data attributes override method attributes?

[Prasad, Ramit]

Terry Reedy wrote:
> On 9/25/2012 4:07 PM, Ian Kelly wrote:
> > On Tue, Sep 25, 2012 at 1:58 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> >> On 9/25/2012 11:03 AM, Chris Angelico wrote:
> >>> Instance attributes override (shadow) class attributes.
> >>
> >>
> >> except for (some? all?) special methods
> >
> > Those names are shadowed too.  If you call foo.__len__() and the name
> > is bound on the instance, it will call that function preferentially.
> > It's just that when the special Python machinery calls the method, it
> > skips the instance and goes straight to the class.
> 
> I added "Ian Kelly reminds me that instance.__xxx__ is only skipped by
> the internal machinery and not by direct accesses in user code. In the
> other hand, docs, official or otherwise, are filled with things like
> 'len(a) calls a.__len__', so I think something should be said that
> giving instances special method attributes does not have the effect one
> might expect."
> 
> to the issue.
> 


Just to make sure I am following, if you call
foo.__len__() it goes to the instance code while
if you do len(foo) it will go to class.__len__()?

If so, why? 

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