On Wed, Jun 11, 2008 at 12:01 AM, John Engelhart <[EMAIL PROTECTED]> wrote: > > On Jun 10, 2008, at 11:28 AM, Charles Srstka wrote: >> >> I think the problem is that if NSArray has +[NSArray array] returning an >> NSArray, then NSMutableArray has to return an NSArray also, since it can't >> have a different method signature for the same method. As a result, if you >> called +[NSMutableArray array], the compiler would think you were getting a >> regular, non-mutable NSArray, and you'd get a warning if you tried to do >> this, although the code would still work: > > No, each class is allowed to define different types for the same method: > > http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC/Articles/chapter_9_section_2.html#//apple_ref/doc/uid/TP30001163-CH16-TPXREF161 > > This whole business about '(NSArray *) means NSArray AND any of it's > subclasses' is the result of sloppy thinking and confusing 'able to' with > 'as per spec'. > > If you declare a method prototype as '-(NSArray *)resultsArray', then you > have explicitly communicated that a NSArray is going to be returned. Not a > NSMutableArray. Not 'Jimmies groovy array with red pin stripes'.
This is simply not true. Returning (NSArray*) only means "I will return an object that you can assume is an NSArray". Not a single one of the convenience methods on NSArray actually return an NSArray, they all return one subclass or another. >A NSArray. Period. A NSMutableArray != a NSArray. No, All NSMutableArrays are also NSArrays, that is the very definition of subclassing. In any object-oriented system, subclassing establishes an "is-a" relationship between classes. > If you're going to be returning (or accepting) more than a single class, you > use id, which clearly communicates your intentions. Again, no. It is perfectly acceptable to pass an NSMutableArray where an NSArray is expected. -- Clark S. Cox III [EMAIL PROTECTED] _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
