Re: Unifying "foo-mode"s and "foo-ts-mode"s

[Eli Zaretskii <eliz@gnu.org>]

> From: Philip Kaludercic <philipk@posteo.net>
> Cc: emacs-devel@gnu.org,  casouri@gmail.com
> Date: Fri, 30 Dec 2022 15:20:35 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I think we want to let the users say, for every single mode, whether
> > they want to use the treesit-enabled variant or not, and also to be
> > able to go back to the non-treesit mode later in the session (e.g., if
> > they don't like the results).  A list is not a convenient means for
> > doing so.
> 
> How come?  When presented in the customise interface we could make it
> out to be a set where users get to pick what modes they want.  And
> updating the value works fine whenever a mode is re-applied.

The need to manipulate a list when all I want is to turn on or off a
single feature is a nuisance.

> > What does this mean in user-facing behavior?  Does it mean that if
> > tree-sitter is not available, or the Python grammar fails to load for
> > some reason, Emacs will silently fall back to the "traditional"
> > python-mode?  If so, I don't think this is what we want.  The failure
> > for loading tree-sitter support should not be silent.
> 
> I am not sure why?  Tree-sitter is an improvement in that it allows
> Emacs to provide better highlighting and knowledge of the syntax, but in
> the end it isn't something you think about actively -- or even should
> have to think about.This is all backend stuff that doesn't interest the
> casual user.  I strongly believe that the principle of "graceful
> degradation" is the right approach here.

You assume a lot here.  First you assume that everyone will see
tree-sitter as an improvement -- that is not a given, and moreover can
vary from language to language.  Second, you assume that whether
tree-sitter is used doesn't interest the user -- again, not a given.
Especially since we currently ask users to install the grammar
libraries.

Your strong beliefs in this matter are noted, but I don't share them,
and think that we should collect actual user experience before we make
such significant decisions.

Btw, you were previously expressing concerns about the risk of
committing to some strategy too early -- well, I think what you
propose will commit us to some strategy much more than what we have
now.

> And in the end, if the tree-sitter support is hidden behind new modes, I
> know already that most people (who don't use starter packs) will never
> notice their existence and won't make use of the support.  There are
> people still using linum-mode, even though display-line-numbers-mode has
> been around for a while.

There's a world of difference between tree-sitter support and a minor
feature such as display-line-numbers-mode.  Just look at Reddit as one
example.

I'm sure tree-sitter will be very visible to users.

> > These are exactly the aspects of the behavior we discussed a month
> > ago, and what we have now is the result of those discussions.
> 
> Could you point me to the thread(s)?  I did not have the time to follow
> the threads in detail a month ago.

Sorry, I don't have them ready and cannot afford looking them up: too
many things on my plate.  Perhaps someone else will do that.