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

Fernando Perez fperez.net@gmail....
Fri Mar 13 02:23:57 CDT 2009


On Thu, Mar 12, 2009 at 11:34 PM, Robert Kern <robert.kern@gmail.com> wrote:

> One possibility (that may be opening a can of worms) is to have two
> sets of operators, one that does "native" semantics (C for cdef longs,
> Python for Python ints) and one that does Python semantics even on
> cdef longs. I leave it to you to decide which one gets blessed with
> "%" and which has to use the alternate ("~%"? there's a whole PEP
> sitting around which goes over various options).

Without going into the whole pep 225 discussion, would it make sense
for this particular case only, to consider instead a new %% operator?
It could be the partner to the (/,//) pair that provide Python/C
semantics for division, perhaps.  That way, we'd know that the
division-like operators come in 2 variants.  We already know that the
moment we do

cdef i

that thing will not behave like a python int (e.g., its overflow
behavior becomes constrained to what happens inside of a finite
bit-width, instead of having Python's auto-growth into arbitrary
length ints).  So it seems acceptable to me that once I cdef integer
variables, I'll need to keep the C/Python semantics in mind for / and
%, and having pairs (/,//), (%,%%) of operators to access each type of
behavior sounds reasonable to me.

Just a thought.

Cheers,

f


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