On Mar 11, 2013, at 1:55 PM, Dave <d...@looktowindward.com> wrote: > Not sure I understand: > > if from an Instance - Method, I do: > > [super someMehod]; > > It calls -someMehod in the superclass. > > if from an instance + Method I do: > > [super someMethod], then surely it's an error because this isn't an instance?
A class is an object. Inside a class method, `self` is a class object, and [super someMethod] sends a message to that class object, searching for a class method implemented by some superclass. (If a class is an object, then the class object must be an instance of some other class, right? Right: http://sealiesoftware.com/blog/archive/2009/04/14/objc_explain_Classes_and_metaclasses.html ) > So from a + method, what do: > > [super someMethod]; and > [[self superclass] someMethod]; These are similar but not identical. In your [NewClass newDict] example: * [super newDict] calls +[BaseClass newDict]. * [[self superclass] newDict] also calls +[BaseClass newDict]. The difference is which object the message is sent to. * [super newDict] calls +[BaseClass newDict], and inside that method `self` is the class object NewClass. * [[self superclass] newDict] calls +[BaseClass newDict], and inside that method `self` is the class object BaseClass. (Because that's what the [self superclass] returned). The [[self superclass] newDict] version is inferior for various reasons. It will do unexpected things in some circumstances (for example, if NewClass itself has a subclass). It's more code to type, and runs slower, and can bypass some of the compiler's type checking. You should use [super newDict]. -- Greg Parker gpar...@apple.com Runtime Wrangler _______________________________________________ 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
