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Postings from January 2002
David Whipp writes: : Peter Haworth [mailto:pmh@edison.ioppublishing.com] wrote: : > This is all very sensible, and I completely agree with it. : > However, don't we : > need some restrictions on what can go in PRE and POST blocks : > to ensure that they are still valid in inherited methods? : : : There's another issue: sometimes we don't want to inherit PRE : conditions. DBC allows a derived method to strengthen (add) : post-conditions; but to weaken (remove) preconditions. I : haven't (yet) seen how this weakening would be accomplished. Damian told me you just handle that by ORing together the preconditions, but ANDing the postconditions. : Perhaps the mechanism that controls inheritance of : preconditions may have a more general applicability? Underneath it's all just block properties that happen to be closures. We can do whatever we want with them--as long as we agree on the definitions of "we" and "want". Or at least agree to disagree such that we keep out of each other's way. LarryThread Previous | Thread Next