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Subject: |
Font locking is poorly documented |
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Date: |
Tue, 19 May 2015 15:42:05 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
I was recently urged to use font locking to support a feature in Emacs,
and I must say that I am still confused about how it works even after
reading the Elisp manual several times. The manual has a lot of
low-level discussion of mechanism, but it doesn't explain policy and
since crucial features seem to be undocumented, I'm at a loss as to how
to use it, or how to debug it when it's not working. I finally gave up
and used Google and found cookbook stuff, but I have no idea how or why
it works as well as it does, or why it fails when it does. For example:
http://www.emacswiki.org/emacs/PrettyLambda
gives this example:
(defun pretty-lambdas ()
(font-lock-add-keywords
nil `(("(\\(lambda\\>\\)"
(0 (progn (compose-region (match-beginning 1) (match-end 1)
,(make-char 'greek-iso8859-7 107))
nil))))))
but I can't find documentation explaining why a progn is needed, or why
it must return niil, or why one must use compose-region, or why one must
use it with a single λ rather than just having a λ character there.
One small suggestion: add a section explaining how the above example works.
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--- Begin Message ---
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Subject: |
Re: bug#20613: Font locking is poorly documented |
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Date: |
Thu, 16 Apr 2020 06:13:22 +0200 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Lars Ingebrigtsen <address@hidden> writes:
> I started futzing around with font locking recently (I've never looked
> at it before), and the manual seemed to explain things pretty well
> (although it didn't explain how to test stuff, which is why I added the
> `font-lock-debug-fontify' command).
>
> So is there anything else here that needs to be done, or can this bug
> report be closed?
Since there have been no more comments within 21 weeks, I'm going to
assume that the answer is yes. I'm consequently closing this bug now.
If my assumption is incorrect and this is still an issue, please
reopen the bug report.
Best regards,
Stefan Kangas
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