Re: NSActionCell _control_view

[Fred Kiefer]

Rob Burns wrote:
> I'm having problems displaying an NSTableView. when I run my app, 
> sometimes it will behave as expected and display the contents of the 
> NSTableView. And other times it will segfault when displaying the first 
> item. This appears to be becuase the _control_view instance variable of 
> NSActionCell gets set to something other than the NSTableView, in which 
> the cell is being displayed. The gdb output thats attached shows this. 
> also in my program I can print this variable when ever a cell is drawn 
> by putting this:
>
>    NSLog(@"cell control view - %@", [[aCell controlView] description]);
>
> in
>
> - (void) tableView: (NSTableView *) aTableView
>     willDisplayCell: (id) aCell
>      forTableColumn: (NSTableColumn *) aTableColumn
>                 row: (int) rowIndex
>
> when the app functions correctly, a description of the NSTableView is 
> printed. When the _control_view variable has gotten set to something 
> else, it will sefgault on the NSLog. The program can be found here:

It did not segfault for me, but printed the following:

2003-12-29 11:57:56.052 Pimzler[3377] cell control view - 
<GSControlTemplate: 833c4b0>
2003-12-29 11:57:56.053 Pimzler[3377] cell control view - 
<GSControlTemplate: 833c4b0>

Looks like the Gorm prototype is still stored in the NSActionCell when 
you are about to display it. One easy fix for this could be not to 
encode/decode the control view with the NSActionCell. I am not sure why 
this gets stored at all.

On the other hand I also don't see, why your application should fail 
over this. Hmm, maybe the GSControlTemplate has by that time already 
been freed, as the control view is not retained and you are now 
referencing an invalid object. Yes, that might do.

I just tested with setting _control_view to nil in [NSActionCell 
initWithCoder:] and that would work. But we need more input on the side 
effects of this change or better solutions to it. Best you report this 
as a bug in the Savannah form, so it wont get lost.

Cheers
Fred