Re: [PATCH] Unicode Lisp reader escapes

[Oliver Scholz]

Richard Stallman <address@hidden> writes:

>     > What does "fragmentation" mean?  I do not recall seeing that term
>     > in this context.
>
>     It's the opposite of unification. In this context it can mean two
>     different things:
>
> Thanks.
>
>     1. Undo the effects of `unify-8859-on-decoding' mode. That is, wenn
>        decoding some encodings like cyrillic or some ISO 8859 encodings,
>        then decode them to characters from appropriate mule charsets (e.g.
>        `greek-iso8859-7') rather than to characters from the charset
>        `mule-unicode-0100-24ff'. This is the default.
>
> Don't you mean "Don't perform the actions of `unify-8859-on-decoding'
> mode?"

Both actually. This is what Emacs does by default. But there's also a
function `ucs-fragment-8859' that, when called with its second
argument non-nil, reverses the effects of unification on decoding.
This is how `unify-8859-on-decoding-mode' is implemented:

(define-minor-mode unify-8859-on-decoding-mode
  "Set up translation-tables for unifying ISO 8859 characters on decoding.
[...]"
  :group 'mule
  :global t
  :init-value nil
  (if unify-8859-on-decoding-mode
      (ucs-unify-8859 nil t)
    (ucs-fragment-8859 nil t)))


>     2. When decoding UCS encodings like UTF-8, decode characters from
>        certain reperoires, e.g. "Greek", to different mule charsets like
>        `greek-iso8859-7'. The default is to decode them all to characters
>        from `mule-unicode-0100-24ff'. A user can turn this behaviour on by
>        customizing `utf-fragment-on-decoding'.
>
> That one isn't relevant to the problem we need to solve now.

Sorry, I was not aware that this decision was definitive.


    Oliver
-- 
Oliver Scholz               29 Floréal an 214 de la Révolution
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