In a message dated Thu, 3 Oct 2002, Garrett Goebel writes: > Michael G Schwern: > > On Thu, Oct 03, 2002 at 05:30:49PM -0400, Trey Harris wrote: > > > In a message dated Thu, 3 Oct 2002, Michael G Schwern writes: > > > > > > > On Thu, Oct 03, 2002 at 03:59:08PM -0400, Mike Lambert wrote: > > > > > With pre/post conditions, a subclass is allowed to weaken the > > > > > preconditions or strengthen the postconditions. > > > > > > > > How exactly does one "weaken" a precondition? > > > > > > You weaken a precondition by adding ORs; you strengthen a > > postcondition by adding ANDs. > > > > As expressions in Perl run a tad beyond simple boolean logic, > > could you give a concrete example?
I don't know what you mean. How can a precondition be anything but boolean? > all inherited pre-conditions pass > or > class' own pre-conditions pass I'm afraid I'm a bit lost here. What does "pass" mean besides "evaluates to true in a boolean context"? And if that's what "pass" means, then can't you just OR the preconditions together, in subclass-to-superclass order? Trey
