Re: Silly and stupid post‑condition or not ?

["J-P. Rosen" <rosen@adalog.fr>]

Le 31/01/2012 00:11, Yannick Duchêne (Hibou57) a écrit :
> Is such a post‑condition a good or bad practice in your humble or
> authoritative opinion ?
> 
1) There is not stupid question

2) A precondition expresses what you require from the user of your
package. A postcondition is what you promise to the user. The important
point is that these conditions are part of the specification - visible.

Like any check (including simple constraints), conditions have no effect
whatsoever on a working program (presuming such a thing exists). It
helps during program development by having exceptions raised closer to
the cause of the problem, and work as kinds of lemma, intermediate steps
that help to make program proofs.

Is this particular one useful? If you think that it is a property of
your subprogram that should be made explicit to the user, yes. If you
think it is just a redundant property that only repeats the properties
of the specification, no. Really a matter of appreciation.

-- 
J-P. Rosen
Adalog
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