On Thu, Mar 12, 2009 at 17:45, Sturla Molden firstname.lastname@example.org wrote:
2009/3/13 Charles R Harris email@example.com:
That said, I think it best to leave '%' with its C default and add a special modulus function for the python version. Changing its meaning in C-like code is going to confuse things.
This is Cython code, so I think there is an argument to be made that it is Python-like!
I'll just repeat what I've already said on the Cython mailing list:
I think C types should behave like C types and Python objects like Python objects. If a C long suddenly starts to return double when divided by another C long, then that will be a major source of confusion on my part. If I want the behaviour of Python integers, Cython lets me use Python objects. I don't declare a variable cdef long if I want it to behave like a Python int.
That may be part of the confusion. The expression "-1%5" has no variables. Perhaps Dag can clarify what he is asking about:
# Constants? (No one uses just constants in expressions, # really, but consistency with the other choices will # affect this.) -1 % 5
# Explicitly declared C types? cdef long i, j, k i = -1 j = 5 k = i % j
# Python types? i = -1 j = 5 k = i % j
# A mixture? cdef long i i = -1 j = 5 k = i % j
When I do (2147483647 + 2147483647) in current Cython, to choose another operation, does it use C types, or does it construct PyInts? I.e., do I get C wraparound arithmetic, or do I get a PyLong?
I recommend making % behave consistently with the other operators; i.e. if <x>+<y> uses C semantics, <x>%<y> should, too.