Re: NSDictionary design bug (was: Re: Ugly bug in Foundation, beware!)
Re: NSDictionary design bug (was: Re: Ugly bug in Foundation, beware!)
- Subject: Re: NSDictionary design bug (was: Re: Ugly bug in Foundation, beware!)
- From: Nicko van Someren <email@hidden>
- Date: Mon, 7 Jun 2004 18:34:09 +0100
On 7 Jun 2004, at 18:21, Marcel Weiher wrote:
On 7 Jun 2004, at 18:06, Nicko van Someren wrote:
That depends on what you call easy. It's trivial to do if you use
a wrapper class like this (typed in Mail.app):
That's a wrapper class. Not subclassing. Next.
That's a wrapper class for the references, to be used by the subclass
of NSDictionary. It retains the pointer to the original object
across to copying of the wrapper object.
Once you have the wrapper, you don't need a NSDictionary subclass,
True, but if you DO subclass then you can make it otherwise transparent
to the user (e.g. not require the user to ever see the wrappers at
all).
and you cannot (easily) do it with a subclass without the wrapper.
You can however, quite straightforwardly build something that as far as
the user is concerned acts just exactly like an NSDictionary save for
the copying of the key objects that are passed in. By subclassing
NSDictionary you can (a) do it without having to re-implement the whole
dictionary functionality and (b) be able to pass the new objects in
wherever NSDictionary objects had been expected. Is this not the
functionality that you were after?
I have implemented 2-3 of these wrapper classes myself.
I'll resist the temptation to suggest that you should have designed it
better then, since if you'd done it right you would only have needed to
implement one of these :-)
Next!
Sounds like a good plan.
Nicko
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