[Python-Dev] NotImplemented reaching top-level

[Armin Rigo]

Hi Reinhold,

On Sun, Dec 25, 2005 at 12:37:53PM +0100, Reinhold Birkenfeld wrote:
> > that nobody fully understands the convoluted code paths of abstract.c
> > any more :-(
> 
> Time for a rewrite?

Of course, speaking of a rewrite, PyPy does the "right thing" in these
two areas.  Won't happen to CPython, though.  There are too much
backward-compatibility issues with the PyTypeObject structure; I think
we're doomed with patching the bugs as they show up.

Looking up in the language reference, I see no mention of NotImplemented
in the page about __add__, __radd__, etc.  I guess it's a documentation
bug as well, isn't it?  The current code base tries to implement the
following behavior: Returning NotImplemented from any of the binary
special methods (__xxx__, __rxxx__, __ixxx__) makes Python proceed as if
the method was not defined in the first place.

If we agree on this, I could propose a doc fix, a test, and appropriate
bug fixes.


A bientot,

Armin