C++ index of type during variadic template expansion

Question

I have a simple yet daunting problem I can\'t solve by myself. I have something like

template
T* create(SomeCastableType* args,         


        

Answer 1

Suppose SomeCastableType is castable to any type. Obviously what I can't get is that INDEX_OF_EXPANSION.

Since C++14, you can do the indices trick @Xeo mentioned with the support from the standard library, by using the std::make_index_sequence helper, as follows:

template
T* create(SomeCastableType* p, std::index_sequence)
{
    return new T(static_cast(p[Is])...);
}

template
T* create(SomeCastableType* p, std::size_t num_args)
{
    return create(p, std::make_index_sequence());
}