Fwd: A TAB operation reform question.

[Vladimir Nikishkin <lockywolf@gmail.com>]

I am sorry for "forwarding" an email, but I initially thought that
"help-gnu-emacs" would be more appropriate.

But still, I would like to ask what Emacs developers think about this
issue. Would it be possible to repurpose TAB from "sometimes TAB,
sometimes indent, sometimes complete", to a more general-purpose dwim
framework?

Vladimir Nikishkin <lockywolf@gmail.com> writes:

> Hello, Emacs users and developers
>
> I would like to ask if a reform to the way TAB (C-i) works has been
> considered? And if "yes", then how hard would it be to implement it?
>
> The motivation is the following:
>
> The way TAB works at the moment is peculiar.
>
> There is this "indent-for-tab-command", which either indents, or inserts
> a tab-character, or completes... unless "tab-always-indent" is set to
> some special value, but there are mode-specific
> modename-tab-always-indent, but they are also sometimes ignored. Also,
> org-mode overrides it with "org-cycle", and perhaps, other modes do too.
> Also, "tab" is considered to be "the place somehow close to completion
> functions", so M-C-i==M-TAB is "ispell-complete-word", and a lot of
> other packages try to make their completion somehow close to TAB.
>
> This looks a bit like a mess, partly because TAB is almost universally
> seen as a "dwim" entry point, but it is not officially so in Emacs.
>
> Could there be an alternative protocol? Could TAB be make a DWIM entry
> point "officially"?
>
> In particular, could it be possible to make a "hard-switch" variable
> "tab-always-inserts-tab", which would be the opposite of
> "tab-always-indent", but simpler, and it would be possible to override
> it in the major modes, thus making "c-tab-always-indent" unnecessary.
>
> If tab-always-inserts-tab is set to nil, TAB (for example) would be
> looking in some customizable list of functions, say
> "tab-dwim-list-functions", and run each function until some does not
> return non-nil. The default list could be something like
> (indent-if-possible indent-comment-if-possible hs-fold-if-possible
> complete-if-possible insert-tab).
> Using TAB with a prefix-argument would always insert a TAB. (which would
> be an exception to the rule "default prefix argument is 4", but I think
> it would be understandable.).
>
> This way, instead of rebinding tab to org-cycle, org-mode could prepend
> "org-cycle" to this list, or make it the only member of the list, but
> this would still allow the users to plug in custom dwim functions
> further into the list, such as ispell-word (not completion), jump
> between table cells, and such.


-- 
Your sincerely,
Vladimir Nikishkin (MiEr, lockywolf)
(Laptop)