super problem

[Uwe Mayer]

Hi,

I have a diamond-shaped multiple inheritanc chain with new style classes,
but super() does not call the parent class correctly:

-- snip --
from qtcanvas import *

class B2(QCanvasItem):
def move(self, x,y):
super(B2, self).move(0,0)
print "B2"

class C2(QCanvasItem):
def move(self, x,y):
super(C2, self).move(0,0)
print "C2"

class D2(QCanvasPolygonalItem, B2, C2):
def move(self, x,y):
super(D2, self).move(0,0)
print "D2"

d2 = D2(None)
d2.move(0,0)
-- snip --
returns:

Traceback (most recent call last):
File "tmp.py", line 46, in ?
d2.move(0,0)
File "tmp.py", line 42, in move
super(D2, self).move(0,0)
File "tmp.py", line 32, in move
super(B2, self).move(0,0)
File "tmp.py", line 37, in move
super(C2, self).move(0,0)
AttributeError: 'super' object has no attribute 'move'

super(C2, self).move(0,0) should resolve to QCanvasItem.move
AFAIK super only works with new-style classes, so I checked:
True


A way to fix this is to introduce a dummy

class A2(QCanvasItem):
def move(self,x,y): QCanvasItem.move(self,x,y)

This is stupid, as it only delays execution by one intermediary call.


Is this a bug?

Thanks,
Ciao
Uwe

 

[Michael Hoffman]

I have a diamond-shaped multiple inheritanc chain with new style classes,
but super() does not call the parent class correctly:

-- snip --
from qtcanvas import *

I don't have qtcanvas installed, and I couldn't reproduce the
undesirable behavior using a dummy class. If you try to create a
self-contained testcase, you will have an easier time figuring where the
problem is.

 

[Konstantin Veretennicov]

AFAIK super only works with new-style classes, so I checked:

True

AFAIK, this is not the right way to check for new-styledness:
True

But this is:
False

- kv