> Le 10 août 2017 à 16:09, Charles Srstka <[email protected]> a écrit : > >> On Aug 10, 2017, at 8:59 AM, Alastair Houghton >> <[email protected]> wrote: >> >> On 10 Aug 2017, at 14:57, [email protected] >> <mailto:[email protected]> wrote: >>> >>> On Aug 10, 2017, at 02:18, Alastair Houghton <[email protected]> >>> wrote: >>>> >>>> Personally I *would* still discourage +new in favour of class-specific >>>> convenience constructors because I think it’s less expressive and also >>>> less consistent (e.g. +array is better, in my opinion, than +new, not >>>> least because +arrayWithObjects: and others exist). >>> >>> [NSArray new] := [[NSArray alloc]init] >>> >>> [NSArray array] := [[[NSArray alloc]init]autorelease] >>> >>> +array and friends came along with the introduction of autorelease pools, >>> to replace +new with something that didn't imply ownership (the oft >>> mentioned special meaning of "new" as prefix). So while with ARC they are >>> essentially equivalent, previously they were not. >> >> Yes, I know that, thanks. >> >> The point is, with ARC, they’re equivalent, and most new code uses ARC, so, >> again, I’d discourage +new in favour of class-specific convenience >> constructors. >> >> Kind regards, >> >> Alastair. > > They’re equivalent syntactically, but performance-wise, +array and friends > will cause the object to be put into an autorelease pool. Therefore, +new is > better for performance.
Putting an object into an autorelease pool is very cheap. It is just a write of the pointer value in a thread local array. When using ARC, the object is still pushed in the autoreleased stack, but it may be immediately pop by the caller. So yes, +array still have a couple of additional operations to perform, but it should be mesure to tell if this is significant performance wise. _______________________________________________ Cocoa-dev mailing list ([email protected]) 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 [email protected]
