Re: How to create to-many accessor methods at runtime
Re: How to create to-many accessor methods at runtime
- Subject: Re: How to create to-many accessor methods at runtime
- From: Mike Abdullah <email@hidden>
- Date: Tue, 8 Jul 2008 16:55:44 +0100
On 8 Jul 2008, at 15:45, Steve Weller wrote:
On Jul 8, 2008, at 2:28 AM, Mike Abdullah wrote:
On 8 Jul 2008, at 07:10, Steve Weller wrote:
What I am attempting to do is not working. -valueForKey: does not
look for methods with -respondsToSelector: to figure out if
methods exist sufficient to have KVC. So overriding this has no
effect. My only option, it seems, is to use +resolveInstanceMethod
and actually create the methods that are needed.
Or, you know, just override -valueForKey: ? NSArray and the other
contain classes do just that to get their custom behaviour.
Then I'd need to create an NSArray proxy, probably by subclassing
NSArray. This was the way I first thought of and decided not to go
that route.
My current thinking is to hard-code -count and -objectForKey (and
possibly others) in a helper object, then vend instances of that
according to what the array should implement. Each of those objects
ultimately gets its data from a single source, so if I change
values, all the arrays' customers see the changes. It is likely that
I will want KVO compliance one day too and that will not work with
the helpers.
Well I am now officially confused. As I understood it, you were
writing a class that could have any number of keys, each one of which
was a one-to-many relationship. Since the number of keys was
undefined, it wasn't possible to write accessor methods for them, and
so instead, you were overriding -respondsToSelector: and friends to
fool the KVC system into thinking that you had written the appropriate
accessor methods.
But, the implementation of -valueForKey: specifically does not use -
respondsToSelector:, and so you can't the fool the system that way.
And so, I'm suggesting simply overriding -valueForKey: in your custom
class in order for it to return a suitable array.
However, from your last mail, it seems I have the wrong end of the
stick, as you think it requires overriding -valueForKey: in a custom
NSArray subclass. So, um, any chance of some clarification?
Steve Weller email@hidden
Technical Writing, Editing, Developer Guides, and a little Cocoa
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