Can I create anonymous classes in C++ and capture the outside variables like in Java?

Question

In Java, when I need a callback function, I have to implement an anonymous class. Inside the anonymous class, I can access the outside variables if they\'re final

Answer 1

You can capture the variable manually (which is similar to what a lambda capture does behind the scenes):

int main() {
    int y = 100;
    struct { 
        int& y;
        int operator()(int x) { return x + y; }
    } anon = { y };
}

You can then use it like this:

#include 
...
std::cout << anon(10) << std::endl;

Prints 110 as expected. Unfortunately you can't have the anonymous type inherit from another with this method as initializer-list constructable types can't inherit from another type. If inheritance is crucial then you should use the constructor method outlined by Andy Prowl.