使用 C++ 类成员函数作为 C 回调函数

Using a C++ class member function as a C callback function(使用 C++ 类成员函数作为 C 回调函数)

问题描述

我有一个 C 库，需要注册一个回调函数来自定义一些处理.回调函数类型为int a(int *, int *).

I have a C library that needs a callback function to be registered to customize some processing. Type of the callback function is int a(int *, int *).

我正在编写类似于以下的 C++ 代码，并尝试注册一个 C++ 类函数作为回调函数:

I am writing C++ code similar to the following and try to register a C++ class function as the callback function:

class A {
  public:
   A();
   ~A();
   int e(int *k, int *j);
};

A::A()
{
   register_with_library(e)
}

int
A::e(int *k, int *e)
{
  return 0;
}

A::~A() 
{

}

编译器抛出以下错误:

In constructor 'A::A()',
error:
 argument of type ‘int (A::)(int*, int*)’ does not match ‘int (*)(int*, int*)’.

我的问题:

1. 首先，是否可以像我尝试的那样注册 C++ 类成员函数，如果可以，如何注册?(我在 http://www.parashift 阅读了 32.8.com/c++-faq-lite/mixing-c-and-cpp.html.但在我看来它并没有解决问题)
2. 是否有替代/更好的方法来解决这个问题?

1. First of all is it possible to register a C++ class memeber function like I am trying to do and if so how? (I read 32.8 at http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html. But in my opinion it does not solve the problem)
2. Is there a alternate/better way to tackle this?

推荐答案

如果成员函数是静态的，你可以这样做.

You can do that if the member function is static.

A 类的非静态成员函数有一个 class A* 类型的隐式第一个参数，它对应于 this 指针.这就是为什么你只能在回调的签名也有 class A* 类型的第一个参数时注册它们.

Non-static member functions of class A have an implicit first parameter of type class A* which corresponds to this pointer. That's why you could only register them if the signature of the callback also had the first parameter of class A* type.

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