[Python-Dev] PEP 515: Underscores in Numeric Literals
Terry Reedy
tjreedy at udel.edu
Thu Feb 11 12:39:07 EST 2016
On 2/11/2016 2:45 AM, Georg Brandl wrote:
Thanks for grabbing this issue and moving it forward. I will like being
about to write or read 200_000_000 and be sure I an right without
counting 0s.
> Based on the feedback so far, I have an easier rule in mind that I will base
> the next PEP revision on. It's basically
>
> "One ore more underscores allowed anywhere after a digit or a base specifier."
>
> This preserves my preferred non-restrictive cases (0b_1111_0000, 1.5_j) and
> disallows more controversial versions like "1.5e_+_2".
I like both choices above. I don't like trailing underscores for two
reasons.
1. The stated purpose of adding '_'s is to visually separate. Trailing
underscores do not do that. They serve no purpose.
2. Trailing _s are used to turn keywords (class) into identifiers
(class_). To me, 123_ mentally clashes with this usage.
If trailing _ is allowed, to simplify the implementation, I would like
PEP 8, while on the subject, to say something like "While trailing _s on
numbers are allowed, to simplify the implementation, they serve no
purpose and are strongly discouraged".
--
Terry Jan Reedy
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