[Tutor] Class Construction question [C++ and Python class introduction]

[Magnus Lycka]

At 14:38 2002-11-13 +0100, Yigal Duppen wrote:
>Even better, (something I realised only recently), as of Python2.2 you can
>also change a normal attribute to a property! No more fidgeting with the
>(quite dangerous IMHO) __getattr__ and __setattr__.

Right, I forgot about new style classes.

>class C(object):
>
>         def __init__(self):
>                 self.a = 10
>
>         def setA(self, a):
>                 self._a = a
>
>         def getA(self):
>                 return self._a
>
>         a = property(getA, setA, None, "a is now a property!!")

This is obviously much cleaner if you have several attribute
that you want to wrap up, since you don't have to mix all get
methods in the class in one __getattr__ and all set methods in
one __setattr__.

This is something to use if you don't need to support python
versions older than 2.2 and don't run into special problems.
For instance I realized I couldn't inherit from both new style
classes and ZODB's Persistent base class. I decided to leave
new style classes alone until 2.3, hoping that some issues will
be solved by then.


-- 
Magnus Lycka, Thinkware AB
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