Re: isa
Re: isa
- Subject: Re: isa
- From: Ondra Cada <email@hidden>
- Date: Mon, 3 Jun 2002 13:41:04 +0200
On Monday, June 3, 2002, at 05:48 , Aram Greenman wrote:
However, if A' inherits from A, saying an A' is an instance of A _is_
correct, insofar as it has all the instance variables of A and therefore
possesses everything that makes an A an A.
Wrong again. Well, the properties would be there, but can be obsoleted in
A' -- not used anymore, the same functionality encapsulated into a
different set of properties altogether.
Or the algorithms may have changed: presume some views, where A draws
without special translations, A' uses them. Then any drawing- or
placemernt- related method on A level would draw improperly and/or return
improper positions (since it would ignore the translations).
There is an infinite number of similar possibilities, which make direct
calling a super-super-class' implementation a potential havoc of no small
order.
---
Ondra Cada
OCSoftware: email@hidden
http://www.ocs.cz
private email@hidden
http://www.ocs.cz/oc
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