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understanding 'property' / making value read-only
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Achim Domma
Dec 29, 2002, 7:30:42 AM12/29/02
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Hi,
I wrote the following example:
class Demo:
def __init__(self,value):
self._value = value
def _getValue(self):
print "_getValue"
return self._value
value = property(_getValue,None,None,"DocString")
a = Demo(10)
print a.value
a.value = 15
print a.value
and the output is:
_getValue
10
15
Why can I still set 'value'? Is it possible at all to make it read-only or
do I have to write a funktion _setValue(self,value) which raises an
exception?
regards,
Achim
Gonçalo Rodrigues
Dec 29, 2002, 7:59:19 AM12/29/02
to
On Sun, 29 Dec 2002 13:30:42 +0100, "Achim Domma" <achim...@syynx.de>
wrote:
wrote:
You have to make Demo a subclass of some new-style class for properties
to work right. Old-style classes do not go well with properties, e.g.
something like
class Demos(object):
<whatever>
is enough.
>
>regards,
>Achim
>
With my best regards,
G. Rodrigues
Achim Domma
Dec 29, 2002, 7:48:15 AM12/29/02
to
I just found it out myself: I have to use new-style classes, so deriving
Demo from object makes it work!
Demo from object makes it work!
Laura Creighton
Dec 29, 2002, 7:06:04 PM12/29/02
to
Perhaps http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/59878
already does what you want.
already does what you want.
Laura Creighton
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