Re: Converting a Mule character to UCS code point

>>>>> "Hrvoje" == Hrvoje Niksic <[email protected]> writes:

    Hrvoje> * char-ucs, a built-in.  Whatever I do, (char-ucs CHAR)
    Hrvoje> returns nil.  FSF doesn't have it.  Apparently unusable or
    Hrvoje> unfinished.

This works in 21.5.  I don't know what it's defined as in 21.4; since
we have no Unicode tables built-in, it can't work without further support.

    Hrvoje> * char-to-ucs, part of the mule-ucs package

This is really the only current option in 21.4.  An alternative which
would be fast would be to preload tables into C modules (these could
be automatically generated by Lisp programs in 21.5; I use this
approach for latin-unity, for example).  It might require some changes
to 21.4 core (ie, if char-cus is purely a stub, we'd have to implement
it), in which case we'd need Vin's approval.  Probably the way to go
in that case is to remove char-ucs from 21.4 core and implement it as
a module.  I don't know if we can override existing functions from a
module (bad practice, of course, but if the user can't/won't upgrade,
what else is there?)

mule-ucs is deprecated, orphaned, and available only because there's
no reasonable way to get Unicode support in 21.4.

    Hrvoje> * encode-char, also part of the mule-ucs package, and also
    Hrvoje> present in FSF.  The interface is a bit weird
    Hrvoje> (`(encode-char CHAR 'ucs)'), but it seems to work
    Hrvoje> correctly.

Dunno about this.  It's not weird to me.  Presumably you can do that
for any charset and get the external code point.

    Hrvoje> Can any of these be considered stable?

char-ucs is, although if GNU Emacs is standardizing on encode-char, I
guess we have to turn around and piss with the wind.  You should ask
Handa and/or Love.  Here's a trivial restriction of the encode-char
interface for 21.5:

(unless (fboundp 'encode-char)
  (defun encode-char (ch charset)
    (if (eq charset 'ucs)
        (char-ucs ch)
      (error 'wrong-type-argument "encode-char only supports ucs" charset))))


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