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

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 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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