Re: html, css, and js modes working together

[Dmitry Gutov]

On 11.02.2017 19:46, Tom Tromey wrote:

> Stefan> To keep `html-mode` as the dispatch function for the various options
> Stefan> (there's web-mode, mumamo's xhtml-mode, psgaml-mode, nxml-mode, ...).
>
> The way I see it is that Emacs should come with something reasonable out
> of the box.  Disabling a feature because it might cause difficulty for
> some other mode that isn't in-tree is both a disservice to users (the
> default Emacs is missing a useful feature) and a maintenance problem
> (who knows what else is out there).

The default Emacs will have this feature if html-rich-mode is associated 
with *.html in auto-mode-alist.

> Also, concretely speaking, these modes will have an easy time adapting.
> In particular the new mode sets 4 local variables:
>
>    (setq-local indent-line-function #'mhtml-indent-line)
>    (setq-local parse-sexp-lookup-properties t)
>    (setq-local syntax-propertize-function #'mhtml-syntax-propertize)
>    (setq-local font-lock-fontify-region-function
>                #'mhtml--submode-fontify-region)
>
> ... so all some other deriving mode would have to do is reset these (and
> maybe not even parse-sexp-lookup-properties, since it's harmless).

How does your buffer-locals approach work?

In mmm-mode, you first call a major mode to get its values of 
indent-line-function and so on. Without them being available after 
calling html-mode, we'd have to hardcode an annoying amount of stuff, 
and become less resilient against renames.