c++ store functor in class - c++

Question

I´ve created the following Event class:
Event.h
#ifndef EVENT_H
#define EVENT_H
#include<string>
template<typename T>
class Event
{
public:
T fnktptr; //Error: field ‘Event<int()>::fnktptr’ invalidly declared function type
Event();
virtual ~Event();
};
#endif // EVENT_H
Event.cpp
#include "Event.h"
template<typename T>
Event<T>::Event()
{
//ctor
}
template<typename T>
Event<T>::~Event()
{
//dtor
}
// No need to call this TemporaryFunction() function,
// it's just to avoid link error.
void TemporaryFunction ()
{
Event<int> TempObj;
}
Now I tested it with the following code and it works:
Event<int> event;
int t = 5;
event.fnktptr = t;
But finally, I want to use it with a functor like this:
Event<decltype(consumeInt)> event;
event.fnktptr = consumeInt;
But now I get a Error in the Event.h file:
T fnktptr; //Error: field ‘Event<int()>::fnktptr’ invalidly declared function type

Answer 1

Based on your latest comments, I would say a std::function<> is the best way forward. The example code below assumes you just want to call fnktptr and don't care about the result.
#include <functional>
class Event
{
public:
std::function<void ()> fnktptr;
Event();
virtual ~Event();
};
If you need to capture the result, you will not be able to arbitrarily have different returns for each Event object. You either must pick one or use something like boost::variant<>.
template<class T>
class Event
{
public:
std::function<T ()> fnktptr;
Event();
virtual ~Event();
};
This would allow you to create Event<int> objects for instance to use with consumeInt().
Example:
Event<int> event;
event.fnktptr = consumeInt;