a relic from the deepest darkest corners of c++

offset

template <typename T, typename F>
size_t offset(F T::* ptr)
{
    T* typePtr = (T*)nullptr;
    F* memberPtr = &(typePtr->*ptr);

    uintptr_t offset = (uintptr_t)memberPtr - (uintptr_t)typePtr;

    return offset;
}