[PyKDE] pyqt and new-style classes

[Ulrich Berning]

Phil Thompson schrieb:

>On Wednesday 18 February 2004 19:04, Eron Lloyd wrote:
>  
>
>>Would there be any benefit in doing this? From the way I understand it, all
>>Qt objects already expose their get/set methods, while any objects you
>>create through subclassing can simply use Python's native properties
>>support. For the most part, properties have their biggest value in use with
>>Designer.
>>
>>Eron
>>    
>>
>
>I agree, it just duplicates existing functionality at the cost of code bloat.
>
>  
>
Not only code bloat, also a performance penalty.

Look at the following test class and the two methods to get and set an 
attribute:

--------------------------------------------------
class PropertyTest(object):
    def getValue(self):
        return self._value
    def setValue(self, value):
        self._value = value
    value = property(getValue, setValue, None)
--------------------------------------------------
x = PropertyTest()
for i in xrange(100000):
    x.setValue("TEST")
    a = x.getValue()
    x.setValue(a.swapcase())
--------------------------------------------------
x = PropertyTest()
for i in xrange(100000):
    x.value = "TEST"
    a = x.value
    x.value = a.swapcase()
--------------------------------------------------

On my Linux box with Python-2.3.3, the second method has only *~75%* of 
the performance of the first method.

Nevertheless it makes sense to implement QMetaObject and QMetaProperty, 
just in case someone plans to build a kind of dialog editor with PyQt 
(in the future, we want to give our customers the facility to create or 
modify dialogs or dialog components inside the application).

Ulli

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