[PyQt] BUG: sip instance attribute error: Re: [eric4] python qscintilla traceback with current snapshot also

[Hans-Peter Jansen]

On Thursday 03 February 2011, 11:02:32 Phil Thompson wrote:
> On Thu, 3 Feb 2011 00:42:05 +0100, "Hans-Peter Jansen"
> <hpj at urpla.net>
>
> > Other than that, I'm pretty baffled at the moment. How could I
> > debug this issue any further? If I'm going to try bisecting it,
> > would you think, that rebuilding sip is sufficient (supposed, that
> > 4.12 will not be affected, and hence the issue won't cross library
> > version changes)?
> >
> > Begging-for-ideas-ly-yours,
> > Pete
>
> As your test case is so simple, and that the only bug reports I've
> had for either SIP or PyQt are a couple related to pyuic, it suggests
> that the problem is the way you are building them.

The build system is fully documented (OBS, you remember), and didn't 
changed since month. I don't play any really dirty games there. Two  
patches are applied (inherited from openSUSE builds, where they're used 
since ages): 
 * disable RPATH 
 * disable timestamping sip generated files

The former is not needed and the latter is used by the build system to 
detect real changes to built packages: if they don't differ, they're 
quashed (in order to avoid too much churn, aka build storms). You might 
remember, that I asked you for a global persistent flag in sip to 
disable it generally: that would spare us the second patch.

Since the OBS creates a defined build environment that only contains the 
defined build dependencies every time a package is build, this reduces 
the risk of misdirected side effects during build significantly. 

Using a package manager for the resulting packages eliminates the usual 
caveats of having stray builds lying around, dependency issues, and the 
like. All in all, it's a pretty robust "production grade" setup, that 
is also used to produce full distributions.


Back to the issue. Still no bisection, but a few more data points:
 * it doesn't appear for basic Qt types like QDate
 * it's not related to QScintilla


from PyQt4 import QtCore, QtGui

class A(object):
    def __init__(self):
        # catch access a non existing attribute
        try:
            print self.a, type(self.a)
        except AttributeError:
            pass

a = A()

# derive from a sip wrapped class
class B(QtCore.QDate):
    def __init__(self):
        super(B, self).__init__()
        try:
            print self.b, type(self.b)
        except AttributeError:
            pass

b = B()

#app = QtGui.QApplication([])

# derive from a sip wrapped class
class C(QtCore.QObject):
    def __init__(self):
        super(C, self).__init__()
        # access a non existing attribute results in:
        # TypeError: 'sip.methoddescriptor' object is not callable
        try:
            print self.c, type(self.c)
        except AttributeError:
            pass

c = C()


results in

Traceback (most recent call last):
  File "sipinstance-v2.py", line 38, in <module>
    c = C()
  File "sipinstance-v2.py", line 34, in __init__
    print self.c, type(self.c)
TypeError: 'sip.methoddescriptor' object is not callable

Instancing QApplication or not doesn't seem to matter here, though.

Given, that at least another report for win32 exists, this issue is may 
be more involved, than it appears on the surface.

Pete