CODEWITHSUNDEEP
c++c++11
yaodav
yaodav

Reputation: 1276

Assign a member function pointer as a callback from another function

I have a class A that has a function pointer for a callback. The default values are some function pointer from class A but I want to assign a function pointer from class B. I tried std::function and std::bind but it is not working. I tried to use this answer but without success.

The code is:

#include <iostream>
#include <string>
#include <functional>

class A{
public:
    typedef void(*action)() ;

    A( std::function<void()> a  = nullptr)
    {
        if(a)
            m_Func = a; 
        else
            m_Func = std::bind( (this->*(this->dummyFunction))() );
    }
    std::function<void(void)> m_Func;
    void dummyFunction(void){std::cout<<"dummy function\n" <<std::endl;}
};

class B{
public:
    std::function<void()> m_Bfunc(){ std::cout << "class B func\n" <<std::endl;}
};

int main()
{
  B b;
  A a(b.m_Bfunc);
  a.m_Func();
}

I want that the function m_Bfunc to run.

Upvotes: 0

Views: 84

Answers (1)

Jarod42
Jarod42

Reputation: 218268

It seems you want:

class A{
public:
    A(std::function<void()> a = nullptr)
    {
        if(a)
            m_Func = a; 
        else
            m_Func = [this](){ dummyFunction(); };
    }
    std::function<void()> m_Func;
    void dummyFunction(){std::cout<<"dummy function\n" <<std::endl;}
};

class B{
public:
    void func(){ std::cout << "class B func\n" <<std::endl;}
};

int main()
{
  B b;
  A a([&](){b.func(); });
  a.m_Func();
}

Demo

Upvotes: 1

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