Re: Tree-sitter and major mode inheritance

[Yuan Fu]

> On Nov 20, 2022, at 2:02 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Yuan Fu <casouri@gmail.com>
>> Date: Sun, 20 Nov 2022 01:19:13 -0800
>> Cc: Dmitry Gutov <dgutov@yandex.ru>,
>> emacs-devel@gnu.org,
>> monnier@iro.umontreal.ca,
>> theo@thornhill.no
>> 
>> 
>> 
>>> On Nov 19, 2022, at 11:11 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>>> 
>>>> Date: Sun, 20 Nov 2022 00:03:35 +0200
>>>> Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org,
>>>> monnier@iro.umontreal.ca, theo@thornhill.no
>>>> From: Dmitry Gutov <dgutov@yandex.ru>
>>>> 
>>>> On 19.11.2022 23:49, Yuan Fu wrote:
>>>>> Actually, that’s evidence supporting his preference: js-mode will remain 
>>>>> to be the native implementation, so inheriting from it is exactly as 
>>>>> before. Js-ts-mode will install tree-sitter stuff. And js-base-mode 
>>>>> wouldn’t do much.
>>>> 
>>>> But js-base-mode will be used in auto-mode-alist?
>>> 
>>> NO!!!  auto-mode-alist should keep using js-mode, as it does today.
>>> 
>>> js-base-mode, if we need it, should just be a vehicle for easy sharing of
>>> common stuff between several modes that pertain to the same or similar
>>> languages.  It should NOT be visible to users, so should not appear in any
>>> variables users are likely to customize.
>> 
>> Alright, changing js-mode to ja-native-mode is indeed a bad idea. So this is 
>> what I did: for eg, js-mode, I created js-ts-mode and js-base-mode. Js-mode 
>> and js-ts-mode inherits js-base-mode. Auto-mode-alist has javascript-mode 
>> (that’s what’s in the list right now, I didn’t change it).
>> 
>> If a user wants to use tree-sitter for javascript, they can add 
>> (javascript-mode . js-ts-mode) into major-mode-remap-alist.
> 
> Or manually turn on js-ts-mode.  Or customize auto-mode-alist to have
> js-ts-mode be used in preference to js-mode.  Right?

Right.

> 
>> If someone wants js-mode and js-ts-mode to share the same configuration, he 
>> needs to configure js-base-mode. So js-base-mode isn’t completely invisible. 
> 
> We should not advertise js-base-mode.  If people want to share
> configurations between two modes, they should do that explicitly via their
> own hook function, or via copying the configurations.  (And some of the
> configurations cannot be shared anyway, because the two modes use different
> features for font-lock and indentation.)

Right.

Yuan