绑定成员函数的正确方法？

Question

我有以下代码：

#include <iostream>
#include <vector>
#include <functional>

using namespace std;
using namespace std::placeholders;

typedef std::vector<std::function<void(void)>> func_list;

class Thing {
private:
    func_list flist;
    void _sayHi() {
        cout << "hi" << endl;
    }
    void _sayNum(int num) {
        cout << num << endl;
    }
public:
    Thing();
    void sayHi();
    void sayNum(int num);
    void executeFunctions();
};

void Thing::sayHi() {
    flist.push_back(
        std::bind(&Thing::_sayHi, this)  //  Unsure of the correct usage here
    );
}

void Thing::sayNum(int num) {
    flist.push_back(
        std::bind(&Thing::_sayNum, this, num)  //  Unsure of the correct usage here
    );
}

void Thing::executeFunctions() {
    for (unsigned int i = 0; i < flist.size(); i++) {
        flist.at(i)();
    }
}

int main() {
    Thing thing = Thing();
    thing.sayHi();
    thing.sayNum(5);

    thing.executeFunctions();
}

我的目标只是在调用函数时存储函数，以便稍后执行。我可以使用 std::bind(&functionName, param1, param2) 绑定非成员函数，但在函数内部这不再有效，使用 std::bind(&Class::ClassMemberFunctionName, this) 给我留下 unresolved externals 错误：

Error 1 error LNK2019: unresolved external symbol "public: __thiscall Thing::Thing(void)" (??0Thing@@QAE@XZ) referenced in function _main

Error 2 error LNK1120: 1 unresolved externals

绑定此 class 函数的正确方法是什么？

Answer 1

您缺少 Thing::Thing() 构造函数的实现。

绑定成员函数的正确方法？

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