bug#72460: [patch] add commands for setting keyboard translations interactively

[Eli Zaretskii <eliz@gnu.org>]

Ping! Hugo, please respond.

> Cc: 72460@debbugs.gnu.org
> Date: Sat, 14 Sep 2024 10:38:04 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> Hugo,
> 
> Any followups to Stefan's comments?
> 
> > Cc: 72460@debbugs.gnu.org
> > Date: Sat, 31 Aug 2024 09:56:58 -0400
> > From:  Stefan Monnier via "Bug reports for GNU Emacs,
> >  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> > 
> > >> > +(defcustom key-translate-selection-function #'key-select-translation
> > >> Do we need this?
> > > Short answer: yes.
> > >
> > > I wanted a way for users to customise how the current translation
> > > pairs are presented when they choose one to remove. The initial
> > > motivation was that some users might want to customise the formatting
> > > of the pairs; "X -> Y" vs "X → Y" vs "X Y" etc. (I'm the sort of user
> > > who cares about this sort of thing a lot).
> > 
> > Rewriting a whole new `key-translate-selection-function` function for
> > that is not significantly easier than rewriting a whole new
> > `key-translate-remove`, so I think this is firmly in the overengineering
> > side of the camp.
> > 
> > > I also envisage that many users will want to use/expect
> > > completing-read (as in the default) and will want the from/to elements
> > > vertically aligned (again, I am this user).
> > 
> > AFAICT, you're the first user to propose this functionality in Emacs's
> > 40 years life, so I wouldn't bet on "many users".
> > 
> > BTW, I just noticed:
> > 
> > > +    ;; Populate collection
> > > +    (map-char-table format-func keyboard-translate-table)
> > > +    (get-text-property 0 'key-translate-from
> > > +                       (completing-read "Key Translation: " collection))))
> > 
> > You can't trust `get-text-property` here (especially since you don't
> > even force `completing-read` to `require-match`).
> > Instead you should do something like `key-parse`.
> > 
> > > I think here I was just copying the current calling convention for the
> > > existing (non-interactive) `key-translate'. Its docstring reads:
> > >
> > >> Both FROM and TO should be specified by strings that satisfy
> > >> `key-valid-p'.
> > >
> > > I sort of assumed someone cleverer than me had a good reason.
> > 
> > I suspect this is because we expect this function to be called from
> > a `~/.emacs` with a literal constant as argument, and we've tried to
> > unify on using the "KBD" syntax for those cases, since it's a friendlier
> > syntax than the "vector of events" where you need to distinguish between
> > symbols and chars with/without modifiers.
> > 
> > Since the arg of `key-translate` can be only a valid char (rather than
> > any arbitrary key potentially with modifiers), the argument is much less
> > strong, but my guess is that it was uniformity.
> > 
> > In the case of `key-translate-remove` I don't expect the arg to be
> > a literal constant in the code, so "nice/uniform syntax to write the
> > argument value" shouldn't be a concern.  🙂
> > 
> > 
> >         Stefan
> > 
> > 
> > 
> > 
> > 
> 
> 
> 
>