One idea on the dynamically changing the global bounds for a type as I keep mentioning, one concern people have is that it could invalidate instantiated objects of the type. As I said before, being able to dynamically change the bounds at runtime is essential, but most of the time you would do it before you instantiate anything. Hence, one solution is to make a check to see if it has been instantiated yet. I don't know enough metaprogramming to know if this is possible, but the idea is to flip some kind of a compile time flag in the constructor of the type and if you try to change the bounds after that, it fails a compile time assertion. So, the following would work: typedef bounded_type interest_rate; interest_rate::change_bounds(.8, .99); interest_rate r = .95; But the following would fail at compile time: typedef bounded_type interest_rate; interest_rate r = .95; interest_rate::change_bounds(.8, .99); If this is a good idea, my only request is a preprocessor instruction to turn it off... -Jesse