I want to implement some sort of lookup table in C++ that will act as a cache. It is meant to emulate a piece of hardware I'm simulating.

The keys are non-integer, so I'm guessing a hash is in order. I have no intention of inventing the wheel so I intend to use stl::map for this (though suggestions for alternatives are welcome).

The question is, is there any way to limit the size of the hash to emulate the fact that my hardware is of finite size? I'd expect the hash's insert method to return an error message or throw an exception if the limit is reached.

If there is no such way, I'll simply check its size before trying to insert, but that seems like an inelegant way to do it.