c# - 当 C++ 使用智能指针时，C# 委托等效

Question

I am mainly a .NET programmer working on a C++ project and am trying to determine the equivalent way to handle delegates that use the Action and Function template types. I use the delegates both as events and callbacks within the .NET code. My C++ project uses smart pointers and the same delegate design patterns as a C# program would. What is the best way to handle this situation? It is not clear to me how to pass and maintain a function pointer that also keeps track of the smart pointer and potentially the deletion of the underlying object since the event container uses a weak reference. The library needs to be multi-platform so using CLR is unfortunately not an option.

Answer 1

您正在寻找的是绑定到现有对象的方法指针，就是这样吗？

你应该看看boost::bind。如果你的环境支持它，你也可以使用std::tr1::bind或者即使std::bind它支持 C++11。

说明您想要的示例是：

struct X
{
    bool f(int a);
};
X x;
shared_ptr<X> p(new X);
int i = 5;

bind(&X::f, ref(x), _1)(i);     // x.f(i)
bind(&X::f, &x, _1)(i);         //(&x)->f(i)
bind(&X::f, x, _1)(i);          // (internal copy of x).f(i)
bind(&X::f, p, _1)(i);          // (internal copy of p)->f(i)

最后两个例子很有趣，因为它们产生了“自包含”的函数对象。bind(&X::f, x, _1) 存储 x 的副本。bind(&X::f, p, _1) 存储 p 的副本，由于 p 是 boost::shared_ptr，因此函数对象保留对其 X 实例的引用，即使 p 超出范围或是重置（）。

对于和之间的区别boost::bind，我让您在 SO 上看到另一个问题。std::tr1::bindstd::bind

Answer 2

看看： http: //www.codeproject.com/Articles/7150/Member-Function-Pointers-and-the-Fastest-Possible

它还将解释为什么 C++ 中的委托有点棘手。这个库是在我读过的游戏开发书中推荐的（所以我假设它非常快）。