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Re: [SG16] Agenda for the 2021-03-24 SG16 telecon

From: Corentin Jabot <corentinjabot_at_[hidden]>
Date: Wed, 17 Mar 2021 21:18:11 +0100
On Wed, Mar 17, 2021, 21:09 Tom Honermann via SG16 <sg16_at_[hidden]>

> On 3/17/21 10:45 AM, Steve Downey via SG16 wrote:
> On Wed, Mar 17, 2021 at 9:22 AM Tom Honermann via SG16 <
> sg16_at_[hidden]> wrote:
>> On 3/17/21 5:23 AM, Corentin Jabot wrote:
>> On Tue, Mar 16, 2021 at 3:59 PM Tom Honermann via SG16 <
>> sg16_at_[hidden]> wrote:
>>> - P1628 <https://wg21.link/p1628>: Unicode character properties
>>> As the author I do not expect to do further work on this in the 23 cycle
>> That matches my expectations, thanks for confirming.
> Not that we have a paper, or that I'm asking for anyone to do work, but
> without access to the UCD, all the other algorithms are off the table. In
> theory it's an implementation detail, in practice it would be an ABI break
> to change the APIs for property lookup, and having two or more mechanisms
> in a std library implementation seems like a bad idea.
> Expectation setting is important. It's not clear to everyone how the
> Unicode layers work, even if the explanations are straight-forward.
> We don't have proposals for any algorithms yet. I would feel some concern
> about trying to standardize access to the UCD without algorithms to go with
> it; at least reference implementations showing what is possible.
> Perhaps something that might be helpful is an audit of the algorithms and
> which UCD properties they each depend on. That might help to prioritize
> which UCD properties to expose first, which ones we can guarantee stability
> for, etc...

Properties and algorithms are related in that some algorithms depend on
some properties, but that doesn't inform the design of the properties paper.
At all.

For example, the XID_ properties are useful to write a compiler
independently of Unicode algorithms.
Ignoring diatrics from search is something browsers and other applications
implement by looking at properties without it being a Unicode defined
I can definitely offer more use cases in the paper.

Some algorithms (notably regexes) may need the data presented in slightly
different form.

We should have Unicode properties if we believe Unicode algorithms do not
cover the set of use cases for Unicode, not because we want to implement
Unicode algorithms

> Tom.
> --
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> SG16_at_[hidden]
> https://lists.isocpp.org/mailman/listinfo.cgi/sg16

Received on 2021-03-17 15:18:27