GNU bug report logs - #49822
28.0.50; python-shell-send functions show no output

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From: Augusto Stoffel <arstoffel <at> gmail.com>
To: "Barton, Mark" <Mark.Barton <at> disney.com>
Cc: Andy Moreton <andrewjmoreton <at> gmail.com>, emacs-devel <at> gnu.org, Andreas Schwab <schwab <at> linux-m68k.org>, Stefan Monnier <monnier <at> iro.umontreal.ca>, 49822 <at> debbugs.gnu.org, Michael Albinus <michael.albinus <at> gmx.de>, Lars Ingebrigtsen <larsi <at> gnus.org>
Subject: bug#49822: master e32c7d2: Change Python eval to send directly instead of using temporary files
Date: Tue, 07 Sep 2021 19:37:41 +0200

[Message part 1 (text/plain, inline)]

On Mon,  6 Sep 2021 at 13:53, Andreas Schwab <schwab <at> linux-m68k.org> wrote:

> On Sep 06 2021, Michael Albinus wrote:
>
>> Andreas Schwab <schwab <at> linux-m68k.org> writes:
>>
>>>>> Okay, so is the TTY line length limit of the OS available in Lisp
>>>>> somewhere?  Otherwise, can we at least trust that 1024 is the universal
>>>>> lower bound?
>>>>
>>>> On systems with a POSIX shell:
>>>>
>>>> (let ((default-directory "/"))
>>>>   (read (shell-command-to-string "getconf LINE_MAX")))
>>>
>>> LINE_MAX has nothing to do with the tty line discipline.
>>
>> I'll never learn it :-(
>>
>> We've discussed this issue some years ago already. IIRC, the outcome was
>> to use "getconf PIPE_BUF /" instead.
>
> Neither has PIPE_BUF.
>
> Andreas.

Okay then. Since there seem to be no better alternatives, I have
attached a new patch reducing the limit to a hard-coded 1024 bytes.  If
some day someone adds a variable specifying a more precise limit, then
we can change this.

I have also rearranged things a bit so that the setup code is sent to
the inferior process just once, rather than of on every call to
`python-shell-send-string'.  This way, the smaller line length limit
doesn't increase too much the use of temp files, which, as I mentioned,
is slow over ssh.

It would be great if someone with access to a BSD-like OS could test
this.  I can only test locally on Linux and over ssh between Linux
machines.

PS: I have some more suggestions around the Python shell.  Is the ideal
workflow to keep creating bugs with a small patch to each improvement,
or do you prefer to review a larger collection of changes bundled
together?

[0001-Reduce-limit-of-line-length-sent-to-the-Python-infer.patch (text/x-patch, attachment)]

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