Communicating between in and out contracts

[Rainer Deyke]

Andrei Alexandrescu wrote:
> Rainer Deyke wrote:
> The expression may mutate stuff.

It shouldn't.  It's an error if it does, just like it's an error for an
assertion or post/precondition to have any side effects.

It would be nice if the compiler could catch this error, but failing
that, 'old' expressions are still no worse than assertions in this respect.

> If you know about Eiffel's old, I'd appreciate if you explained how it
> works. I am arguing exactly because I don't know. My understanding is
> that neither of us currently knows how it works, so I don't think it's
> ok to refer me to Eiffel.

My suggestion to ask the Eiffel community directly was meant seriously.


-- 
Rainer Deyke - rainerd at eldwood.com