[Python-Dev] pyc files, constant folding and borderline portability issues (original) (raw)
Fredrik Johansson fredrik.johansson at gmail.com
Tue Apr 7 21:09:26 CEST 2009
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On Tue, Apr 7, 2009 at 8:59 PM, Alexandru Moșoi <brtzsnr at gmail.com> wrote:
Not necessarily. For example C/C++ doesn't define the order of the operations inside an expression (and AFAIK neither Python) and therefore folding 2 * 3 is OK whether b is an integer or an arbitrary object with mul operator overloaded. Moreover one would expect * to be associative and commutative (take a look at Python strings); if a * 2 * 3 returns a different result from a * 6 I will find it very surprising and probably reject such code.
Multiplication is not associative for floats:
a = 0.1 a35 1.5000000000000002 a*(3*5) 1.5
Fredrik
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