From: Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: Lars Ingebrigtsen <larsi@gnus.org>
Cc: Leo Liu <sdl.web@gmail.com>, 19066@debbugs.gnu.org
Subject: bug#19066: 25.0.50; nadvice and interactive-form
Date: Sun, 30 May 2021 13:26:52 -0400 [thread overview]
Message-ID: <jwvwnrgw3c7.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <87r1hry5dq.fsf@gnus.org> (Lars Ingebrigtsen's message of "Fri, 28 May 2021 04:11:13 +0200")
Lars Ingebrigtsen [2021-05-28 04:11:13] wrote:
> Leo Liu <sdl.web@gmail.com> writes:
>> 1. Start emacs and load a file with these lines:
>>
>> (advice-add 'just-one-space :before #'change-interactive-form)
>> (defun change-interactive-form (&optional x y)
>> (interactive (list 1 1))
>> (princ (list x y)))
>>
>> M-x just-one-space prints (1 nil)
>>
>> 2. Start emacs and load a file with these lines:
>>
>> (defun change-interactive-form (&optional x y)
>> (interactive (list 1 1))
>> (princ (list x y)))
>> (advice-add 'just-one-space :before #'change-interactive-form)
>>
>> M-x just-one-space errs: apply: Wrong number of arguments: (0 . 1), 2
>
> So whether this works depends on whether `change-interactive-form' is
> defined or not when `advice-add' is run? (The only difference here is
> the order.)
> Perhaps Stefan has some insights here; added to the CCs.
[ Side note: the correct/desired behavior is the one described by (2),
i.e. it should signal a "Wrong number of arguments" (tho after
printing (1 1)). ]
`advice-add` creates a new function object which is a "composition" of
the old function and the advice that's added to it.
In the case where `change-interactive-form` is defined later, one way to
make this work right would be for `advice-add` to put some kind of
"watcher" on (symbol-function 'change-interactive-form) to recompute the
interactive form of the "composed function".
Another way would be to make the interactive form of the "compose
function" more dynamic: make it re-checks the interactive form of every
advice function every time. That's probably the better option.
Stefan
next prev parent reply other threads:[~2021-05-30 17:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-16 10:00 bug#19066: 25.0.50; nadvice and interactive-form Leo Liu
2021-05-28 2:11 ` Lars Ingebrigtsen
2021-05-30 17:26 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2021-05-31 5:43 ` Lars Ingebrigtsen
2021-05-31 12:49 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
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