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[Python-Dev] PEP 572: Assignment Expressions

Steve Holden steve at holdenweb.com
Tue Apr 24 07:37:06 EDT 2018 
What facilities does the interpreter currently have for extracting common
subexpressions, and how would it verify in such a dynamic environment that
such extractions wouldn't alter the semantics of the program? Explicit
(assignment using :=) is better than implicit (by optimizations hidden to
the programmer).

regards
 Steve

Steve Holden

On Mon, Apr 23, 2018 at 6:13 PM, Sven R. Kunze <srkunze at mail.de> wrote:

> On 23.04.2018 17:59, Steve Holden wrote:
>
>
> While Tim's expression might look (superficially) like C, the five-line
> alternative isn't exactly an inspiring example of Pythonicity, is it?
>
>
> What about
>
> diff = x - x_base
> if diff and gcd(diff, n) > 1:
>     return gcd(diff, n)
>
> # or
>
> if (x - x_base) and gcd(x - x_base, n) > 1:
>     return gcd(x - x_base, n)
>
>
>
> and have the interpreter handle the optimization, or apply an lru_cache?
> ;-)
>
> Cheers,
> Sven
>
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