[PySide] Questions about QProperties

[Christian Gagneraud]

Hi list,

[I'm using PySide-1.1.0 and Qt-4.7.4 on an OpenSuse-12.1]

I don't if it's me doing something wrong, but I'm having trouble getting 
basic things working with QProperties and inheritance.

First I tried to define properties using the decorator syntax like this:

@QtCore.Property(float)
def toto(self)
   return self._toto

@toto.setter(self, value)
   self._toto = value

And it simply doesn't work, the setter is never called.

Then i decided to go with:
toto = QtCore.Property(float, get_toto, set_toto)

And it worked as expected, until I start using class derivation. Here is 
a basic use case:

from PySide import QtCore

class Obj1(QtCore.QObject):

     def __init__(self):
         super(Obj1, self).__init__()
         self._toto = 0.0

     def get_toto(self):
         print "get toto"
         return self._toto

     def set_toto(self, value):
         print "set toto"
         self._toto = value

     toto = QtCore.Property(float, get_toto, set_toto)

class Obj2(QtCore.QObject):

     def __init__(self):
         super(Obj2, self).__init__()

o1 = Obj1()
print o1.property("toto")
o1.setProperty("toto", 1.23)
print o1.property("toto")
print ""
o2 = Obj2()
print o2.property("toto")
o2.setProperty("toto", 1.23)
print o2.property("toto")

And here is the output:
get toto
0.0
set toto
get toto
1.23

None
1.23

So what happens here is obj1.toto works as expected, but obj2.toto 
doesn't, a new property "toto" is being created on obj2 and 
Obj1::get_toto is never called.
I would expect to be able to set an Obj1 property on an Obj2 instance 
when I call obj2.setProperty(...)
At least, this work in C++, but it doesn't work in my case.

This sounds so basic, that I couldn't believe it! So either i'm doing 
something wrong, or the python behaviour of a QObject is different from 
the C++ version, which sounds really odd to me....

Chris



-- 
Christian Gagneraud,
Embedded systems engineer.
Techworks Marine
1 Harbour road
Dun Laoghaire
Co. Dublin
Ireland
Tel: + 353 (0) 1 236 5990
Web: http://www.techworks.ie/