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On 2/10/2016 2:20 PM, Georg Brandl wrote:
This came up in python-ideas, and has met mostly positive comments,  
although the exact syntax rules are up for discussion.


cheers,
Georg


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PEP: 515
Title: Underscores in Numeric Literals
Version: RevisionRevisionRevision
Last-Modified: DateDateDate
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 and floating-point 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




+1



You don't mention potential restrictions that decimal numbers should
permit them only every three places, or hex ones only every 2 or 4,
and your binary example mentions grouping into bytes, but actually
groups into nybbles.



But such restrictions would be annoying: if it is useful to the
coder to use them, that is fine. But different situation may find
other placements more useful... particularly in binary, as it might
want to match widths of various bitfields.



Adding that as a rejected consideration, with justifications, would
be helpful.