Tricky Areas in Python

Fredrik Lundh fredrik at pythonware.com
Tue Oct 25 10:44:07 CEST 2005


Alex Martelli wrote:

>> my hard-won ignorance, and admit that I don't see the
>> problem with the property examples:
>>
>> >     class Sic:
>> >         def getFoo(self): ...
>> >         def setFoo(self): ...
>> >         foo = property(getFoo, setFoo)
>
> Sorry for skipping the 2nd argument to setFoo, that was accidental in my
> post.  The problem here is: class Sic is "classic" ("legacy",
> "old-style") so property won't really work for it (the setter will NOT
> trigger when you assign to s.foo and s is an instance of Sic).

what's slightly confusing is that the getter works, at least until you attempt
to use the setter:

>>> class Sic:
...     def getFoo(self):
...         print "GET"
...         return "FOO"
...     def setFoo(self, value):
...         print "SET", value
...     foo = property(getFoo, setFoo)
...
>>> sic = Sic()
>>> print sic.foo
GET
FOO
>>> sic.foo = 10
>>> print sic.foo
10

(a "setter isn't part of an new-style object hierarchy" exception would have
been nice, I think...)

</F> 






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