[Python-3000] __special__ attrs looked up on the type, not instance

[Neal Norwitz]

---------- Forwarded message from python-3000-checkins ----------

Neal Norwitz schrieb:
> I assume this is not the desired behaviour?
>
>>>> class F:
> ...   def __dir__(self):
> ...     return [5]
> ...
>>>> dir(F())
> [5]
>>>> f = F()
>>>> dir(f)
> [5]
>>>> def __dir__(): return [10]
> ...
>>>> f.__dir__ = __dir__
>>>> dir(f)
> [5]
>
> I think the problem is in _dir_object()
>
> +       PyObject * dirfunc = PyObject_GetAttrString((PyObject*)obj->ob_type,
> +                                                   "__dir__");
>
> Shouldn't the first arg just be obj, not obj->ob_type?

[Georg]
This is modeled after the principle that for new-style objects, __special__
methods are looked up on the type, not the instance.

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1) I didn't remember this, do we have it documented somewhere?
2) Assuming #1 is correct, is this rule consistently applied?
3) How does (should) this affect 2.6 and migration to 3.0, if at all?

n