A universal pointer to a member function as a template parameter inside another class

Question

My question is similar to this one . And the answer is "Karek S.B." really helped me. I have the following classes:

Base.h:

class Base{ public: Base(){} virtual ~Base(){} virtual void init() = 0; }; 

A1.h:

 #include <iostream> #include "Base.h" using namespace std; class A1 : public Base{ public: A1(){} virtual ~A1(){}; virtual void init(){ cout << "A1::init() called" << endl; } void f1(){ cout << "Im in A1::f1" << endl; } void f2(int val){ cout << "Im in A1::f2 with val: " << val << endl; } }; 

I have another class that should be able to store any common member function with any type and number of arguments. The class looks something like this:

MFholder.h:

 #include <functional> #include <deque> using namespace std; class MFHolder{ public: MFHolder(){}; ~MFHolder(){}; template<typename T, typename R, typename ... Args> R addMF(T & obj, R (T::*pf)(Args ...), Args&& ... args){ mfp.push_back(function<void()>(bind(pf, &obj, forward<Args>(args) ...))); } void runTasks(){ while(!mfp.empty()){ auto task = mfp.front(); mfp.pop_front(); task(); } } private: deque< function<void()> > mfp; }; 

Now I want to add some member function to MFHolder from main: main.cpp:

 #include "A1.h" #include "MFHolder.h" int main(){ MFHolder mfh; A1 a1Obj; //A2 a2Obj; //this should also work int val = 42; //mfh.addMF(a1Obj, &A1::f1); //this should also work mfh.addMF(a1Obj, &A1::f2, val); //add some more function calls here... //run all the tasks mfh.runTasks(); return 0; } 

When compiling my code, the following error occurs.

there is no corresponding function to call 'MFHolder::addMF(A1&, void (A1::*)(int), int&)'

And the candidate:

 template<class T, class R, class ... Args> R MFHolder::addMF(T&, R (T::*)(Args ...), Args&& ...) 

thanks in advance!:)

Answer 1

Either change Args && to Args & in the definition of addMF or change val to move (val) when called.