From: Jim Porter <jporterbugs@gmail.com>
To: Milan Zimmermann <milan.zimmermann@gmail.com>, 59469@debbugs.gnu.org
Subject: bug#59469: Adding a simpler duplication of the issue
Date: Mon, 21 Nov 2022 20:56:16 -0800 [thread overview]
Message-ID: <136fc764-48a4-4b03-c520-bd6ef16d9a50@gmail.com> (raw)
In-Reply-To: <CAEc2VK0yJf_2S88WSRtiSoXGQkW2jHVJCYmQsH+3sAvFHrAANA@mail.gmail.com>
On 11/21/2022 6:50 PM, Milan Zimmermann wrote:
> A simpler duplication shows the issue is below.
[snip]
> Same bug: After the call to non-elisp program, /usr/bin/gzip, a
> previously exported variable bbb (exported inside the block) is nullified.
I'm not entirely sure, but I have a suspicion that this is due to
Eshell's deferred commands. Deferred commands tell Eshell to stop
processing synchronously and yield to the rest of Emacs. It's a way of
keeping long-running commands (e.g. external processes) from hanging the
rest of Emacs.
Unfortunately, the logic to do this (see 'eshell-do-eval') was written
before lexical binding was added to Emacs Lisp, and I think this is the
cause of quite a few subtle bugs with Eshell command evaluation. Fixing
that is bug#57635, which would leverage the generator.el internals to do
this.
Of course, I could be wrong. This is reaching well past my comfort zone
for Emacs Lisp, but this sure seems like an issue with 'eshell-do-eval'.
I'd certainly like to fix this one day, since it's blocking a few other
things I want to do in Eshell, but I think it'll be a pretty big project.
next prev parent reply other threads:[~2022-11-22 4:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-22 2:04 bug#59469: 29.0.50; Eshell "for" loop: Calling a non-lisp command (example: /usr/bin/tail) sets the variable exported in the {} block of "for var in list {}" to nil Milan Zimmermann
2022-11-22 2:50 ` bug#59469: Adding a simpler duplication of the issue Milan Zimmermann
2022-11-22 4:56 ` Jim Porter [this message]
2022-11-22 7:18 ` Milan Zimmermann
2023-01-25 1:39 ` Jim Porter
2023-01-29 6:55 ` bug#59469: 29.0.50; Eshell "for" loop: Calling a non-lisp command (example: /usr/bin/tail) sets the variable exported in the {} block of "for var in list {}" to nil (was: Adding a simpler duplication of the issue) Jim Porter
2023-02-10 5:44 ` Jim Porter
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