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From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Newsgroups: comp.object
Subject: Re: Inheritence and Delegation
Message-ID: <1266@skye.ed.ac.uk>
Date: 20 Oct 89 19:12:19 GMT
References: <125984@sun.Eng.Sun.COM> <135300006@p.cs.uiuc.edu>
Reply-To: jeff@aiai.UUCP (Jeff Dalton)
Organization: AIAI, University of Edinburgh, Scotland
Lines: 20

In article <135300006@p.cs.uiuc.edu> johnson@p.cs.uiuc.edu writes:
>>Delagation reflects reality better than inheritance:  your car does not
>>inherit from door, tire, and engine: is is a composite made up of
>>doors, tires, and an engine.  The fact that the window on the left door
>>is open should have no bearing on the state of other windows or the
>>fuel injection or tire pressure.
>
>Ack! BLechttt!   This is evidence of the dread disease of Flavors!
>This bears NO relationship to real inheritance at all.  Inheritance
>is supposed to be the IS-A relationship, but a Car is not a Door.
>A door is a component of a car, it is not a superclass of Car.

Real inheritance?  NO relationship?  This is just ideology talking.
Inheritance doesn't have ot be IS-A at all.  If that's the attitude
people are going to take, I'll choose delegation over "real
inheritance" any day.

BTW, Flavors doesn't say: inherit from parts; it says inherit
capabilities.  (IMHO).  I don't like cars inheriting from doors
either.