On Thu, Feb 21, 2008 at 10:57 AM, Mike R. Manzano <[EMAIL PROTECTED]> wrote: > I know about the pattern to shut the compiler up: create a category on > NSObject with the method defined, but if I were to do that, wouldn't > respondsToSelector: always return YES for that method, defeating the > point of calling respondsToSelector: in the first place?
You're not just "shutting the compiler up", you're telling it the signature of the method you're trying to invoke. If the compiler hasn't seen the method declaration while it's compiling a compilation unit, it can't know what arguments it takes or what return type it gives, so it assumes a signature of the form -(id)methodName:... . This is why the compiler won't complain about unknown method signatures if, say, your class has a method -(void)doFoo but you send doFoo to an object of a distinct type; the compiler just uses the signature for -doFoo it already knows about, assuming that the one the receiver implements matches. You get a runtime exception if it doesn't. -respondsToSelector: only returns YES for methods that have actually been implemented. That's why the informal protocol pattern used in Cocoa works. --Kyle Sluder _______________________________________________ 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]
