Question

I have a class like this, in which I have declared a property x, and overridden __delattr__:

class B(object):
    def __init__(self, x):
        self._x = x
    def _get_x(self):
        return self._x
    def _set_x(self, x):
        self._x = x
    def _del_x(self):
        print '_del_x'

    x = property(_get_x, _set_x, _del_x)

    def __delattr__(self, name):
        print '__del_attr__'

Now when I run

   b = B(1)
   del b.x

Only __del_attr__ get invoked, anybody knows why and how to solve this problem?

Answer 1

You have to call the __delattr__ of your ancestor to achieve this correctly.

class B(object): 
    .....

    def __delattr__(self, name):
        print '__del_attr__'
        super(B, self).__delattr__(name)     # explicit call to ancestor (not automatic in python)

And then running :

b = B(1)
del b.x

Will output:

__del_attr__
_del_x