Proposed Expansion of Grapheme Clusters to Whole Aksharas - Implementation Issues

[Richard Wordingham via Unicode]

On Fri, 22 Dec 2017 17:44:39 +0200
Eli Zaretskii via Unicode <unicode at unicode.org> wrote:

> You can always delete a codepoint at a given position in Emacs,
> specifying the position by its number, but there are no user-level
> commands to conveniently allow doing that in the middle of a grapheme
> cluster.
> 
> It was never requested nor deemed necessary to provide such a
> capability.

Kenichi Handa provided such a capability for Emacs, but it has not been
accepted for the main line.  I am using a version of his code which
he kindly provided for my own editing.  The discussion is available at
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=20140 .  The figure
attached to it shows stepping through a 7-character (6 graphic and one
'invisible' stacker) akshara.

> Normally, replacing some portions of a grapheme cluster
> produces a radically different display, so it makes more sense to
> delete everything and start anew.

Non sequitur.

> Deleting individual codepoints by
> Backspace is useful for accents and diacritics, which generally are
> input after the base characters, so that is provided.

Don't forget that a cluster can be a large constellation of
characters.

Richard.