Re: A proposal for the future of open-paren-in-column-0-is-defun-start.

[Dmitry Gutov <dgutov@yandex.ru>]

Hi Alan,

On 05.04.2020 16:47, Alan Mackenzie wrote:
> `syntax-open-paren-in-literal' would be applied throughout the buffer
> when it is first loaded into Emacs, and would be kept up to date by
> "super before/after-change-functions".  (These functions would be called
> at buffer changes regardless of the value of inhibit-modification-hooks.
> We would want some way of inhibiting them being called on a change of
> text properties, for efficiency's sake).
> 
> With this mechanism in place, o-p-i-c-0-i-d-s could safely be left
> enabled, for speed's sake, without causing the all too familiar bugs in
> CC Mode.
> 
> What do people think?

While I'm not convinced that syntax-ppss is a significant bottleneck 
now, nor crazy about the idea of yet another kind of hooks which will 
have to scan the whole buffer after every buffer change, I say go for 
it. :-)

The proposed approach seems easy enough to implement, and then you could 
do some real-world benchmarks (something like: 1. scrolling 50 times, 2. 
typing new code in a big file, 3. simply visiting a big file), compare 
and see what improved, and what didn't, and by how much. Then we'd have 
something to discuss, at least.