Re: [PATCH] Unicode Lisp reader escapes

[Juri Linkov]

>     Support for \u and \U in Emacs Lisp would be good since other _Lisp_ 
> languages
>     support \uXXXX and \UXXXXXXXX as well.  But other Lisp languages support
>     also Lisp notation for Unicode characters.  I think Emacs should support
>     it too.  In this notation Unicode characters are written as #\u3042 or
>     #\u0002a6b2 with the leading hash mark.
>
> We do not in general try to be compatible with Common Lisp on input
> syntax for characters.  So forget this.

The initial `#' character is a valid Emacs hash notation for writing
integers in various bases.  After adding `\uXXXX' it seems reasonable
to add `#\uXXXX' as well.  However, there is one difference: Emacs Lisp
hash notation doesn't use the backslash `\' after `#', e.g. `#x42',
but other Lisps use the backslash in the notation of Unicode characters,
e.g. `#\u3042'.  I have no opinion which notation is better.

>     Also it would be good to support a syntax for named Unicode characters.
>     Common Lisp has the syntax #\euro_sign, and Perl - \N{EURO SIGN}.
>
> I tend to think we should not do this now.
> Does Emacs have a table of these names?

The variable `describe-char-unicodedata-file' points to the file
`UnicodeData.txt' not distributed currently with Emacs.  This could be
done in the emacs-unicode branch.  I think this question should be
considered after the release.

-- 
Juri Linkov
http://www.jurta.org/emacs/