Re: Character folding in the pretest

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 5 Feb 2016 14:36:13 +0800
> From: Elias Mårtenson <lokedhs@gmail.com>
> Cc: Óscar Fuentes <ofv@wanadoo.es>,
> 	emacs-devel <emacs-devel@gnu.org>
> 
> What I did want to do was try try to explain that even though there is a visual similarity between A, Ä and Å, to
> a Swedish speaker those similarities are no greater than those of q and k. And definitely much more different
> than W and V (which were, up until recently sorted under V in dictionaries and seen as simply a visual
> variation).
> 
> 
>  What you describe naturally leads to another user option: Don't handle
>  characters as `equal' (with a proper definition of `equal') that
>  aren't `equal' in the user's locale.
> 
> This is exactly my point. And you have managed to compress hundreds of my words into a single, district
> sentence. Thank you. 

We are not going by visual similarity, or any other arbitrary
criteria.  We are using established rules specified by the UCD, the
Unicode Character Database, and the explanations that accompany it in
the standard itself.  The main rule is equivalent character strings
should match (when character folding is enabled).

That character equivalence is language-dependent is a truism that
doesn't need to be argued.  The plan is to have language-dependent
variations as soon as Emacs acquires good infrastructure for doing
that in a useful manner.  The idea behind the current implementation
was that this feature will be useful even when it is
language-agnostic, which is the lowest level of compatibility cited in
the Unicode Standard (so the Unicode Consortium guys didn't think it
to be a stupid idea).