Re: [Rubycocoa-talk] Sporadic application failure

[Laurent S. <lsa...@ap...>]

On Dec 3, 2007, at 1:20 AM, Tim Burks wrote:

>
> Hi Tim,
>
> Your post reminded me of a problem that I recently had while working  
> with Nu.  So I ported your example to Nu and saw the same message.   
> I think the problem is in the PSMTabBarControl framework.  If you  
> look at PSMTabBarControl.m, you'll see this method:
>
> - (void)tabViewDidChangeNumberOfTabViewItems:(NSTabView *)aTabView
> {
>     NSArray *tabItems = [tabView tabViewItems];
>     // go through cells, remove any whose representedObjects are not  
> in [tabView tabViewItems]
>     NSEnumerator *e = [_cells objectEnumerator];
>     PSMTabBarCell *cell;
>     while(cell = [e nextObject]){
>         if(![tabItems containsObject:[cell representedObject]]){
>             [self removeTabForCell:cell];
>         }
>     }
>    ...
>
> This method is, in fact, mutating the _cells collection while it is  
> enumerating it.  I've heard that Leopard treats this more strictly,  
> so that might explain the exception.  I modified this method,  
> replacing the call that creates the object enumerator with this:
> [...]

Definitely, good catch!

FYI, the rationale behind this new exception is explained in http://developer.apple.com/releasenotes/Cocoa/Foundation.html 
  in the "Warning about mutations during enumerations" section.

Laurent