toggle-markup-hiding stomps on added font-lock-keywords

[hmelman]

I have the following in my markdown-mode-hook:

(font-lock-add-keywords nil '(("\\W@\\w+" . font-lock-variable-name-face))))

Works great when I open a file to highlight things like "@closed". However, using markdown-toggle-markup-hiding removes this highlighting. I might not mind if it only did this while hiding, but using it again to toggle it off doesn't restore my highlighting.

[jrblevin]

Thanks for pointing this out. Currently markdown-mode re-defines font-lock-keywords directly when toggling some settings (like math mode), which is why your addition to the list is lost. A better approach would be for markdown-mode to add and remove the feature-specific elements individually, without modifying the other elements. After I get v2.3 out (I'm waiting a bit in case there are outstanding bugs), I'll work on this for the next version.

In the meantime, possible workarounds are to add your highlighter to markdown-mode-font-lock-keywords-basic instead, which shouldn't be modified after toggling markup, or to advise markdown-reload-extensions and use font-lock-add-keywords as in your hook above.

[jrblevin]

Hopefully this is fixed now, but let me know if you still have issues adding keywords.

[hmelman]

Given the keywords in my original comment, I'm still having the same problem. Am I supposed to be using something else?

[jrblevin]

Sorry about that. It does seem to work if you specify markdown-mode as the mode (to apply globally, say added to init.el outside of a hook) but not when nil is given (which applies only to the current buffer). I wrote the unit test using the former and incorrectly expected the same behavior from the latter. I'm not sure why there is a difference, but I will reopen this and investigate some more.

In other words, this does work for me, but is applied globally rather than to the current buffer only:

(font-lock-add-keywords 'markdown-mode '(("\\W@\\w+" . font-lock-variable-name-face))))

[hmelman]

You're right that setting it that way works. I've changed my markdown-mode customization hooks :)

[jrblevin]

Glad you were able to adjust your configuration. It appears to be fixed now when adding buffer-specific keywords as well.