Re: not quite understanding input methods

[Perry E. Metzger]

On 9/1/21 03:23, Juri Linkov wrote:

> Emacs 28 has the input method "Compose" corresponding to XKB's Compose
> in leim/quail/compose.el, but many useful key sequences in this
> input method don't work because of the artificial limitation
> to ASCII-only chars in read_char.
I've been looking at this a bit. If you simply lift the limitation in 
read_char everything downstream fails. It appears that the limitation is 
partially caused by the fact that quail.el expects to be able to create 
dense keymaps of size limited to 255, though that might not be the only 
problem.  Note that fixing this won't be overly difficult, but it would 
need to be fixed in anything that can supply a `input-method-function` 
that is hooked by read_char.

(BTW, as a pure aside: why aren't keymaps hash tables? Is that purely 
historical?)

(FYI, I fear that after the last few days of reading I may be the expert 
on how all of this works, which is terrifying because I feel completely 
lost in the code. It's a maze. It's pretty rare that I see a part of 
Emacs that I feel should be nuked from orbit, but the input subsystem 
feels that way; a rewrite would be required to make it actually 
comprehensible, but a rewrite would also break enormous amounts of stuff 
that people depend on.)


Perry