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[Python-Dev] Re: the "3*x works w/o __rmul__" bug

Guido van Rossum guido at python.org
Tue Oct 28 13:37:56 EST 2003 
> You're making a mountain of a molehill here, Alex.  I know that in
> group theory there are non-Abelian groups (for which AB != BA), but
> I've never encountered one myself in programming; more typical such
> non-commutative operations are modeled as __add__ rather than as
> __mul__.

I need to give myself a small slap on the forehead head, because of
course non-square matrix multiplication is an excellent example where
AB != BA.  However even there, Ax == xA when x is a singleton, and the
issue only arises for integers, so I still don't think there are use
cases.

--Guido van Rossum (home page: http://www.python.org/~guido/)
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