Re: [Pyobjc-dev] the mysterious attribute error

[Burris T. E. <bu...@gi...>]

Another clue:

*** malloc[5538]: error for object 0x5b9f00: Double free

Somewhere, memory management is going awry.

burris

On Mar 27, 2004, at 11:24 PM, Ronald Oussoren wrote:

>
> On 28-mrt-04, at 4:11, Burris T. Ewell wrote:
>
>> Okay, I've removed all of the threads from my application.  It's  
>> completely kosher.  I use NSTasks for the workers, and DO for  
>> callbacks.  It works just fine most of the time.  When I click around  
>> between rows, especially when one or more rows are getting frequent  
>> updates, I get the weird crash with the disappearing attribute when  
>> the cell is redrawing.  A race condition that causes objects to get  
>> decref'd?
>
> From Subclassing NSCell at  
> http://developer.apple.com/documentation/Cocoa/Conceptual/ControlCell/ 
> index.html#//apple_ref/doc/uid/10000015i:
>
> <quote>
> If the subclass contains instance variables that hold pointers to  
> objects, consider overriding copyWithZone: to duplicate the objects.  
> The default version copies only pointers to the objects.
> </quote>
>
> You should implemented copyWithZone: unless you subclass has  
> '__slots__ = ()', otherwise the copy of a cell will share its __dict__  
> with the original, without updating the reference count. That will  
> give problems later on.
>
> Ronald
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