Possible boost addition: sub string and const string.

Hello everyone. I have two classes which I found pretty handy: sub_string (behaves as a mirror of the portion of master basic_string) and const_string (C- string wrapper). Nice thing about these two is they implemented as template specialization of basic_string which has advantages: a) familiar interface; b) possibility to reuse the code written for basic_string (like string streams, lexical casts, etc). Any interest? Regards. Alexei Novakov