On Sat, Oct 11, 2008 at 5:51 AM, Andrew Farmer <[EMAIL PROTECTED]> wrote: > On 10 Oct 08, at 19:28, Ian Joyner wrote: >> >> So it's really a workaround for this situation. I think therefore there >> are several constructs to represent the same concept of "lack of presence" – >> nil, Nil, Null, and NSNull. > > Fewer than you think, actually. nil, Nil, and NULL are all internally > synonymous: the only difference is that nil and Nil have traditional > meanings in ObjC. (nil is (id) NULL, and Nil is (Class) NULL). NSNull is the > only odd case out - it's used in situations where a concrete object is > needed, such as in collections.
And just for the sake of accuracy, while this is conceptually correct, my installation of gcc expands all of them to ((void *)0). So at the low level they are interchangeable, but you should of course only use them in cases where they make semantic sense. Mike
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