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Subject: Re: LWG3576 - Clarifying fill character in std::format
From: Victor Zverovich (victor.zverovich_at_[hidden])
Date: 2021-08-09 10:35:36

As an additional data point: the {fmt} library and Python's str.format use
code points.

- Victor

On Mon, Aug 9, 2021 at 8:34 AM Victor Zverovich <victor.zverovich_at_[hidden]>

> Thanks Corentin for bringing this up. I think this should be at least a
> code point (that was the original intent which was lost to wording
> ambiguity), otherwise fill is pretty much useless. Grapheme cluster is an
> option but might be an overkill.
> Cheers,
> Victor
> On Mon, Aug 9, 2021 at 8:30 AM Corentin <corentin.jabot_at_[hidden]> wrote:
>> Hello,
>> I wanted to bring this new LWG issue to your attention.
>> https://cplusplus.github.io/LWG/issue3576
>> The author asks whether the fill character of std::format is
>> - a code unit
>> - a code point
>> - a grapheme cluster
>> This might be an abi breaking thing, and implementation disagrees already
>> apparently.
>> My gut feeling is that it needs to at least be a codepoint.
>> I do not know if there are any concerns with allowing a grapheme in terms
>> of implementation or performance. There is definitively some motivation,
>> especially for non-nfc format strings.
>> This sort of issue illustrates my point that using the term character in
>> the standard can be problematic!
>> Thanks,
>> Have a great week,
>> Corentin

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