[Python-ideas] Adding str.isascii() ?

Guido van Rossum guido at python.org
Wed Jan 31 11:28:12 EST 2018

For the record, I encouraged this. I see no reason to amend my decision.
Only .isascii(), for str, bytes, bytearray. No ascii=<bool> flags to other

On Wed, Jan 31, 2018 at 4:17 AM, Serhiy Storchaka <storchaka at gmail.com>

> 31.01.18 13:18, INADA Naoki пише:
>> Yes.  But .isascii() will be match faster than try ...
>> .encode('ascii') ... except UnicodeEncodeError
>> on most Python implementations.
> In this case this doesn't matter since this is an exceptional case, and in
> any case an exception is raised for non-ascii string.
> But you are true that str.isascii() can be faster than str.encode(), and
> encoding is not required for converting to int.
> Other possibility -- adding support of the boolean argument in
>>> str.isdigit()
>>> and similar predicates that switch them to the ASCII-only mode. Such
>>> option
>>> will be very useful for the str.strip(), str.split() and str.splilines()
>>> methods. Currently they split using all Unicode whitespaces and line
>>> separators, but there is a need to split only on ASCII whitespaces and
>>> line
>>> separators CR, LF and CRLF. In case of str.strip() and str.split() you
>>> can
>>> just pass the string of whitespace characters, but there is no such
>>> option
>>> for str.splilines().
>> It sounds good idea.  Maybe, keyword only argument `ascii=False`?
> There is an issue for str.splilines() (don't remember the number). The
> main problem was that I was not sure about an obvious argument name.
> But if revert adding str.isascii() from Python 3.7, same keyword-only
>> argument should be
>> added to int(), float(), decimal.Decimal(), fractions.Fraction(),
>> etc...  It's bit hard.
> Ah, it is already committed. Then I think it is too later to revert this.
> I had doubts about this feature and were -0 for adding it (until we discuss
> it more), but since it is added I don't see much benefit from removing it.
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--Guido van Rossum (python.org/~guido)
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