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Re: Mutability

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Re: Mutability

Subject: Re: Mutability
From: Peter Ammon <email@hidden>
Date: Tue, 20 Nov 2001 16:03:26 -0500

On Monday, November 19, 2001, at 01:07 PM, Norbert Heger wrote:

Fortunately we now have real immutable collection classes (in 10.0 all
collection classes were mutable). Copying an immutable instance now simply
retains and returns the very same object, and invoking a mutating method
raises an exception.

But be aware of the fact, that even if an instance is immutable, it will be
a subclass of a mutable (abstract) superclass. Thus invoking [array
isKindOfClass:[NSMutableArray class]] will NOT tell you if the given array
is in fact mutable. Instead it always returns YES.

[...]

Thanks for the heads up, I'm sure this would have bitten me sooner or later. So what's the proper way to determine if a collection is mutable or not, if we can't use isKindOfClass: ?

-Peter

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  - From: Vince DeMarco <email@hidden>

References:
	>Mutability (From: Norbert Heger <email@hidden>)

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