PySide Python3 Properties problem

danilo2

Hi! I'm new to Pyside and I was looking at the basic tutorials (http://qt-project.org/wiki/Using_Qt_Properties_in_PySide). I have found out, that the Properties does not work in Python3 as expected. Please take a look at:
@class MyObject(QObject):
def init(self,startval=42):
self.ppval = startval

def readPP(self):
    return self.ppval

def setPP(self,val):
    self.ppval = val

pp = Property(int, readPP, setPP)

obj = MyObject()
obj.pp = 47
print (obj.pp)@

In Python3 you get:
@<Property object at 0x2f39948>@
as a result, and it should return 47.

bootchk

I don't have the answer, but found the question interesting.

Your example should be more complete. I found that Property is defined by PySide. So you should add to your example:

@from PySide.QtCore import QObject, Property@

But calling the standard Python property works:

@pp = property(readPP, setPP) @

I am left wondering what the documentation means "simultaneously behave both as Qt and Python properties"? What does "Qt property" give you?

Could it have something to do with not embedding in a larger Qt application where signals are initialized?

lndn

This is what works for me:

@
from PySide.QtCore import QObject, Property

class MyObject(QObject):
def init(self,startval=42):
self.ppval = startval

def readPP(self):
    return self.ppval

def setPP(self,val):
    self.ppval = val

pp = Property(int, readPP, setPP)

obj = MyObject()
print(obj.readPP()) # Should print 42
obj.setPP(47)
print(obj.readPP()) # Should print 47

@

bootchk

Indn: aren't you missing the point: you should be able to access the value of a property by simply referring to the attribute 'obj.pp', without needing to call the getter method 'obj.readPP().' Its related to "Command Query Separation Principle": a query should not need call syntax (with '()') even if some computation (getter method) is involved.

lndn

This works. The parent QObject needs to be initialized (see 5th line).

@
from PySide.QtCore import QObject, Property

class MyObject(QObject):
def init(self,startval=42):
QObject.init(self)
self.ppval = startval

def readPP(self):
    return self.ppval

def setPP(self,val):
    self.ppval = val

pp = Property(int, readPP, setPP)

obj = MyObject()
obj.pp = 47
print (obj.pp)
@

lndn

You can also call the parent QObject with the super() method.

@
from PySide.QtCore import QObject, Property

class MyObject(QObject):
def init(self,startval=42):
super().init()
self.ppval = startval

def readPP(self):
    return self.ppval

def setPP(self,val):
    self.ppval = val

pp = Property(int, readPP, setPP)

obj = MyObject()
obj.pp = 47
print (obj.pp)
@