[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#20436: 25.0.50; syntax-multiline not documented
From: |
Stefan Monnier |
Subject: |
bug#20436: 25.0.50; syntax-multiline not documented |
Date: |
Tue, 13 Jul 2021 14:11:36 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
Lars Ingebrigtsen [2021-07-13 19:57:55] wrote:
> Tom Tromey <tom@tromey.com> writes:
>> I noticed some code in syntax.el for the syntax-multiline property.
>> This doesn't seem to be documented anywhere, but I think it should be.
>
> Looking at this:
>
> (defun syntax-propertize-multiline (beg end)
> "Let `syntax-propertize' pay attention to the syntax-multiline property."
> (when (and (> beg (point-min))
> (get-text-property (1- beg) 'syntax-multiline))
> (setq beg (or (previous-single-property-change beg 'syntax-multiline)
> (point-min))))
> ;;
> (when (get-text-property end 'syntax-multiline)
> (setq end (or (text-property-any end (point-max)
> 'syntax-multiline nil)
> (point-max))))
> (cons beg end))
>
> And some of the usage sites... I'm still not quite sure what the
> semantics here are. :-) I've added Stefan M to the CCs; perhaps he can
> explain and I'll write something up for the manual?
Its semantics is implemented by `syntax-propertize-multiline` (whose
docstring speaks volumes ;-), so the property is only effective after
you've added `syntax-propertize-multiline` to
`syntax-propertize-extend-region-functions`.
What it does is cause `syntax-propertize` to treat the marked text such
that it will always be propertized in a single call rather than two or
more separate calls.
The most common use for it is when the syntax to use for "FOO" depends
on some *later* text "BAR": by placing this property over the whole of
"FOO...BAR" you make sure that any change of "BAR" will cause the
syntax of "FOO" to be recomputed.
Stefan