contract for mutableArrayValueForKey: ?
contract for mutableArrayValueForKey: ?
- Subject: contract for mutableArrayValueForKey: ?
- From: Jim Rankin <email@hidden>
- Date: Tue, 2 Dec 2003 19:12:48 -0500
What's the contract that mutableArrayValueForKey: expects objects to
implement? I'm getting the following exception:
2003-12-02 18:56:51.698 MarshallingTest[4234] *** Uncaught exception:
<NSInternalInconsistencyException> *** -[NSKeyValueSlowMutableArray
addObject:]: value for key types of object 0x509d80 is nil
when trying to add an object to the result of calling
mutableArrayValueForKeyPath: on an object whose interface includes the
following methods:
-(NSMutableArray *)types;
-(void)setTypes:(NSMutableArray *)value;
Now, types returns nil if setTypes: has not been called yet. But
according to the docs for mutableArrayValueForKey:
"2. Otherwise (no set of mutable array primitive methods is found),
searches the class of the receiver for an accessor method whose name
matches the pattern set<Key>:. If such a method is found, each
NSMutableArray message sent to the collection proxy object results in a
set<Key>: message being sent to the original receiver of
mutableArrayValueForKey:."
So doesn't that mean that the first time I add an object to the result
of mutableArrayValueForKey:, it should call setTypes: with an
NSMutableArray containing the object being added? If not, what does
this mean?
Lastly, what's the best way to work around this behavior, when I'm
calling mutableArrayValueForKey: on objects for which I don't have
access to the source? Do I need to check whether the value for the
key(path) returns nil before calling mutableArrayValueForKey(Path): ?
Thanks,
-jimbo
Excelsior! XML Marshaller for Cocoa
http://www.homepage.mac.com/jimbokun/Excelsior.html
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