Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!NORUNIX.BITNET!knut-skog%rglab.uit.uninett
From: knut-skog%rglab.uit.uninett@NORUNIX.BITNET (Knut Skog)
Newsgroups: comp.windows.news
Subject: Class vars or Instance vars
Message-ID: <101*knut-skog@rglab.uit.uninett>
Date: 14 Mar 89 08:04:44 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 35


Thanks to Cris (cws) and Greg @Sun for instructive comments.


Gregs comment:

> Now, LiteWindow has not made all the right
> choices (by a long mark), so some of them can not be explained.

removes my first source of confusion.

Yes, I  too thought that instance-vars was non-shared and class-vars
was shared by all instances,  however Chris'  comment on composit objects
as instance vars gave me a new understanding of the term non-shared.
Is it right to state that class vars are shared and so is instance vars
that are  composite (string, array, dict, proc). Only the instance-vars that
are simple objects are non-shared.

To me this looks like a small problem. In object oriented system design
a class should be constructed based on the true nature of the attributes
of the objects under consideration. Class variations should be taken care
of by subclassing and truly private data of a class instance should be
defined as instance vars. The fact that class-vars is  'turned into
instance vars' (placed in Instance dict) as soon as their attributs are
assigned dynamicaly and therby makes it preferable to write 'natural
instance attributes' as class-vars, is a pecullarity of this system that
class-writers must be aware of. Right?

In my 25-years as computer professional I have never had a more
enjoyable and interesting  experiance than NeWS.
krg,

Knut Skog
Comp SC. Dep
Univ. of Tromsoe, Norway