From: "Štěpán Němec" <stepnem@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: Calling internal-default-process-sentinel from another sentinel?
Date: Wed, 18 Nov 2020 16:12:48 +0100 [thread overview]
Message-ID: <87mtze66mn.fsf@gmail.com> (raw)
In-Reply-To: <jwvk0uibufh.fsf-monnier+emacs@gnu.org>
On Wed, 18 Nov 2020 09:44:18 -0500
Stefan Monnier wrote:
>>> `add-function` is your friend.
>>>
>>> (add-function :around (process-sentinel proc)
>>> (lambda (orig-fun proc state)
>>> (if (one particular case)
>>> (do the thing)
>>> (funcall orig-fun proc state))))
>>
>> Thanks, I've seen similar examples in the code base, but always advising
>> an Elisp sentinel, not 'internal-default-process-sentinel', which is a C
>> function, and IIUC also would/might be called from C (e.g. from
>> status_notify ?). Or is the actual default sentinel some kind of a
>> wrapper?
>
> This is not advising 'internal-default-process-sentinel'. It just
> replaces the sentinel by a new function which often delegates to the
> previous function, whichever that previous function was and without
> affecting that previous function's definition.
>
>> And even for Elisp sentinels, I figured I'd rather avoid advice, as even
>> when using a self-removing piece of advice, it still applies to all
>> (even unrelated) calls of the same sentinel function occurring until the
>> removal. Or am I missing something?
>
> You're confused: this is not an "advice".
Indeed, I hadn't realized that, even though "(process-sentinel proc)"
above would (before the add-function modification) evaluate to
'internal-default-process-sentinel', using `add-function' on that form
really works through `set-process-sentinel' (via a gv place reference)
and is thus different from advising 'internal-default-process-sentinel'
directly.
Thank you!
--
Štěpán
prev parent reply other threads:[~2020-11-18 15:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 13:28 Calling internal-default-process-sentinel from another sentinel? Štěpán Němec
2020-11-18 14:19 ` Stefan Monnier
2020-11-18 14:37 ` Štěpán Němec
2020-11-18 14:44 ` Stefan Monnier
2020-11-18 15:12 ` Štěpán Němec [this message]
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