enforce()?

[Jason Spencer]

I think about it roughly this way (in reverse priority):

Contracts/assertions concern problems in the program(ming) domain.

Exceptions concern problems in the system domain.

Problems in the actual problem domain should be modeled in the design
and have their own abstractions.

These interact a little bit, so I have an excuse to bend my rules
whenever I want :)  For instance, if the system is part of your
problem domain (e.g. embedded code), then exceptions are probably not
the right approach.  That's why I indicate a false idea of priority.

Jason