Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!samsung!munnari.oz.au!metro!ipso!runxtsa!timm From: timm@runxtsa.runx.oz.au (Tim Menzies) Newsgroups: comp.object Subject: Re: Do we really need types in OOPL's? Message-ID: <2547@runxtsa.runx.oz.au> Date: 8 Nov 90 23:09:56 GMT References: <1990Oct19.180646.8649@ux1.cso.uiuc.edu> <45940@apple.Apple.COM> Distribution: comp Organization: RUNX Unix Timeshare. Sydney, Australia. Lines: 28 In article bevan@cs.man.ac.uk (Stephen J Bevan) writes: >In article <45940@apple.Apple.COM> lins@Apple.COM (Chuck Lins) writes : [a lot of stuff about type checking reducing program errors] I've posted previously re the myth of "type checking finds all you errors". As a case in point, right now I'm debugging a highly interactive environment written in Smalltalk V/286. It is interesting to note that the sort of errors I'm getting aren't type errors. Rather, the majority of my time is taken up with state transitition errors. I've been a good OO programmer and decentralised the control amongst all my independent objects. Each object gets its own window and the user is free to leap around from window to window doing whatever feels best for them at the time. Now, my current set of errors are to do with things like "this happens after that which updates varibale X inappropriately becuase that-thing-over-there hasn't happend first." I.E. "type" is not a problem in this appliction right now. "Time" is. If someone can tell me how software can automatically check for these sorts of runtime errors, I'd be most interested. I suspect the rigourous answer is something like the Eiffel assertion mechanism. -- _--_|\ Tim Menzies (timm@runxtsa.oz) "Its amazing how much 'mature / \ HiSoft Expert Systems Group, wisdom' resembles being too \_.--._/ 2-6 Orion Rd Lane Cove, NSW, 2d066 tired." - Lazarus Long v 02 9297729(voice),61 2 4280200(fax) (a.k.a. Bob Heinlein)