在一个类中使用带成员函数的通用std :: function对象 [英] Using generic std::function objects with member functions in one class

问题描述

对于一个类，我想在同一个类的成员函数中存储一些函数指针 map 存储 std :: function 对象。但是我在这段代码的开头失败了：

For one class I want to store some function pointers to member functions of the same class in one map storing std::function objects. But I fail right at the beginning with this code:

class Foo {
    public:
        void doSomething() {}
        void bindFunction() {
            // ERROR
            std::function<void(void)> f = &Foo::doSomething;
        }
};

我收到错误C2064：term不会计算为一个函数， 在 xxcallobj 加上一些奇怪的模板实例化错误。目前我在Windows 8与Visual Studio 2010/2011和Win 7与VS10的工作失败了。该错误必须基于一些奇怪的C ++规则，我不遵循。

I receive error C2064: term does not evaluate to a function taking 0 arguments in xxcallobj combined with some weird template instantiation errors. Currently I am working on Windows 8 with Visual Studio 2010/2011 and on Win 7 with VS10 it fails too. The error must be based on some weird C++ rules i do not follow.

编辑：我做不使用boost。这是C ++ 11集成在MS编译器中。

I do NOT use boost. This is C++11 integrated in the MS compiler.

推荐答案

非静态成员函数必须用对象调用。也就是说，它总是隐式传递this指针作为其参数。

A non-static member function must be called with an object. That is, it always implicitly passes "this" pointer as its argument.

因为你的 std :: function 指定您的函数不接受任何参数（< void（void）> ），必须绑定 ）参数。

Because your std::function signature specifies that your function doesn't take any arguments (<void(void)>), you must bind the first (and the only) argument.

std::function<void(void)> f = std::bind(&Foo::doSomething, this);

如果要使用参数绑定函数，则需要指定占位符：

If you want to bind a function with parameters, you need to specify placeholders:

using namespace std::placeholders;
std::function<void(int,int)> f = std::bind(&Foo::doSomethingArgs, this, _1, _2);

或者，如果你的编译器支持C ++ 11 lambdas：

Or, if your compiler supports C++11 lambdas:

std::function<void(int,int)> f = [=](int a, int b) {
    this->doSomethingArgs(a, b);
}

（我手头没有C ++ 11编译器现在，所以我不能检查这一个。）

(I don't have a C++11 capable compiler at hand right now, so I can't check this one.)

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