[python-win32] (no subject)

[Alex Denham]

Thanks mike, i was thinking of doing something along those lines using the os modules tmpfile() method.
Althought i'm pretty i can post custom events to the Tkinter event loop, will try that first.

Thanks

> Date: Mon, 28 Apr 2008 08:33:50 -0500
> From: mdriscoll at co.marshall.ia.us
> To: a1eio at hotmail.com; python-win32 at python.org
> Subject: Re: [python-win32] (no subject)
> 
> Alex Denham wrote:
> > Hi all,
> >
> > I'm just wondering but when i try to access/update anything on my 
> > Tkinter GUI from one particular function, my whole program 
> > crashes/freezes with no error.
> >
> > The function is part of a class which handles all the GUI 
> > drawing/event handling etc.
> > The function in question gets called from a win32 DesignatedWrapPolicy 
> > class. Sample code below:
> >
> > [code]
> >     # this function is part of an IDropTarget class, the TargetWidget 
> > was definined in the __init__ method of this functoin and it points to 
> > my class which handles the GUI.
> >     def Drop(self, data_object, key_state, point, effect):
> >         data = data_object.GetData((15, None, 1, -1, 1))
> >         print data
> >         n_files = shell.DragQueryFileW(data.data_handle, -1)
> >         print n_files
> >         filenames = [shell.DragQueryFileW(data.data_handle, n_file) 
> > for n_file in range(n_files)]
> >         print filenames
> >         self.TargetWidget.filesDropped(filenames) # this calls the 
> > filesDropped function of the TargetWidget class and passes the 
> > filename list to it.
> >
> >     # this function is part of the GUI class (which inherits from 
> > Tkinter.Toplevel) the print commands work however if i uncomment the 
> > clearInput function (which just calls self.filepathInput.delete(0, 
> > END) to clear the text)
> >     # the program hangs, same for the second commented line, and 
> > anything else that requires a call to tk it appears. Is there some 
> > sort of conflict going on between win32 and Tk ??
> >     def filesDropped(self, fileList):
> >         print fileList
> > #        self.clearInput()
> > #        self.filepathInput.insert(Tkinter.END, fileList[0])
> > [/code]
> >
> > I'm just wondering if there's something i need to do to 'release' the GUI?
> > I'm pretty sure it's got nothing to do with my code elsewhere because 
> > it was all working smoothly before, and if i call the filesDropped 
> > function from somewhere else (not from the IDropTarget class) i don't 
> > have any issues.
> >
> > Thanks in advance,
> > Alex
> This is just a guess, but you usually cannot update a GUI from an 
> outside process directly. At least, this is true of wxPython. I think 
> your blocking the idle event in Tkinter, which causes it to hang and 
> then when you try to update it, Tkinter crashes because you're making a 
> call on it from what amounts to a separate thread.
> 
> Instead, you ought to write to a file or post an event when the win32 
> part is finished that the Tkinter GUI can check periodically and then 
> react. In other words, have the win32 portion of your code write 
> something to a file and have Tkinter check the file every few seconds 
> and then update itself when it finds something in there.
> 
> In wxPython there is a way to subscribe to special events using the 
> PubSub module. Tkinter probably has its own nomenclature. If you can't 
> figure it out, I'd recommend the Tkinter mailing list.
> 
> Mike

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