Re: [Gnumed-devel] Using queues to store parameters for parameterized functions put on wxCallAfter queue.

[catmat]

Karsten Hilbert wrote:

> > I think the bug was in using wxCallAfter.  I used wxCallAfter because I 
> > found changing the tree from within an event handler caused core dumps.
> >    
> Strange. That *should* work, one would suspect ...
>
>  
>
> > But the functions that have to be called from wxCallAfter need 
> > parameters,  so the solution
> > seemed to be  to queue the parameters as well.
> >    
> Nope. CallAfter takes arguments which it then passes to the
> first argument as arguments to that function call ... No need
> for queuing.
>
>  

You're right,
wxCallAfter does take arguments.

I tried not using wxCallAfter , and the error does occur.

>     
>     def start_edit_root_node(self, start_edit_text ):
>         """
>         this handles the problem of no event fired if label unchanged.
>         By detecting for the return key on the edit control, the start 
> text
>         can be compared, and if no change, the node is deleted
>         in the __key_down handler
>         """
>         root_node = self.get_emr_tree().GetRootItem()
>
>         #self.q_edit.put( (root_node, start_edit_text) )
>         self.start_edit_node(root_node, start_edit_text)



> Traceback (most recent call last):
>   File "/usr/lib/python2.3/site-packages/wx/_core.py", line 10588, in 
> <lambda>
>     lambda event: event.callable(*event.args, **event.kw) )
>   File "wxpython/gmEMRBrowser.py", line 391, in start_edit_node
>     wx.EVT_KEY_DOWN( self.edit_control,  self.__key_down)
>   File "/usr/lib/python2.3/site-packages/wx/_core.py", line 2753, in 
> __call__
>     self.Bind(target, id1, id2, func)
>   File "/usr/lib/python2.3/site-packages/wx/_core.py", line 2719, in Bind
>     target.Connect(id1, id2, et, function)
> AttributeError: 'NoneType' object has no attribute 'Connect'


> > Previously , the node was created outside of wxCallAfter, and the event 
> > handlers to delete it if it wasn't used during edit mode , was
> > added from within wxCallAfter. So rapid clicking could move the node 
> > from edit mode, to saved mode, before
> > the event handlers could be added later in wxCallAfter, and adding the 
> > event handlers when the node was already saved
> > with the default label was too late.
> >
> > Isn't that an interesting bug ? :-)
> >    
> Nice catch. But the solution should be far easier than
> explicitely using the Queue module (see above).
>
> Karsten
>  
It should, but it doesn't.  The ghost edit control on rapid clicking still
occurs.

It's a bit fortuituous I didn't know about the arguments for wxCallAfter().

> def start_edit_root_node(self, start_edit_text ):
>         """
>         this handles the problem of no event fired if label unchanged.
>         By detecting for the return key on the edit control, the start 
> text
>         can be compared, and if no change, the node is deleted
>         in the __key_down handler
>         """
>         root_node = self.get_emr_tree().GetRootItem()
>
>         #self.q_edit.put( (root_node, start_edit_text) )
>         wx.wxCallAfter(self.start_edit_node, root_node, start_edit_text)
>     

>         def start_edit_node( self,  node, start_edit_text):
>                 #node = None
>                 #while True:
>                 #       try:
>                 #               print "removed edit request"
>                 #               old_node = node
>                 #               (node, start_edit_text) = 
> self.q_edit.get_nowait()
>
>                 #               if not old_node is None:
>                 #                       print "request on old 
> root_node discarded : ", old_node, start_edit_text
>
>                 #       except Queue.Empty:
>                 #               break
>
>                 if not node is None:
>                         root_node = node
>                         node= 
> self.get_emr_tree().AppendItem(root_node, start_edit_text)
>                         self.get_emr_tree().EnsureVisible(node)
>                         self.get_emr_tree().EditLabel(node)
>                         self.edit_control = 
> self.get_emr_tree().GetEditControl()
>                         print self.edit_control
>                         self.start_edit_text = start_edit_text
>                         self.edit_node = node
>                         wx.EVT_KEY_DOWN( self.edit_control,  
> self.__key_down)
>                         wx.EVT_KILL_FOCUS(self.edit_control, 
> self.__kill_focus)
>                 else:
>                         print "No node was found"