[Python-Dev] 2.1.1 maintenance branch

[Neil Schemenauer]

Guido van Rossum wrote:
> I'n curious about abstract_isinstance -- is that what you checked in
> last night?

Yes.

> I thought that was for 2.2 but I may have misunderstood
> the issue (I have to admit I have no idea what abstract_isinstance
> does any more :-( ).

No, abstract_isinstance has been broken for a long time, maybe forever.
It is supposed to work for class-like objects like ExtensionClass
instances as well as for standard classes and types.  One problem was
that if you gave it a normal instance as the first argument but an
ExtensionClass as the second argument it raised a type error.  It's
annoying to us at the MEMS Exchange because we use ExtensionClasses and
isinstance all the time (Greg likes type checking).  We ended up
rewriting isinstance() and issubclass() in Python.  The average Python
user doesn't care.

  Neil