Dag Sverre Seljebotn wrote:
> Stefan Behnel wrote:
>> Dag Sverre Seljebotn wrote:
>>> I happen to routinely write (some complex integer expression)**2 in
>>> Python, and it is tedious to manually store the expression in a
>>> temporary
>>> etc. in Cython.
>
>> If you can come up with a sensible utility function that handles the
>> different C compile time and runtime overflow cases nicely, I'm all for
>> it.
>
> So you are "+1 if I include an overflow check"?
>
> I was just thinking of letting it silently overflow, the way addition
> and multiplication already silently overflows.
Hmm, yes, you are right. When a user writes
cdef int tinyint = 2**2000
it's not Cython's fault if it overflows.
So I guess I'm actually +1 for a fix that provides Python integer power
semantics modulo C overflows/wrap-arounds. I guess that would be the
semantics with the lowest probability of surprise.
Would you say that this makes sense as a utility function?
I mean, we could always write out the bit-shifting code for a constant
exponent...
http://c2.com/cgi/wiki?IntegerPowerAlgorithm
Stefan
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