Enable std::get support on class

Question

What are the templates that I have to specialize to support std::get?

struct MyClass {
  int a;
};

template 
struct MyContainer {
  MyClas         


        

Answer 1

I'm guessing you want to implement some algorithms that need access to arbitrary array-like containers using compile-time indices and therefor aim to use some function (like std::get) to uniformly perform that task?! In that case, it is the same business as making begin and end available for your class. You simply declare a function get in the namespace you declared your container class in, and let ADL do its jobs.

    template 
    MyClass& get (MyContainer& c) { return c.array[I]; }

    template 
    MyClass const& get (MyContainer const& c) { return c.array[I]; }

In your algorithm you just use get (without the std namespace prefix) and ADL will call the correct function. So, for the standard structures like array, tuple and pair std::get is invoked and for your container the get function that you provided.

    int main(){
        std::array a {{0,1,2}};
        auto t = std::make_tuple(0.0, 1.0f, 2);
        auto p = std::make_pair('0', 4.4);
        MyContainer<3> c;

        std::cout << get<1>(a) << std::endl;
        std::cout << get<1>(t) << std::endl;
        std::cout << get<1>(p) << std::endl;
        std::cout << get<1>(c).a << std::endl;

        return 0;
    }

Example