Easy function, please help.

Jason Swails jason.swails at gmail.com
Thu Feb 10 21:40:33 CET 2011

On Thu, Feb 10, 2011 at 12:01 PM, Terry Reedy <tjreedy at udel.edu> wrote:

> On 2/10/2011 11:52 AM, Ethan Furman wrote:
>  Jason Swails wrote:
>  How is "while n != 0:" any worse?
> 1. It is redundant, just like 'if bool_value is not False:'.
> Python programmers should understand the null value idiom.
> 2. It does 2 comparisons, 1 unneeded, instead of 1. For CPython,
> it adds 2 unnecessary bytecode instructions and takes longer.

I see what you mean, and I think we're coming from different perspectives.
First I must say that the calculations I implement/use are VERY
computationally demanding and code optimization is of utmost importance, so
this point does not fall on deaf ears.  I agree that code optimization can
be very important.  However, the only things worth *optimizing*, really, is
the RDS.  Optimizing parts of the program that consume ~5% of the total
operation time to run ~20% faster is only ~ 0.1% increase in total
performance -- a sacrifice I'm more than willing to make for code
readability (as a general philosophy).

These programs are also very large, collaborative efforts that necessarily
have many people working on it, modifying it, etc.  It's this reason why I
say that sometimes code readability trumps performance.

>  It has exactly the same effect without adding any code
> Untrue, see above.

What I meant was that the function result is unchanged without adding more
LOC; not that it was the same on the instruction level.

I think this is just a difference of perspective: mine is almost strictly
utilitarian, in that I just use languages/code/computers to solve my

All the best,

> --
> Terry Jan Reedy
> --
> http://mail.python.org/mailman/listinfo/python-list

Jason M. Swails
Quantum Theory Project,
University of Florida
Ph.D. Graduate Student
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