Path: utzoo!attcan!uunet!bu.edu!snorkelwacker!apple!apple.com!rmh
From: rmh@apple.com (Rick Holzgrafe)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Multiple Inheritance -- Is It A Luxury?
Message-ID: <9093@goofy.Apple.COM>
Date: 11 Jul 90 21:07:40 GMT
Sender: usenet@Apple.COM
Organization: Apple Computer, Inc.
Lines: 32
References:<8967@goofy.Apple.COM> <8968@goofy.Apple.COM> <5991@amiga.UUCP>

In article <5991@amiga.UUCP> jimm@amiga.UUCP (Jim Mackraz) writes:
> (Rick Holzgrafe) writes:
> )Well, I like source too. But one of the best features of OOP is 
re-usable 
> )modules *without* having to hack the source.
> 
> Traditionally?  I thought part of Smalltalk was the browsing of class 
source
> code, changing it as needed.
> 
> I think it's pretty clear that you can't extend a class by inheritance
> in ways that were not anticipated by the author of the class.  If the
> "method" hooks you can override aren't in the right places, you are 
stuck.

You're right, and it's why I said "I like source too". It's not easy to 
write a class so that all reasonable extensions can easily be made by 
subclassing. (I know; I've tried.)

But that's the *goal* of OOP (well, one of them anyway :-). Easily 
sub-classable classes increase the productivity of the developers who use 
them.

Try hard to write classes whose users won't need source. Then give them 
source anyway.

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Rick Holzgrafe              |    {sun,voder,nsc,mtxinu,dual}!apple!rmh
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