Why isn't std::string::max_size a compile-time constant?

Question

std::string provides a max_size() method to determine the maximum number of elements it can contain.

However, to work out the maximum lengt

Answer 1

This should also work:

enum : std::string::size_type {
    npos     = std::string::size_type(-1),
    max_size = npos - 1
};