[Python-Dev] PEP 515: Underscores in Numeric Literals (revision 3)

Guido van Rossum guido at python.org
Sat Mar 19 14:52:45 EDT 2016

All that sounds fine!

On Sat, Mar 19, 2016 at 11:28 AM, Stefan Krah <stefan at bytereef.org> wrote:
> Guido van Rossum <guido <at> python.org> writes:
>> So should the preprocessing step just be s.replace('_', ''), or should
>> it reject underscores that don't follow the rules from the PEP
>> (perhaps augmented so they follow the spirit of the PEP and the letter
>> of the IBM spec)?
>> Honestly I think it's also fine if specifying this exactly is left out
>> of the PEP, and handled by whoever adds this to Decimal. Having a PEP
>> to work from for the language spec and core builtins (int(), float()
>> complex()) is more important.
> I'd keep it simple for Decimal: Remove left and right whitespace (we're
> already doing this), then remove underscores from the remaining string
> (which must not contain any further whitespace), then use the IBM grammar.
> We could add a clause to the PEP that only those strings that follow
> the spirit of the PEP are guaranteed to be accepted in the future.
> One reason for keeping it simple is that I would not like to slow down
> string conversion, but thinking about two grammars is also a problem --
> part of the string conversion in libmpdec is modeled in ACL2, which
> would be invalidated or at least complicated with two grammars.
> Stefan Krah
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--Guido van Rossum (python.org/~guido)

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