On Jan 6, 2011, at 12:17 PM, Jonathon Kuo wrote: > > On Jan 5, 2011, at 12:41 PM, Dave Keck wrote: > >>> Q: When a context object is set with dispatch_set_context(), is it >>> retained? Or do I need to retain it first, set it, and then in the cancel >>> handler release it? >> >> The 'context' argument is not retained. You can infer this primarily >> by the declaration of dispatch_set_context(), and also the mention >> that 'context' is "client defined" in dispatch/object.h; since the >> 'context' argument is an untyped pointer (void *), >> dispatch_set_context() cannot assume anything about the supplied >> 'context' argument, much less that it's a valid libdispatch object. >> > So I can supply anything here and GCD stores it _by value_, whether its a > simple integer or even a object pointer?
Yes, that is the nature of void *. Nothing can be known about a void * other than the value – therefore you can store anything there (even non-pointers as long as they are <= sizeof(void *)). Note, the finalizer passed to dispatch_set_finalizer_f() will not be called if the value is zero. davez_______________________________________________ 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 arch...@mail-archive.com
