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From: rad@aragorn.cm.deakin.oz.au (Robert Alan Dew)
Newsgroups: comp.lang.smalltalk
Subject: Re: Smalltalk Types
Message-ID: <7783@charlie.OZ>
Date: 4 Sep 89 12:12:21 GMT
References: <56930@aerospace.AERO.ORG> <7776@charlie.OZ> <6475@ux.cs.man.ac.uk>
Sender: root@charlie.OZ
Reply-To: rad@aragorn.UUCP (Robert Alan Dew)
Organization: Department of Computing & Mathematics - Deakin University
Lines: 23

In response to Alan Wills and William Cook where:

cook@hplabsz.HPL.HP.COM (William Cook) wrote
>NO!  NO!  NO!  Classes are *implementations*.  They often have type
>information mixed in with them (it is nice to know what type your
>implementation satisfies) but they are *not types*.

alan@ux.cs.man.ac.uk (Alan Wills) wrote
>Types *are* a useful concept for programming in any language, whether it
>has its own notation for them or not; and types aren't (necessarily) the
>same as classes.

I did not say types are classes.

I said, "Anyway, if you want to think about types then class is the analogy."

It seems that I was to abstract in my analogy.  When I wrote that 'types
are analogous to classes' I was thinking of something like:

	Class, Type := A description of a set of similar objects.


Robert Dew            rad@aragorn.cm.deakin.oz