enforce()?

[bearophile]

Norbert Nemec:
> [...] to place code for input contract checking in the *calling* code. [...]
> Output contract checks, on the other hand should be compiled inside the 
> returning routine.

Is this a positive thing to do? Can this be done? (D must support separate compilation, but in many situations this is not done/necessary, so maybe in such situations it can be done). Is Eiffel doing it? if it's a good thing and it's doable then what kind of changes does it require to the compiler?

Bye,
bearophile