Re: [Pyobjc-dev] signal 11 when trying to access an NSComboBox's data source

[Ronald O. <ous...@ci...>]

On Friday, 8 August, 2003, at 23:35, Steven D. Arnold wrote:

> Hi,
>
> I am writing a program which has a controller object with an  
> awakeFromNib
> function that begins like this:
>
>     def awakeFromNib( self ):
>         self.word_type.setDataSource_( WordTypeManager.alloc().init(  
> self.db
> ) )
>         print "will this fail?"
>         print "value = %s" % self.word_type.dataSource()
>         print "no, it worked"
>
> The program dies on a signal 11 on the line where it attempts to print  
> the
> data source.  We never see the "value =" text or the "no, it worked"  
> string.

Does it work any better when you assign the WorkTypeManager instance to  
an instance variable? As Martina already noted, the combobox probably  
doesn't retain it's datasource. There's not much we can do about that.  
Cocoa seems to do this quite often, probably to avoid reference  
counting cycles. Let's hope that Apple adds a real garbage collector in  
the future.

The documentations mentions this, but obviously not clearly enough.  
I'll try to improve the documentation.

BTW. Wouldn't it be possible to set the datasource within Interface  
builder, and use 'self.word_type.dataSource().setDB(self.db)' to finish  
initialising the datasource? That way you don't have to worry about  
reference counts at all.

>
> WordTypeManager is a class that is declared like this:
>
> class WordTypeManager( Foundation.NSObject,  
> AppKit.NSComboBoxDataSource,
> ListManager ):

BTW. You don't have to subclass from informal protocols anymore in  
1.0b1.

>
>     def init( self, db ):
>
>     def numberOfItemsInComboBox_( self, comboBox ):
>
>     def comboBox_objectValueForItemAtIndex_( self, comboBox, index ):
>
>     def comboBox_indexOfItemWithStringValue_( self, comboBox,  
> str_value ):
>
> I can provide more detail about the code if needed.
>
> I have verified that self.word_type is an NSComboBox and that the  
> class's
> outlet is connected to the right object in Interface Builder.
>
> I am using Python 2.3 (final) and PyObjC 1.0b1 (not CVS).  Note that I
> recently upgraded both Python and PyObjC, and the program worked fine  
> before
> this upgrade, although I last used the program a couple months ago.  I  
> am on
> Mac OS X 10.2.6, on a dual-processor 1 GHz machine.
>
> Any ideas what might be causing this problem?
>
> --  
> Steven D. Arnold                             st...@ne...
>      "One has a moral responsibility to disobey unjust laws."
>                         Martin Luther King
> News and Opinion Covering Free-Speech Issues in Media & Technology:
>             http://prime.neosynapse.net:8080/index.php
>
>
>
>
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