[PyQt] Weird behaviour of destroyed() slots

[Giovanni Bajo]

On Sat, 2008-07-26 at 17:10 +0100, Phil Thompson wrote:
> On Wed, 23 Jul 2008 15:42:18 +0200, Giovanni Bajo <rasky at develer.com>
> wrote:
> > Hi Phil:
> > 
> >
> =============================================================================
> > import sip
> > from PyQt4.Qt import *
> > 
> > called = []
> > 
> > class Core(QObject):
> >      def __init__(self, parent=None):
> >          QWidget.__init__(self, parent)
> >          QObject.connect(self, SIGNAL("destroyed()"), self.callback)
> >          QObject.connect(self, SIGNAL("destroyed()"), lambda: 
> > self.callback())
> >      def callback(self):
> >          called.append("done")
> > 
> > app = QApplication([])
> > core = Core(app)
> > sip.delete(core)
> > 
> > assert len(called) == 2, called
> >
> =============================================================================
> > Traceback (most recent call last):
> >    File "bugpyqt.py", line 18, in <module>
> >      assert len(called) == 2, called
> > AssertionError: ['done']
> > 
> > The slot with "lambda" is called, but the other one is not.
> 
> The reason is that PyQt knows that self is being destroyed and
> self.callback may be a wrapped C++ method (although it isn't in this case)
> so it won't invoke it.

Why does it refuse to invoke a wrapped C++ method? Even if self is being
destroyed (that is: within its C++ destructor) is still valid to invoke
methods AFAICT. After all, it's something that's perfectly doable in C++
as well. Or not?
-- 
Giovanni Bajo
Develer S.r.l.
http://www.develer.com