Re: antlr-mode.el - need some support by python.el

[Dmitry Gutov]

On 03/02/2015 07:23 AM, Stefan Monnier wrote:

> Why?  This "code which operates on this region" can very easily want to
> call indent-according-to-mode or syntax-ppss to do its job.

Maybe we can say that code inside narrowing is only allowed to call 
`generic' features, which may or may not perform widening themselves.

For indent-according-to-mode, see my previous message.

The uses of `syntax-ppss' are harder to classify, but for font-lock we 
at least have font-lock-dont-widen. It's hard for the "inner" code to 
know whether it's allowed to widen, so when in doubt, it probably shouldn't.

But to keep the current code everywhere more or less unchanged, we can 
come from the other side and use an extra-flexible solution: introduce 
`widen-function' or `widen-bounds'. The former would be the function 
`widen' would delegate to from now on (and the interested parties would 
be able to bind it to #'ignore), and the latter would be the maximum 
bounds the new implementation of `widen' would widen to.