On Sun, Apr 18, 2010 at 2:09 AM, Kyle Sluder <kyle.slu...@gmail.com> wrote: > On Sat, Apr 17, 2010 at 8:29 PM, Ben Haller > <bhcocoa...@sticksoftware.com> wrote: >> I don't think I'm crazy about this. There are many different subclasses, >> so each subclass would have its own corresponding struct, and every ivar >> access would go through an indirection; it sounds very confusing and messy. >> Not to say there might not be cases where it would be the correct design; >> but for my situation, I think I'm happier with my current design. Thanks >> for the suggestion, though! > > Dirty little secret: every ivar access on 64-bit is already indirected > through the runtime. Otherwise the runtime couldn't support > non-fragile instance variables. :) > > You could theoretically get better performance if your instance > variable were a pointer-to-struct. But if your way is sufficiently > performant, stick with it.
If by "indirected through the runtime" you mean "accesses one global variable to get an offset". It does not, as one might take your comment to indicate, actually call any runtime functions. Putting everything in a pointer to a struct won't be faster. You have to access an ivar anyway to get the pointer, and then you've added another dereference before you can get your data. In addition, you've hurt locality of reference, so will probably have worse cache performance characteristics. Mike _______________________________________________ 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
