Make Functor from a Lambda Function in C++

Question

Is it possible to create a functor from a lambda function in C++?

If not, why not?

It's giving me a surprising bit of trouble to do.

Practical Use Case:

Another function requires making a functor like so:

Class::OnCallBack::MakeFunctor(this, &thisclass::function);

Typically in order to use this, I have to make a function within thisclass which means adding to the header file. After a lot of uses, there's a good bit of bloat. I want to avoid this bloat by doing something like:

Class::OnCallBack::MakeFunctor(this, 
    void callback()
    { []() { dosomething; } });

What goes wrong is compilation errors for starters. Even if it did compile, is it possible to do something like this?

Answer 1

If you want to store the lambda function you could do it like this for a void() function

std::function< void() > callback = [](){ dosomething };

Or, for a function with a return type and parameters,

std::function< int( int ) > callback = []( int i ){ return dosomething(i);}

You'll need to include this file to use std::function though.

#include <functional>