__delitem__ "feature"

[Christian Heimes]

Am 26.12.2010 18:53, schrieb kj:
> It means that, for both subclasses, del fails to trigger the
> dynamically installed instance method __delitem__.

Magic methods like __delitem__ are looked up on the type, not on the
instance. You can't change the behaviour on instances.

> If I replace dict with UserDict, *both* deletion attempts lead to
> a call to the dynamic __delitem__ method, and are thus blocked.
> This is the behavior I expected of dict (and will help me hold on
> to my belief that I'm not going insane when inevitably I'm told
> that there's no bug in dict or list).

UserDict is an old style class (not a subclass of object). Old style
classes behave differently.

Christian