[Tutor] if n == 0 vs if not n

Andre Engels andreengels at gmail.com
Tue Oct 6 17:40:06 CEST 2009

On Tue, Oct 6, 2009 at 5:08 PM, Wayne <srilyk at gmail.com> wrote:
> On Tue, Oct 6, 2009 at 9:58 AM, Dave Angel <davea at ieee.org> wrote:
>> <snip>
>> No, because you're not assured that all integers that are equal are the
>> same object.  Python optimizes that for small integers, but there's no
>> documented range that you can count on it.
> But for this specific case - checking a return code against zero, should it
> still be considered unreliable? The only case that you are looking for
> correctness is 0 == 0, any other case should evaluate as false, so I guess
> the question is does python always optimize for zero? Any other optimization
> is irrelevant, AFAIK.

Never rely on optimizations like this being done, or on them not being
done. The only save way to code is having your code work in both

André Engels, andreengels at gmail.com

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