[Python-Dev] PEP 515: Underscores in Numeric Literals (original) (raw)

Petr Viktorin encukou at gmail.com
Thu Feb 11 05:24:58 EST 2016

On 02/11/2016 11:07 AM, Nick Coghlan wrote:

On 11 February 2016 at 19:59, Victor Stinner <victor.stinner at gmail.com> wrote:

2016-02-11 9:11 GMT+01:00 Georg Brandl <g.brandl at gmx.net>:

On 02/11/2016 12:04 AM, Victor Stinner wrote:

It looks like the implementation https://bugs.python.org/issue26331 only changes the Python parser.

What about other functions converting strings to numbers at runtime like int(str) and float(str)? Paul also asked for Decimal(str). I added these as "Open Questions" to the PEP. Ok nice. Now another question :-) Would it be useful to add an option to repr(int) and repr(float), or a formatter to int.format() and float.float() to add an underscore for thousands. Given that str.format supports a thousands separator: "{:,d}".format(100000000) '100,000,000' it might be reasonable to permit "" in place of "," in the format specifier. However, I'm not sure when you'd use it aside from code generation, and you can already insert the thousands separator and then replace "," with "".

It would make "SI style" [0] numbers a little bit more straightforward to generate, since the order of operations wouldn't matter. Currently it's:

"{:,}".format(1234.5678).replace(',', ' ').replace('.', ',')

Also it would make numbers with decimal comma and dot as separator a bit easier to generate. Currently, that's (from PEP 378):

format(n, "6,f").replace(",", "X").replace(".", ",").replace("X", ".")

[0] https://en.wikipedia.org/wiki/Decimal_mark#Examples_of_use

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