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[Python-Dev] Examples for PEP 572

Yury Selivanov yselivanov.ml at gmail.com
Wed Jul 4 13:50:48 EDT 2018 
On Wed, Jul 4, 2018 at 1:35 PM Ivan Pozdeev via Python-Dev
<python-dev at python.org> wrote:
>
> On 04.07.2018 11:54, Serhiy Storchaka wrote:

> >> while total != (total := total + term):
> >>     term *= mx2 / (i*(i+1))
> >>     i += 2
> >> return total
> >
> > This code looks clever that the original while loop with a break in a
> > middle. I like clever code. But it needs more mental efforts for
> > understanding it.
> >
> > I admit that this is a good example.
> >
> > There is a tiny problem with it (and with rewriting a while loop as a
> > for loop, as I like). Often the body contains not a single break. In
> > this case the large part of cleverness is disappeared. :-(
>
> It took me a few minutes to figure out that this construct actually
> checks term == 0.

Wow, I gave up on this example before figuring this out (and I also
stared at it for a good couple of minutes).  Now it makes sense.  It's
funny that this super convoluted snippet is shown as a good example
for PEP 572.  Although almost all PEP 572 examples are questionable.

Yury
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