On May 23, 2008, at 9:19 PM, Graham Cox wrote:
On 24 May 2008, at 7:34 am, Bill Bumgarner wrote:
The NSEnumerator stuff is prone to introducing silly errors, is
inefficient, and not very pleasant to look at.
Can you go into more detail about the efficiency improvements? I do
use a lot of NSEnumeration-based code and this *could* convince me
to use Obj-C 2.0 enumeration (though at present I'm still rather
keen to support Tiger). What sort of gains are we looking at? twice
as fast? ten times? Or 1.1 times?
I did some crude benchmarking a while back and found that
NSFastEnumeration was roughly the same as using
CFArrayGetValueAtIndex() in a loop, and both were faster than using
NSEnumerator or -[NSArray objectAtIndex:].
The significance of this depends on your situation, of course. In an
app that enumerates thousands of small collections while parsing a
file, dumping NSEnumerator in favor of CF functions was a big win in
terms of time and memory profiles in Shark, mainly because of the
overhead associated with creating/using/destroying lots of
enumerators. NSEnumerator also sends retain/autorelease to the last
object of its collection, so it can cause a pool to fill up if you're
not careful.
Here's an interesting graph, although a bit dated now:
http://www.mulle-kybernetik.com/forum/Optimization/viewtopic.php?t=27&sid=a6c5e357369c081eb672a8f604cdda98
This article has comparisons of Obj-C and CF overhead:
http://www.mulle-kybernetik.com/artikel/Optimization/opti-3-imp-deluxe.html
_______________________________________________
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 [EMAIL PROTECTED]
