Re: how to prevent font-lock from messing with a portion of text?

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> > Use put-text-property to add a face to some text using the
>> > `face' property.
>> > Prevent subsequent "erasure" of that highlighting by font-lock.
>> 
>> The `font-lock-face' property was designed specifically for this
>> kind of case.

> 1. That's only for Emacs 22.

Yup.

> 2. It doesn't prevent font-lock from clobbering the highlighted text when
> doing syntactic font lock (e.g. in comments).

It's true that font-lock's own faces take precedence.  But the
font-lock-face property is not clobbered.

> 3. The highlighting is removed when font-lock-mode is turned off.

Again, the lont-lock-face properties are not removed.  But yes, it is made
inactive.

> 4. It won't help with other code (e.g. 3rd library) that happens to use the
> `face' property.

Yup.

> IOW, no, `font-lock-face' property was not at all designed specifically for
> this
> kind of case. Highlight some text, and have it stay highlighted whether or
> not font-lock-mode is on. Have font-lock ignore that text when it does its
> own highlighting.

Well, with those extra conditions, then indeed, no it doesn't quite fit
your bill.

How 'bout:
- use font-lock-mode-hook to move `face' properties to/from a new property
  `persistent-face' when turning font-lock-mode on/off.
- add a font-lock-fontify-region-function so that after fontifying
  the region normally, you scan the region for `persistent-face' properties
  and copy those to the `face' property.

> That's too bad.  How about adding that, after the release?

I'm not interested in coding it up because I don't see a need for it, but if
someone provides a clean patch, I don't see any reason why I'd oppose it.

> From what you say, it sounds as if that whole passage about that property
> should be stated in terms of jit-lock only. And there should be a cross
> reference to the place where jit-lock is introduced.

Yes, that's probably right.


        Stefan