In emacs, how can I add a function to a hook when the function hasn't yet been defined?

Question

I've installed some things from ELPA, namely evil and rainbow-delimiters.

In order to have them run whenever emacs loads, I would put something like:

(evil-mode)
(global-rainbow-delimiters-mode)

In my init.el file.

However, because I installed them from ELPA, they're not loaded until after my init.el has been loaded, and so both symbols are undefined.

As far as I understand, this also prevents me from doing something like

(add-hook 'after-init-hook 'global-rainbow-delimiters-mode)

How can I work around this?

Postscript: This problem was actually caused by me not calling (package-initialize) at the start of my init.el, which would have loaded all of the things installed using packages (evilmode and rainbow-delimiters being just two of them) at the correct time

score 3 · Accepted Answer · answered Jul 25 '12 at 09:09

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Your add-hook solution will work.

There, 'global-rainbow-delimiters-mode is just a name, it will be resolved to the function later, when add-hook is called, and the function will exist by that time.

The ELPA documentation does mention this method, although it seems to consider it as a last resort.

answered Jul 25 '12 at 09:09

Frédéric Hamidi

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So it does. This seems peculiar, I thought I'd tried it, and it didn't work. Perhaps I forgot to byte compile my init file last time – Squidly Jul 25 '12 at 09:12

score 1 · Answer 2 · answered Jul 25 '12 at 18:52

1

AFAIU compiling the init file is not a good idea - but not related so far.

Your hook fails, as it runs after reading the init, but before stuff gets loaded. You need a function to run after load from ELPA.

Try eval-after-load

answered Jul 25 '12 at 18:52

Andreas Röhler

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Why is compiling my init.el a bad idea? – Squidly Jul 26 '12 at 10:03
I've compiled init.el for years. The problem is that if you make changes and forget to compile Emacs will load the old byte-compiled version and you might be confused why it doesn't have your changes. I have added hooks to startup and shut down that ask if I want to compile init.el (if it has changed), so that I never forget to do this. – Ivan Andrus Aug 02 '12 at 07:14

score 1 · Answer 3 · answered Jul 25 '12 at 18:57

1

You can also initialize your packages early with (package-initialize). This will allow you to not put all that code in one hook.

answered Jul 25 '12 at 18:57

Nicolas Dudebout

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In emacs, how can I add a function to a hook when the function hasn't yet been defined?

3 Answers3