmem_func_pt)() const;
  functor_base<deleobject,
    func_pt, 
    mem_func_pt, 
    cmem_func_pt> base;
  
  public: 
    functor0_rt() : base() {}
    functor0_rt(func_pt pf) : base(pf) {}
    template<typename T> 
      functor0_rt(const T *pObject, R (T::*fp)()) :
        base((const deleobject*)(pObject), 
          *((mem_func_pt*)(&fp))) {}
    template<typename T> 
      functor0_rt(const T &pObject, R (T::*fp)()) :
        base((const deleobject*)(pObject), 
          *((mem_func_pt*)(&fp))) {}
    template<typename T> 
      functor0_rt(const T *pObject, R (T::*fp)() const) :
        base((const deleobject*)(pObject), 
          *((cmem_func_pt*)(&fp))) {}
    template<typename T> 
      functor0_rt(const T &pObject, R (T::*fp)() const) :
        base((const deleobject*)(pObject), 
          *((cmem_func_pt*)(&fp))) {}
  bool operator !=(const functor0_rt& rhs) const { return !(*this == rhs); }
  bool operator ==(const functor0_rt& rhs) const
  {
    return base == rhs.base;
  }
  bool operator ==(const void* rhs) const
  {
    return base == rhs;
  }
  functor0_rt& operator =(const functor0_rt& rhs)
  {
    base = rhs.base;
    return *this;
  }
  R operator()() const
  {
    if (base.m_pObject == NULL)
      return (*base.m_pf)();
    else
      return (base.m_pObject->*(base.m_pmf))();
  }
};

template <typename R>
inline functor0_rt<R> make_functor_rt(R (*fp)())
{
  return functor0_rt<R>(fp);
}

template <typename R, class T>
inline functor0_rt<R> make_functor_rt(const T* tp, R (T::*fp)())
{
  return functor0_rt<R>(tp, fp);
}

template <typename R, class T>
inline functor0_rt<R> make_functor_rt(const T* tp, R (T::*fp)() const)
{
  return functor0_rt<R>(tp, fp);
}

#endif // #ifndef _FUNCTOR0_RT_H_