Question

I want to make a class, let’s name it class A, that executes functions from other classes. So I want to inherit my classes from this A class and class A to be able to receive function addresses from the derived classes and execute them.

This is what I thought so far:

#include <iostream>
using namespace std;

template <class T>
class A
{
public:
    // a typedef for the function I want to execute 
    // which has no parameters and void as return type
    typedef void (T::*SpecialFunc)();

    A() { }

    //this is the function that executes the received functions
    void exec(SpecialFunc func)
    {
        ((new T)->*func)();
    }
};

class B : public A<B>
{
public:
    B()
    {
        // call A::exec to call my function
        exec(&B::funcB);
    }

    //function I want to be executed
    void funcB()
    {
        cout << "testB\n";
    }
};

int main()
{
    B ob;

    return 0;
}

What I want is function funcB to be called. So far my program breaks with no error, just heavily breaks.
I know that this code can’t work because I try to build class A that needs information from class B and class B needs information from the first class A to be constructed but I hope you understand better what I’m willing to achieve.

Can this be achieved?

Thank you

Answer 1

Looks like you have infinite recursion here. You call exec() in constructor of B, it creates new B object by new statement which calls constructor of B which calls exec() etc. Probably you need to pass ponter or reference to B object to exec() to avoid its construction.

And of course B object leak in exec() doesn’t look good. I hope it’s just for testing purposes…