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RE: 1) (elisp) `Advising Named Functions', 2) search filtering example
From: |
Drew Adams |
Subject: |
RE: 1) (elisp) `Advising Named Functions', 2) search filtering example |
Date: |
Mon, 17 Oct 2016 10:05:34 -0700 (PDT) |
> > I think that is wrong also. `add-hook' _can_ be used to modify a
> > _single function hook_. And the doc of `add-hook' tells you so,
> > in its last line - `C-h f add-hook':
> >
> > ...
> > If HOOK's value is a single function, it is changed to a list of
> > functions.
>
> If you do this, then you will break the callers, which expect the
> value of this variable to be a single function.
Tell that to the doc string for `add-hook', which has said what it
says in this regard for a very long time.
What has changed (what is new) is that this was added to node `Hooks':
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::).
And that is clearly false ("cannot be used" - it _can_ be so used).
This is what that doc used to say (e.g. Emacs 23.4):
By convention, abnormal hook names end in `-functions' or
`-hooks'. If the variable's name ends in `-function', then
its value is just a single function, not a list of functions.
There has thus also (apparently) been a change in policy here.
Whereas, before, this doc just let you know about the _naming
convention_ for a hook whose value is a single function, the
changed doc says (incorrectly) that you cannot use `add-hook'
with it.
I think that callers of such a hook should _use it as a hook_,
and not necessarily expect that the value is a single function.
Callers of a hook can, and should, I think, use one of the
`run-hook*' functions. And there too you will note that the
doc _explicitly_ talks about the non-list, single function case.
`C-h f run-hooks':
If a hook symbol has a non-nil value, that value may be a
function or a list of functions to be called to run the hook.
If the value is a function, it is called with no arguments.
If it is a list, the elements are called, in order, with no arguments.
`C-h f run-hook-with-args':
The value of HOOK may be nil, a function, or a list of functions.
Call each function in order with arguments ARGS.
(It used to say this:
If HOOK has a non-nil value, that value may be a function
or a list of functions to be called to run the hook. If the
value is a function, it is called with the given arguments
and its return value is returned. If it is a list of functions,
those functions are called, in order, with the given arguments ARGS.)
`C-h f run-hook-with-args-until-failure':
The value of HOOK may be nil, a function, or a list of functions.
Call each function in order with arguments ARGS, stopping at the
first one that returns nil, and return nil.
`C-h f run-hook-with-args-until-success': similar.
So do we have changes in policy wrt using hooks, or not?
(If yes, why?) Which doc needs to be fixed?
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, (continued)
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Noam Postavsky, 2016/10/17
- RE: 1) (elisp) `Advising Named Functions', 2) search filtering example, Drew Adams, 2016/10/17
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Noam Postavsky, 2016/10/17
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Stefan Monnier, 2016/10/17
- RE: 1) (elisp) `Advising Named Functions', 2) search filtering example, Drew Adams, 2016/10/17
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Stefan Monnier, 2016/10/17
- RE: 1) (elisp) `Advising Named Functions', 2) search filtering example, Drew Adams, 2016/10/17
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Stefan Monnier, 2016/10/17
- RE: 1) (elisp) `Advising Named Functions', 2) search filtering example, Drew Adams, 2016/10/17
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Noam Postavsky, 2016/10/17
- RE: 1) (elisp) `Advising Named Functions', 2) search filtering example,
Drew Adams <=
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Stefan Monnier, 2016/10/17
- RE: 1) (elisp) `Advising Named Functions', 2) search filtering example, Drew Adams, 2016/10/17
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Stefan Monnier, 2016/10/17
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Richard Stallman, 2016/10/18
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Eli Zaretskii, 2016/10/19
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Richard Stallman, 2016/10/19
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Stefan Monnier, 2016/10/19
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Eli Zaretskii, 2016/10/20
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Eli Zaretskii, 2016/10/20
- Re: 1) (elisp) `Advising Named Functions', 2) search filtering example, Richard Stallman, 2016/10/20