Am 25.05.2008 um 09:41 schrieb Jens Alfke:
* Calling any method on a NULL object pointer doesn't crash, and doesn't call any code; instead, it's a no-op. This is actually extremely useful and can be taken advantage of to make your code much more concise by eliminating a lot of pointer checks.
One warning: For methods that have a return value, only certain return types are supported (which will in that case return 0). So read up on the details if you want to send a message to NIL.
* Method dispatch is more dynamic; it's based on the name of the method (the selector) not a vtable offset. This means that even if you don't know the class of an object at compile time, you can still call methods on it. For example, given a declaration "id foo", you can call [foo doSomething] and it will successfully call a method named doSomething, if foo has a base class that implements it, no matter what the class hierarchy looks like.
This is why ObjC supports "duck typing". Great tool in the tool belt. Cheers, -- Uli Kusterer "The Witnesses of TeachText are everywhere..." http://www.zathras.de _______________________________________________ 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]
