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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Elaboration order handling (Was: Bug in 'gnatmake')
Date: Thu, 20 Jun 2013 16:36:13 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2013-06-20T16:36:13-05:00
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"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message 
news:wcc38sd7hch.fsf@shell01.TheWorld.com...
> "Randy Brukardt" <randy@rrsoftware.com> writes:
...
>> A direct conversion to some specific case doesn't work portably in 
>> Unicode
>> (because it depends on what version Unicode you are using, while the
>> case-insensitive compare is guarenteed to work the same in all versions 
>> of
>> Unicode).
>
> Wait, are you saying that it's impossible to implement a
> case-insensitive sort in unicode?  Such a sort is all that's needed
> here.

Of course not. You could do case-folding on each item, and do an ordered 
compare on that. It's well defined, but the ordering might be nonsense for 
some particular (natural) language. (Case-folding is designed for 
case-insensitive equality compares, the ordering is whatever it is.)

> Anyway, there's some "perfect/enemy/good-enough" thing going on here.
> Even solving the problem for programs that use only plain-old 7-bit ASCII
> would have saved zillions of dollars.

True enough. It's unfortunate that the GNAT solution wasn't thought of much 
sooner, nor that we can't seem to find a compatible solution. (But I don't 
think anyone has really tried, either, I don't think this particular issue 
has ever been on the ARG's agenda.)

>> The net effect is that ordering is not very reliable in case-insensitive
>> Unicode identifiers, like Ada's. Cool, huh?
>
> Bleah.

Yeah, Unicode brings its own problems, which are often ignored by its 
proponents. I personally think that programming languages (as opposed to 
program input/output) should stick to 7-bit ASCII, but of course that's 
never been politically possible.

                                              Randy.