Thank you, David.

Sounds like safety first for my code: always use the setter/getter for 
synthesized properties, even in self.

Or use ivars.

ScottB

On Oct 12, 2011, at 09:21 , Bayes Scott F wrote:

> Someone on Matt's site mentioned the possibility that the synthesized ivar 
> could be implemented indirectly, say as a member of a collection. Since the 
> implementation's opaque, we don't know if that ever can happen.
> 
> So, is self->mySynthIvar safe (both lvalue and rvalue), or should we be 
> messaging?
> 
> And does the compiler ever shortcut something like self.mySynthSimpleIntVar 
> to self->mySynthSimpleIntVar, or does it always use the setter/getter?
> 
> Thanks
> 
> 
> ScottB
> 
> On Oct 11, 2011, at 10:12 , David Duncan wrote:
> 
>> On Oct 11, 2011, at 9:57 AM, Matt Neuburg wrote:
>> 
>>> I did everything "right" when I named an ivar "firstResponder" (property, 
>>> synthesized ivar, synthesized accessors) and totally broke my app because 
>>> Apple was apparently already using an undocumented ivar called 
>>> "firstResponder".
>>> 
>>> http://www.cocoabuilder.com/archive/cocoa/296662-assign-property-behaves-differently-from-simple-instance-variable.html
>> 
>> The problem wasn't an undocumented ivar, it was an undocumented method. The 
>> @synthesize thus overrode the existing method and broke your project because 
>> parts of UIKit were expecting the default implementation and got your 
>> implementation instead.
>> 
>> As a rule, we strive to avoid this situation, but unfortunately this does 
>> happen on occasion.
>> 
>>> Also, note that there are circumstances where a synthesized ivar won't 
>>> work; see, for instance, this note:
>>> 
>>> http://www.cocoabuilder.com/archive/cocoa/298320-inherited-implicitly-created-member-is-no-member.html
>> 
>> The gist of this is that synthesized ivars are private, and the public 
>> interface (the @property) doesn't tell you about private implementation 
>> details (the ivar). As such, subclasses can't get at synthesized ivars, 
>> precisely because the @synthesize declaration is hidden from them.
>> --
>> 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/scottbayes-dev%40comcast.net
>> 
>> This email sent to scottbayes-...@comcast.net
> 
> _______________________________________________
> 
> 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/scottbayes-dev%40comcast.net
> 
> This email sent to scottbayes-...@comcast.net

_______________________________________________

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

Reply via email to