Advice on a better way to extend C++ STL container with user-defined methods

Question

I inherited from C++ STL container and add my own methods to it. The rationale was such that to the clients, it will look act a regular list, yet has application-specific me

Answer 1

I can't see why you need to extend vector with those methods. You could just write them as standalone functions, eg:

int MaxA(const std::vector& vec) {
    if(vec.empty()) {
        throw;
    }

    int maxA = vec[0].a;
    for(std::vector::const_iterator i = vec.begin(); i != vec.end(); ++i) {
        if(i->a > maxA) {
            maxA = i->a;
        }
    }
    return maxA;
}

Or there's std::max_element which would do much the same... minus the throwing of course.