Re: Extending define-derived-mode

[Yuan Fu]

> On Jun 5, 2023, at 4:33 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Yuan Fu <casouri@gmail.com>
>> Date: Mon, 5 Jun 2023 00:31:02 -0700
>> Cc: Stefan Monnier <monnier@iro.umontreal.ca>,
>> emacs-devel <emacs-devel@gnu.org>,
>> Mickey Petersen <mickey@masteringemacs.org>,
>> Theodor Thornhill <theo@thornhill.no>,
>> dgutov@yandex.ru
>> 
>>> For users to be able to share stuff like electric-quote-local-mode
>>> we'd need to rewrite those supporting modes to allow that.  When one
>>> of the two modes uses regexps and syntax tables, whereas the other
>>> uses treesit-based parsers, this is not a trivial task.  I invite you
>>> to audit the various electric modes we have and see how many of them
>>> can be shared with minimum effort between non-TS and TS modes.
>> 
>> I’m talking about sharing the sharable config. Electric modes already work 
>> the same in ts and non-ts modes: electric-pair-mode and electric-quote-mode 
>> inserts matching pairs and quotes and aren’t affected by tree-sitter, 
>> electric-indent-mode uses the standard indent-line-function which both ts 
>> and non-ts modes confront to. Is there any other electric modes?
> 
> For one prominent example, see the node "Electric Keys" in the CC Mode
> manual, and the minor modes described in "Minor Modes" there.

Ok, but they are CC mode’s features, not Emacs-wide features like 
electric-quote/pair/indent-mode.

> 
>> Also, ts modes generally have the same syntax table as non-ts modes. So if 
>> some package uses the syntax table they are largely not affected either.
> 
> But it makes little sense to me to have part of a mode use our syntax
> tables, and another part use the results of parsing the code by a
> parser library.  I can guarantee inconsistencies.

Not really used by the mode itself, but some generic third-party package. 
Having correct information in the syntax table is better than not. Also some ts 
modes enhances the syntax table information, making it more accurate, by adding 
appropriate syntax-table text property on some chars, like the angle brackets 
in C++ and Rust.

Yuan