On Feb 16, 2014, at 10:22 AM, Kevin Meaney <k...@yvs.eu.com> wrote: > You're missing the question I was trying to ask. Why is autorelease needed at > all?
It's needed when a method creates an object [or otherwise gets an object with a reference that needs to be released] and has to return that object, but the caller isn't aware that the reference needs to be released. The method can call -autorelease on that object, which schedules a pending release in the future, balancing the ref-counting. You could argue that if ARC were mandatory [which it isn't, remember] autorelease wouldn't be necessary because the method above can be declared as returning a strong reference, so the caller will know to release it. Unfortunately it isn't that simple, because there can be multiple implementations of a method. For example, a class might implement a -bgColor method that returns an NSColor stored in an instance variable; so the return value doesn't need to be released. But a subclass might override -bgColor to allocate and return a new NSColor instance. Now the caller _does_ need to release it, but the caller doesn't know that because it has no idea which implementation of -bgColor actually got called. The only way to resolve this without autorelease would be to enforce that _all_ methods that return objects have to return a retained reference for the caller to release. This would end up adding a huge number of retain/release calls, which I'm pretty sure would affect performance. —Jens _______________________________________________ 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
