如何在Visual Studio 11中直接将成员函数绑定到std ::函数？ [英] How to directly bind a member function to an std::function in Visual Studio 11?

问题描述

我可以很容易地将成员函数绑定到一个 std :: function ，通过用一个带有capture子句的lambda表达式包装。

I can easily bind member functions to a std::function by wrapping them with a lambda expression with capture clause.

class Class
{
    Class()
    {
        Register([=](int n){ Function(n); });
    }

    void Register(std::function<void(int)> Callback)
    {

    }

    void Function(int Number)
    {

    }
};

但我想直接绑定它们，像下面这样。

But I want to bind them directly, something like the following.

// ...
Register(&Class::Function);
// ...

我认为根据C ++ 11标准，应该支持。但是，在Visual Studio 11中，我得到这些编译器错误。

I think according to the C++11 standard, this should be supported. However, in Visual Studio 11 I get these compiler errors.

错误C2440：'newline'：无法从'int' *'

error C2440: 'newline' : cannot convert from 'int' to 'Class *'

错误C2647：'。*'：不能在'int'上解引用'void（__thiscall Class :: *

error C2647: '.*' : cannot dereference a 'void (__thiscall Class::* )(int)' on a 'int'

推荐答案

我认为根据C ++ 11标准，支持

I think according to the C++11 standard, this should be supported

不是真的，因为非静态成员函数有一个类型为（cv-qualified）的隐式第一个参数 YourType * ，因此在这种情况下它不匹配 void（int）。因此需要 std :: bind ：

Not really, because a non-static member function has an implicit first parameter of type (cv-qualified) YourType*, so in this case it does not match void(int). Hence the need for std::bind:

Register(std::bind(&Class::Function, PointerToSomeInstanceOfClass, _1));

例如

Class c;
using namespace std::placeholders; // for _1, _2 etc.
c.Register(std::bind(&Class::Function, &c, _1));

编辑您提到这是用相同的 Class 实例。在这种情况下，你可以使用一个简单的非成员函数：

Edit You mention that this is to be called with the same Class instance. In that case, you can use a simple non-member function:

void (int n) foo
{
  theClassInstance.Function(n);
}

然后

Class c;
c.Register(foo);

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