sakkinen@tukki.jyu.fi (Markku Sakkinen) (02/01/90)
This is connected with a criticism of Grogono and Bennett's paper "Polymorphism and Type Checking in Object-Oriented Languages" in the November 1989 issue of SIGPLAN Notices, specifically with their suggestion on handling alternative representations of complex numbers. I have read in some book or article an example in which a Complex object (implementing complex numbers) contained both the Cartesian and the polar representation and a validity indicator for each: at every moment, at least one representation must be valid, and even both can be. If memory serves, it was a well-done example. The only problem is that I don't remember where it was. My previous quest for a lost reference yielded very good results. I am again asking for some kind person who does remember where this example was presented, to mail me the exact reference. Thank you in advance! Markku Sakkinen Department of Computer Science University of Jyvaskyla (a's with umlauts) Seminaarinkatu 15 SF-40100 Jyvaskyla (umlauts again) Finland
sakkinen@tukki.jyu.fi (Markku Sakkinen) (02/02/90)
My question was answered immediately. (Why, I thought I had searched a bit for this example in my copy of OOSC before I lent it ...) From: wright@hsi.com (Gary Wright) Bertrand Meyer in Object-Oriented Software Construction on page 136 gives an example that seems to be what you are describing. Information confirmed by: From: Jacob Gore <jacob@blackbox.gore.com> From: Max Hailperin <max@Neon.Stanford.EDU> From: tynor@prism.gatech.edu (Steve Tynor) Thank you all (including those whose answer may be on its way)! Markku Sakkinen Department of Computer Science University of Jyvaskyla (a's with umlauts) Seminaarinkatu 15 SF-40100 Jyvaskyla (umlauts again) Finland
kim@helios.enea.se (Kim Wald`n) (02/03/90)
In article <2904@tukki.jyu.fi> sakkinen@tukki.jyu.fi (Markku Sakkinen) writes: > I have read in some book or article an example in which a Complex object > (implementing complex numbers) contained both the Cartesian > and the polar representation and a validity indicator for each: > at every moment, at least one representation must be valid, > and even both can be. If memory serves, it was a well-done example. > The only problem is that I don't remember where it was. You probably refer to the example in Bertrand Meyers "Object-Oriented Software Construction", pp. 136-139. -- Kim Walden Enea Data, Sweden kim@enea.se