The need to pass different types in the initialization_list

Question

I'm looking for a template based way to pass arbitrary number of params in the initialization_list(s).

Something like:

func({0, 1}, {0, 2.0f}, {0, "boo"}, ...);

or

func({{0, 1}, {0, 2.0f}, {0, "boo", ...}});

In the same time I want to be able to check the type of the second param in each (inner) brace. Maybe get sizeof(T) maybe do some if constexpr(std::is_same<T, ...>::value) match.

Is it possible? If so how would func() definition look like?

Answer 1

Make f take std::initializer_list<std::pair<std::any, std::any> >:

void f(std::initializer_list<std::pair<std::any, std::any> > il) {
    for (auto it = il.begin(); it != il.end(); ++it) {
        const std::type_info& type1 = it->first.type();
        const std::type_info& type2 = it->second.type();
        if (type1 == typeid(int)) {
            int val1 = std::any_cast<int>(it->first);
        }
        // ...
    }
}

If you have only a couple possible types, you can use std::variant<int, float, /*e.g.; etc. */> instead of std::any.