Hi Matt,
2018ko azaroak 6an, Matt Price-ek idatzi zuen:
>
> Hi,
>
> I was writing a function to quickly post the ocntents of subtrees to the
> Canvas Learning Management System. I was trying to strip down the exported
> HTML to an absolute minimum and had forgotten about the body-only paramter
> to org-export-as (!!). So, my solution was to try to rebind
> 'org-html--build-meta-info to always just return "". However, I can't
> seem to do it properly and I'm wondering if someone can help me figure out
> what's wrong. It's my first time using cl-flet! And I know there are
> various approaches, but I odn't understnad whyt this is notworking, when
> for instance, this does work for me:
>
> (cl-flet ((+
> (lambda (&rest args) (message "no plus!"))))
> (+ "whoops"))
> ;; "no plus!"
>
> Meanwhile, here's my non-functional code:
Quoting from the info page (info "(cl) Function Bindings"):
The bindings are lexical in scope. This means that all references
to the named functions must appear physically within FORMS.
I believe that you can accomplish what you are trying to do with:
(cl-letf (((symbol-function 'org-html--build-meta-info)
(lambda (&rest args) "")))
your-code-here)
You could also do something like:
(let ((my-advice (lambda (&rest _) "")))
(advice-add 'org-html--build-meta-info :override my-advice)
(unwind-protect
(progn
your-code-here)
(advice-remove 'org-html--build-meta-info my-advice)))
(Why do I think this is better, despite being more verbose? Advice-add
is specifically designed to change the binding of functions at runtime,
and so it does some specialized things that cl-letf doesnʼt do. This in
turn means that it should be a more robust way of accomplishing the
desired outcome.)
--
Aaron Ecay
