On 8 Dec 2008, at 17:15, [EMAIL PROTECTED] wrote:
There are a number of posts detailing with the ethics of the issue
of determining an object's mutability.
eg: http://www.cocoabuilder.com/archive/message/cocoa/2004/7/7/111173
Does anyone have a current informed pragmatic opinion on how to deal
with the following example?
I am not trying to determine program flow by determining mutability,
merely trying to limit the number of self inflicted injuries.
The following never seems to assert, regardless of whether dict is
mutable or not.
NSAssert([dict isKindOfClass:[NSMutableDictionary class]], @"dict is
not mutable");
I know that it is my responsibility to remain aware of an object's
allocated class but sometimes I find myself wanting.
This is because NSDictionary is a class cluster. What happens behind
the scenes is that Cocoa has a hierarchy of:
NSCFDictionary : NSMutableDictionary : NSDictionary
You are being handed an NSCFDictionary object which Cocoa has set up
to be immutable internally. Try to use one of the mutable methods and
it will throw an exception, but testing the class inheritance will
suggest it is mutable.
Mike.
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