It's always driven me nuts that the base string in the STL is a fully mutable container that must manage it's own memory. I much prefer a string being either immutable, or an interface that you can implement however you see fit: a view over a raw buffer, a ref to a globally shared string instance that may or may not be ref counted, or like the STL, a version that self-manages its own memory.

Besides boost::string_ref, there is also a more generic flyweight implementation requiring only an equality concept for it's template parameter:

http://www.boost.org/doc/libs/1_56_0/libs/flyweight/doc/tuto...