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bug#25581: 25.1; Incorrect statement in (elisp) `Hooks'
From: |
Stefan Kangas |
Subject: |
bug#25581: 25.1; Incorrect statement in (elisp) `Hooks' |
Date: |
Mon, 24 Aug 2020 11:54:28 -0400 |
Lars Ingebrigtsen <larsi@gnus.org> writes:
> Drew Adams <drew.adams@oracle.com> writes:
>
>> The second sentence here is incorrect:
>>
>> If the variable’s name ends in ‘-function’, then its value is just a
>> single function, not a list of functions. ‘add-hook’ cannot be used to
>> modify such a _single function hook_, and you have to use ‘add-function’
>> instead (*note Advising Functions::).
>>
>> You CAN use `add-hook' to modify such a single-function hook.
>> Nothing prevents you from doing so. And nothing even suggests
>> that you should not. And you have always been able to do so.
I'm not sure the above makes sense. Doesn't it usually work like:
(setq foo-function 'message)
(add-hook 'foo-function 'error) ; should work?
(funcall foo-function) ; => Lisp error: (invalid-function (error message))
> Well, the name -function suggests that you shouldn't.
>
> I think the confusing thing here is that foo-function isn't a hook at
> all -- variables ending with -function are normally not executed with
> run-hooks at all, so using add-hook on such a variable will normally
> break.
>
> So I'm not sure what that section is doing in the Hooks node at all. It
> origin starts here, where unfortunately vc-region-history gives up.
>
> My preference here would be just to remove the paragraph, which is
> pretty confusing.
It sort of makes sense when read next to the paragraph before, doesn't
it? There the concept "abnormal hook" is defined with an explanation of
variables ending in '-functions', and the paragraph about variables
ending in '-function' is written mostly in contrast to that.
I think the confusing thing here is that there are two ways to modify
these single function hooks: setq and add-function.