Re: Confusing problems with inheritance in Objective-C
Re: Confusing problems with inheritance in Objective-C
- Subject: Re: Confusing problems with inheritance in Objective-C
- From: Chris Hanson <email@hidden>
- Date: Mon, 21 Jun 2004 21:12:52 -0700
On Jun 21, 2004, at 7:31 PM, Darren Ford wrote:
I've been programming in C++ for many years now, and I think the
problem is probably that I haven't fully understood the Obj-C concept
of inheritance and I'm trying to use my C++ knowledge to define my
class. Can anyone shed any light on why I'm seeing this problem?
I've attached my class definitions to the end of the email.
Another more general style critique on your code: You're creating a
subclass of NSMutableDictionary, but it looks like you're doing so just
to use a mutable dictionary rather than in order to create a new kind
of mutable dictionary.
In such a case, it's generally better to just have a mutable dictionary
that's referenced by an instance variable. That way you just have a
has-a relationship rather than an is-a relationship.
This goes any time you subclass another class, particularly a class
from a framework. The classic example is how I've seen some developers
immediately create a subclass of some other frameworks' window class
when setting up a new application. They aren't actually creating a new
kind of window (a round window, or a window that runs away from the
mouse) -- they're just putting stuff in the window. So they don't
actually need to create that subclass.
-- Chris
--
Chris Hanson <email@hidden>
http://www.livejournal.com/users/chanson/
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