SFINAE compiler troubles

Question

The following code of mine should detect whether T has begin and end methods:

template 
struct is_contai         


        

Answer 1

This probably should be a comment, but I don't have enough points

@MSalters

Even though your is_container works (almost) and I've used your code myself, I've discovered two problems in it.

First is that type deque::iterator is detected as a container (in gcc-4.7). It seems that deque::iterator has begin/end members and const_iterator type defined.

2nd problem is that this code is invalid according to GCC devs. I qoute: values of default arguments are not part of the function type and do not take part in deduction. See GCC bug 51989

I am currently using this (C++11 only) for is_container:

template 
struct is_container {
    template <
        typename U,
        typename S = decltype (((U*)0)->size()),
        typename I = typename U::const_iterator
    >
    static char test(U* u);
    template  static long test(...);
    enum { value = sizeof test(0) == 1 };
};