Re: [rox-devel] [PATCH] ROX-Lib2 1.9.16: Menu.ToggleItem

[Thomas L. <ta...@ec...>]

On Tue, Oct 19, 2004 at 09:54:40AM -0700, Ken Hayber wrote:
> Thomas Leonard wrote:
> >On Sat, Oct 16, 2004 at 01:14:38PM -0700, Ken Hayber wrote:
> >
> >>Thomas,
> >>
> >>I noticed that using more than one ToggleItem in a menu didn't work.  The 
> >>update function of the _last_ item got called for _all_ items.
> >>
> >>The problem seems to be that the update_callbacks array stores the widget 
> >>on which to call the update, but this widget is not bound at the time it 
> >>goes into the array.  So all widget references are shared and end up 
> >>being the last widget in the loop.
[...]
> >A simpler change might be (untested):
> >
> >- self.update_callbacks.append(lambda: fn(self, widget))
> >+ self.update_callbacks.append(lambda w=widget: fn(self, w))
> >
> 
> No, at least not as written.  But I think I see what you were trying to do. 
> I think w is still just a reference to widget; 'w' is still changing when 
> 'widget' does.

No, my patch did fix the widget problem... but 'fn' had exactly the same
issue so it still didn't work ;-) Fixed now, and I've added a unittest to
check for it as well.

> It (w) really needs to be a copy(?) or a reference to the original widget, 
> not the variable 'widget' itself?  Some of the underlying python 
> implementation stuff is unclear to me.

In w=widget, 'widget' is looked up when the lamba is created and the thing
it points to is stored, to become 'w' when the function is invoked.

Thanks,


-- 
Dr Thomas Leonard		http://rox.sourceforge.net
tal at ecs.soton.ac.uk	        tal197 at users.sourceforge.net
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