Re: Tree-sitter integration in python.el

[Augusto Stoffel <arstoffel@gmail.com>]

On Fri,  7 Oct 2022 at 15:10, Yuan Fu wrote:

>> On Oct 7, 2022, at 3:03 AM, Augusto Stoffel <arstoffel@gmail.com> wrote:
>> 
>> On Fri,  7 Oct 2022 at 01:25, Yuan Fu wrote:
>> 
>>> Yeah, with tree-sitter, fortifying types is trivial. In fact all types
>>> should be fortified already. (I tested with some simple examples.)
>>> Should we provide some variables to toggle fontification for different
>>> things? Like python-fontify-type/f-string/assignment/built-in/etc.
>> 
>> Looking at the screenshots posted a few messages back, which are VERY
>> busy, I would really appreciate an option to disable a few fontification
>> rules or, conversely, disable all but a few of them.  Ideally, this
>> should be done through a generic mechanism that works across major
>> modes.
>> 
>> Have you seen the new `font-lock-ignore' option?  Tree-sitter could
>> provide something similar (and much better/less hacky).
>
> The complaint for font-lock-maximum-decoration is that it’s obscure
> and too corse-grained.

To me, the biggest problem with font-lock-maximum-decoration is that few
major modes bothered to implement levels.

> So my idea is for each major mode to provide fined-grained controls
> like python-fontify-type/f-string/assignment/built-in/etc.  And
> tree-sitter makes it easy to implement this kind of toggle.

Given the lack of success of font-lock-maximum-decoration, I don't see
this being implemented by many major modes.  Also, if the idea does take
traction, it will lead to a proliferation of user options that is hard
to use effectively -- if someone doesn't want to fontify built-ins in
Python, they probably don't want it in other languages either, so they
need to set a similar option for N languages.

> But I guess a global control is also nice, I can make tree-sitter
> respect font-lock-maximum-decoration, in addition to the fined grained
> local-control.
>
> Since we are designing a new system, I don’t think we need to resort
> to the likes of font-lock-ignore.

It's exactly the opposite: since you are designing a new systems, you
can create a much nicer customization mechanism on the lines of
font-lock-ignore.  For instance, one could select fontification rules
based on the affected node type.

The “decoration levels” feature can then build up on this, with the
advantage that it would be consistent across languages and require no
extra effort from the major mode developer.