[Python-Dev] PEP 515: Underscores in Numeric Literals

[Brett Cannon]

On Thu, 11 Feb 2016 at 00:23 Georg Brandl <g.brandl at gmx.net> wrote:

> Hey all,
>
> based on the feedback so far, I revised the PEP.  There is now
> a much simpler rule for allowed underscores, with no exceptions.
> This made the grammar simpler as well.
>
> ---------------------------------------------------------------------------
>
> PEP: 515
> Title: Underscores in Numeric Literals
> Version: $Revision$
> Last-Modified: $Date$
> Author: Georg Brandl
> Status: Draft
> Type: Standards Track
> Content-Type: text/x-rst
> Created: 10-Feb-2016
> Python-Version: 3.6
>
> Abstract and Rationale
> ======================
>
> This PEP proposes to extend Python's syntax so that underscores can be
> used in
> integral, floating-point and complex number literals.
>
> This is a common feature of other modern languages, and can aid
> readability of
> long literals, or literals whose value should clearly separate into parts,
> such
> as bytes or words in hexadecimal notation.
>
> Examples::
>
>     # grouping decimal numbers by thousands
>     amount = 10_000_000.0
>
>     # grouping hexadecimal addresses by words
>     addr = 0xDEAD_BEEF
>
>     # grouping bits into bytes in a binary literal
>     flags = 0b_0011_1111_0100_1110
>
>     # making the literal suffix stand out more
>     imag = 1.247812376e-15_j
>
>
> Specification
> =============
>
> The current proposal is to allow one or more consecutive underscores
> following
> digits and base specifiers in numeric literals.
>

+1 from me. Nice and simple! And we can always update PEP 8 do disallow any
usage that we deem ugly.
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