From: Jim Freeze <jim@...>
Date: 2002-12-15T00:38:41+09:00
Subject: Re: Is it wise to extend Matrix?

On Saturday, 14 December 2002 at 22:36:11 +0900, Gavin Sinclair wrote:
> Since the thread "Inheritance question" has become so deep (physically :) and
> my point is sort of orthoganal to it, new thread.
> 
> In Jim's case, he wanted to add some methods to Matrix.  Well, he didn't want
> to change Matrix directly, but the methods he was going to add would in no way
> be out of place in the real Matrix class, so to me, inheritance is the wrong
> approach.  Delegation is the key here.  Create a new class based on Matrix, add
> your methods, and forget that Matrix ever existed.
> 
> Of course, I think there are some implementation problems he had with the type
> that was returned from some methods - I lost track.  But maybe he can come up
> with a new kind of delegation that solves that.

Yes, that is what I want. The Matrix class has a sticky issue since it
uses a class method constructor. But, if I overlook that temporarily, I
think the delegator class would need the ability to wrap functions that
were chainable and return self.  I believe it is as simple as that. But
I have not come up with a good syntax for that and I don't think I have
had the 'ah-ha' moment about delegators yet.

-- 
Jim Freeze