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

[Paul Moore]

On 12 February 2016 at 00:16, Steven D'Aprano <steve at pearwood.info> wrote:
> I think that there is broad agreement that:
>
> - the basic idea is sound
> - leading underscores followed by digits are currently legal
>   identifiers and this will not change
> - underscores should not follow the sign - +
> - underscores should not follow the decimal point .
> - underscores should not follow the exponent e|E
> - underscores will not be permitted inside the exponent (even if
>   it is harmless, it's silly to write 1.2e9_9)
> - underscores should not follow the complex suffix j
>
> and only minor disagreement about:
>
> - whether or not underscores will be allowed after the base
>   specifier 0x 0o 0b
> - whether or not underscores will be allowed before the decimal
>   point, exponent and complex suffix.
>
> Can we have a show of hands, in favour or against the above two? And
> then perhaps Guido can rule on this one way or the other and we can get
> back to arguing about more important matters? :-)
>
> In case it isn't obvious, I prefer to say No to allowing underscores
> after the base specifier, or before the decimal point, exponent and
> complex suffix.

I have no opinion on anything other than that whatever syntax is
implemented as long as it allows single underscores between digits,
such as

1_000_000

Everything else is irrelevant to me, and if I read code that uses
anything else, I'd judge it based on readability and style, and
wouldn't care about arguments that "it's allowed by the grammar".

Paul