On Mar 13, 2013, at 2:13 AM, Jean-Daniel Dupas <devli...@shadowlab.org> wrote: > Le 13 mars 2013 à 01:55, Wim Lewis <w...@omnigroup.com> a écrit : >> On 12 Mar 2013, at 2:08 AM, Graham Cox wrote: >>> in a + method, [self class] === self. Once you've got that, you've got it. >>> >>> >>> >>> You're overthinking this. >>> >>> A class method is just an instance method of the class object. No magic at >>> all. So all this confusion you've caused yourself about [super class] and >>> so on is wholly unnecessary to correctly use class methods. >> >> To be very slightly pedantic, the only magic here is 'super' --- sending a >> message to super (which you can only do from a method implementation) is >> special syntax that searches for the method starting with the >> implementation's class's superclass, rather than at the receiver's actual >> class. Everything else is non-magic. (In general, that's been one of the >> strengths of ObjC: very little magic.) >> > > To be ever more pedantic, there is other magic involved when sending a > message to a class. > If there is no class method that matches the selector, the runtime will then > search for instance methods of the root class.
Note that this isn't "magic" really; it's a quirk of the type system (both formal and dynamic). The root metaclass is a subclass of the root class. This can be problematic if you really want your root class to have a layout that's bigger than just an isa field, because the ABI and runtime just hardcode the layout of classes and there is no room for extra fields there — thus you need to be sure that anything using your extra fields is never invoked on a class object. John. _______________________________________________ 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: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
