Property setter and lambda question

Ian Kelly ian.g.kelly at
Mon Jul 11 13:41:41 EDT 2011

On Mon, Jul 11, 2011 at 11:21 AM, Anthony Kong
<anthony.hw.kong at> wrote:
> Awesome, Thomas. The trick only works if there is only one leading
> underscore in the method names.
> The following example works as I expected for the derived class B.
> class A(object):
>     def __init__(self):
>         self.__not_here = 1
>     def _get_not_here(self):
>         return self.__not_here
>     def _set_not_here(self, v):
>         print "I am called"
>         self.__not_here = v
>     not_here = property(lambda self: self._get_not_here(), lambda self, v:
> self._set_not_here(v))
> class B(A):
>     def _set_not_here(self, v):
>         print "version B"
>         self.__not_here = v

It shouldn't.  You've still got the name __not_here used in both A and
B, so that the B version is setting a different attribute than the A
version (_B__not_here vs. _A__not_here).

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