[PyKDE] PyQt - getting unexpected async reply in threaded app (newbie)

[Phil Thompson]

On Saturday 22 February 2003 11:53 am, Nicholas John Murison wrote:
> Hi all,
>
> Both a colleague and I have run into the identical problem when using
> PyQt in a threaded environment.
>
> I have a threaded app, which uses QThreads for the threading model.  I
> am trying to get the child threads to be able to create and display
> windows as part of the GUI.  To my knowledge, all GUI creation must take
> place within one thread in PyQt.  Therefore I am trying to do all GUI
> calls from the main thread.  This isn't working, and I keep getting
> "unexpected async reply" errors from Xlib.
>
> Let me demonstrate my object instance hierarchy:
>
> __main__
>   -> creates a QApplication
>   -> creates a QObject derivative
>      -> creates QThread derivatives
>         -> creates SocketServer.TCPServer derivatives
>            -> creates SocketServer.BaseRequestHandler derivatives
> 	      -> calls main QObject derivative instance and asks for a
>                  window to be displayed
>
> This last step is where it all goes wrong.
>
> My classes are split over several files, a few of which need to import
> qt.  So the qt module is imported several times over, which hopefully is
> ok.
>
> Also, I tried referring to the global qApp object, both in my
> BaseRequestHandler derivative class, and in the main QObject derivative
> class in the main thread.  In both of these cases, Python claimed qApp
> did not exist.
>
> Any suggestions would be most helpful.

At the risk of stating the obvious, have you read the "Thread Support in Qt" 
section of the Qt documentation?

Phil