Re: [boost] Boost.Parser questions

On Wed, Feb 28, 2024 at 3:26 PM Richard via Boost wrote:

In article you write:

...

I should have mentioned -- I recently removed the ascii::* parsers, which used is_*() from the C standard library. It included ascii::alnum. I removed them because those is_*() functions are considered just plain wrong by me and lots of other people from SG-16 (the committee's Unicode study group).

Is there a link to some discussion about why they are considered 'wrong'? Certainly they're correct for ASCII.

Yeah, but if you switch to using Unicode, you have some problems. https://daniel.haxx.se/blog/2018/01/30/isalnum-is-not-my-friend For the lazy: the values returned by these functions depends on the locale. The locale is global state that can be set by anyone, at any time, and is not concurrency-safe. You can set it, call isalnum(), and get a locale that is not the one you just set. They're a mess, as is absolutely everything that depends on locale. FWIW, there are even locales for EBCDIC that make even your ASCII-range values wrong. Zach