[PyQt] [PyKDE] KCrash, sometimes even glibc

Henrik Pauli henrik.pauli at gmail.com
Tue Aug 28 07:45:16 BST 2007

On Monday 27 August 2007, Phil Thompson wrote:
> Crashes on exit have two causes...
> - PyQt bugs related to object ownership
> - C++ objects being deleted in the wrong order (because Python objects are
> being garbage collected in a fairly random order).
> To debug these...
> - Always use current SIP and PyQt snapshots.
They're as new as possible.

> - Strip your application down to the bare minimum while still demonstrating
> the problem - I would expect no more than 100 lines.
This is really really tough.  Haven't got around to it yet.  But there must be 
something funky about the way I open windows.  There are a few things I 
could/should use Dialogs for instead of MainWindows, but for one, the 
friendlist window might get a menu bar at some point and that is something 
that in my eyes isn't a dialog :)  That aside, I don't think the two things 
are much different as far as widget ownership and closing them goes...  I 
found that setting WDestructiveClose destroys the C++ but not the Python 
object, which makes for a good deal of runtime errors.  If I don't WDC them, 
then I have to call .close() on the windows in the main window's queryClose() 
else we get stuck with hidden windows (apparently clicking the X button just 
hides these KMainWindows) and an app that's unable to exit.

Is there anything special I should be writing in __del__() or anywhere else?

Here's how I make the friendlist window from the event editor (happens when 
someone presses Ctrl+F):

  def editFriends(self):
    if not hasattr(self,"friendeditorWindow") or self.friendeditorWindow is 
      self.friendeditorWindow = 
ljkkdefriendeditor.LJKFriendEditor(self, "ljklient:friendeditor", 

and the queryClose stuff in eventeditor:

  def queryClose(self):
    if hasattr(self, "friendeditorWindow") and self.friendeditorWindow is not 
    if hasattr(self, "previewWindow") and self.previewWindow is not None:
    return True

  def queryExit(self):
    if app.ljConn.hasSession():
    return True

If this is right, then I guess it's something inside LJKFriendEditor that I'm 
doing very wrong.

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