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

[S. Chris Colbert]

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