On Saturday, 4 November 2017 at 15:38:42 UTC, Jonathan M Davis
wrote:
In principle, that would be nice, but in practice, it's not
really feasible. In the general case, there's no way to save
the state of the parameter at the beginning of the function
call (you could with some types, but for many types, you
couldn't). IIRC, it's been discussed quite a bit in the past,
and there are just too many problems with it.
It is obviously possible for a language that has been designed
for contracts. Whether it is practical is a matter of
optimization in my view…
Anyway, without having such a focus it makes little sense to say
that a language supports programming by contracts or pre/post
conditions. It is more of a syntactical construct in D. Although
class invariants are still useful in debugging.
C++ is getting pre/post conditions I think. Not sure if it will
be a plain syntactical construct like in D or something more
advanced.
