From: Brian Candler <lists@...>
Date: 2012-04-18T07:39:34+09:00
Subject: Re: Capital Cyrillic letter in Ruby class name (UTF-8)

Bartosz Dziewoński wrote in post #1057002:
> Vladimir, unfortunately Unicode and internationalisation in general is
> hard. In C code (that's what Ruby is written in), checking whether a
> letter is an ASCII capital one is dead simple. Checking whether is it
> an Unicode capital requires decoding it from whichever variant of UTF
> is was encoded in and looking it up in one oh huge tables defining
> various letter properties to check if it is a capital or not. You
> would probably have to change parsing rules and a lot of internal code
> to make it possible, since capital first letter is the only difference
> between Ruby constant or variable.

Please note that the above is untrue.

ruby 1.9 already does have the functions built-in to determine whether a 
letter is Unicode capital or not; however it explicitly only accepts 
ASCII upper-case for the start of constants. This was a conscious design 
decision. See http://redmine.ruby-lang.org/issues/show/1853
and the other threads linked from that Redmine issue.

If you wanted to allow Unicode capitals as the start of constants, it 
would be a very simple patch to the C source.

What I've managed to gather about upper/lower case handing in ruby 1.9 
is documented at
https://github.com/candlerb/string19/blob/master/string19.rb
(section 11)

Regards,

Brian.

P.S. I'm not saying I think this is a good design decision - in fact I 
think the whole encoding aspect of ruby 1.9 is a dog's breakfast - but 
that's purely my opinion.

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