[Numpy-discussion] Poll: Semantics for % in Cython

[Chris Colbert]

On Tue, May 4, 2010 at 12:20 PM, S. Chris Colbert <sccolbert at gmail.com>wrote:

> On Thu, 2009-03-12 at 19:59 +0100, Dag Sverre Seljebotn wrote:
> > (First off, is it OK to continue polling the NumPy list now and then on
> > Cython language decisions? Or should I expect that any interested Cython
> > users follow the Cython list?)
> >
> > In Python, if I write "-1 % 5", I get 4. However, in C if I write "-1 %
> > 5" I get -1. The question is, what should I get in Cython if I write (a
> > % b) where a and b are cdef ints? Should I
> >
> > [ ] Get 4, because it should behave just like in Python, avoiding
> > surprises when adding types to existing algorithms (this will require
> > extra logic and be a bit slower)
> >
> > [ ] Get -1, because they're C ints, and besides one isn't using
> > Cython if one doesn't care about performance
> >
> > Whatever we do, this also affects the division operator, so that one in
> > any case will have a==(a//b)*b+a%b.
> >
> > (Orthogonal to this, we can introduce compiler directives to change the
> > meaning of the operator from the default in a code blocks, and/or make
> > special functions for the semantics that are not chosen as default.)
> >
>
> I definitely fall into the "I prefer C semantics" crowd. Because my
> brain is in "C" mode whenever I write Cython. However, I totally
> understand the arguments from the other side, and I would not be upset
> if Cython went in that direction.
>
> You could say that I have my preference, but I can't make a strong
> argument for it.
>
> Chris
>
>
It seems I was a little late to the party. The mail client's sort-by-date
was reversed. My apologies.
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