Re: ARC + CF types
On Mon, Aug 29, 2011 at 7:20 AM, Thomas Davie tom.da...@gmail.com wrote: I'm not really very clear on how ARC and CF types are meant to interact yet, because of that I've managed to create some buggy code, could someone have a quick stare at this and tell me what I've misunderstood that's causing a segfault when adding to the mutable set: https://gist.github.com/1178475 Does the implementation of those objects' -hash method agree with your definition of equality? (i.e. it is almost always wrong to change the concept of equality without also changing the hash implementation). -- Clark S. Cox III clarkc...@gmail.com ___ 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
Re: ARC + CF types
On 31 Aug 2011, at 21:55, Clark Cox wrote:
On Mon, Aug 29, 2011 at 7:20 AM, Thomas Davie tom.da...@gmail.com wrote:
I'm not really very clear on how ARC and CF types are meant to interact yet,
because of that I've managed to create some buggy code, could someone have a
quick stare at this and tell me what I've misunderstood that's causing a
segfault when adding to the mutable set:
https://gist.github.com/1178475
Does the implementation of those objects' -hash method agree with your
definition of equality? (i.e. it is almost always wrong to change the
concept of equality without also changing the hash implementation).
The only change in the equality concept is that isEqualToAPIObject: assumes
that it's been given an APIObject and doesn't check that the other object is
the right class. Otherwise the equality semantics are identical.
if (*ra4 != 0xffc78948) { return false; }
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ARC + CF types
I'm not really very clear on how ARC and CF types are meant to interact yet,
because of that I've managed to create some buggy code, could someone have a
quick stare at this and tell me what I've misunderstood that's causing a
segfault when adding to the mutable set:
https://gist.github.com/1178475
Thanks
Tom Davie
if (*ra4 != 0xffc78948) { return false; }
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Re: ARC + CF types
On Aug 29, 2011, at 7:20 AM, Thomas Davie wrote: I'm not really very clear on how ARC and CF types are meant to interact yet, because of that I've managed to create some buggy code, could someone have a quick stare at this and tell me what I've misunderstood that's causing a segfault when adding to the mutable set: Given id foo and CFTypeRef bar: // assign bar to foo without making any implicit change to bar – traditional toll free bridging foo = (__bridge id)bar; // consume bar to create an ARC managed reference in foo – replaces foo = (id)bar; [foo release]; foo = (__bridge_transfer id)bar; // retain foo and manage it as a non-ARC reference – replaces bar = (CFTypeRef)[foo retain]; bar = (__bridge_retain CFTypeRef)foo; -- David Duncan ___ 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
Re: ARC + CF types
Thomas,
Why not use a NSMutableSet and avoid the bridging casts entirely?
davez
On Aug 29, 2011, at 7:20 AM, Thomas Davie wrote:
I'm not really very clear on how ARC and CF types are meant to interact yet,
because of that I've managed to create some buggy code, could someone have a
quick stare at this and tell me what I've misunderstood that's causing a
segfault when adding to the mutable set:
https://gist.github.com/1178475
Thanks
Tom Davie
if (*ra4 != 0xffc78948) { return false; }
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Re: ARC + CF types
Because NSMutableSet does not have the ability to specify a different version
of equality – though as Mike Ash pointed out in #macdev, NSHashTable may well
be appropriate.
Thanks
Thomas
if (*ra4 != 0xffc78948) { return false; }
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Re: ARC + CF types
Or, your code could subclass NSMutableSet and interpose the methods that add to
the set. In other words, mentally separate objects that are equal from
objects that should be in the set. The former is an equality check, the
latter is a policy decision.
davez
On Aug 29, 2011, at 7:37 AM, Thomas Davie wrote:
Because NSMutableSet does not have the ability to specify a different version
of equality – though as Mike Ash pointed out in #macdev, NSHashTable may well
be appropriate.
Thanks
Thomas
if (*ra4 != 0xffc78948) { return false; }
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Re: ARC + CF types
Doing that wouldn't magically use the more efficient equality check though
without recoding NSMutableSet almost entirely, or… you know, using
CFMutableSetRef and providing your own equality function.
Thanks
Tom Davie
if (*ra4 != 0xffc78948) { return false; }
On 29 Aug 2011, at 17:43, Dave Zarzycki wrote:
Or, your code could subclass NSMutableSet and interpose the methods that add
to the set. In other words, mentally separate objects that are equal from
objects that should be in the set. The former is an equality check, the
latter is a policy decision.
davez
On Aug 29, 2011, at 7:37 AM, Thomas Davie wrote:
Because NSMutableSet does not have the ability to specify a different
version of equality – though as Mike Ash pointed out in #macdev, NSHashTable
may well be appropriate.
Thanks
Thomas
if (*ra4 != 0xffc78948) { return false; }
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Re: ARC + CF types
On Aug 29, 2011, at 9:43 AM, Dave Zarzycki wrote: Or, your code could subclass NSMutableSet and interpose the methods that add to the set. In other words, mentally separate objects that are equal from objects that should be in the set. The former is an equality check, the latter is a policy decision. Note that NSMutableSet is a class cluster. Class NSMutableSet itself does not implement any storage. If you want to subclass NSMutableSet, you'll need to implement the storage and all of the core methods from NSSet and NSMutableSet yourself. Note that NSSet and NSMutableSet define set member equality as -isEqual:. Violating that in a subclass may break other code. -- Greg Parker gpar...@apple.com Runtime Wrangler ___ 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
