From: Michael Albinus <michael.albinus@gmx.de>
To: Brian Merchant <bhmerchant@gmail.com>
Cc: help-gnu-emacs@gnu.org
Subject: Re: How to pass messages between emacs and a Python program? (goal: trying to use emacs as a UI)
Date: Fri, 26 Aug 2016 10:05:15 +0200 [thread overview]
Message-ID: <877fb4gdl0.fsf@gmx.de> (raw)
In-Reply-To: <CAMt_P4=LFb6dLS=Yv4o6zX_+VMPJ-MjjVbKq8+t81d2NNOsxNA@mail.gmail.com> (Brian Merchant's message of "Thu, 25 Aug 2016 15:18:19 -0700")
Brian Merchant <bhmerchant@gmail.com> writes:
> Hi all,
Hi Brian,
> Say I have opened up a file in emacs, and I type in something like:
>
> `x \and \top`
>
> Then, a Python program reads that file, and:
>
> * replaces all `\and` to `∧`
> * replaces all `\top` to `T`
> * it does some thinking on the expression `x \and \top` and decides that
> that is the same as `x`, so will append an `= x`
>
> The final result of all the changes made by the program to the file will
> leave it like so:
>
> `x ∧ T = x`
>
> Okay, so much for what I want. For getting there though:
>
> I don't want the Python program to be constantly polling the file for
> changes (using a `while` loop), and I probably don't want emacs to be
> constantly polling the file for updates (which I know how to do using the
> `auto-revert` command).
>
> Maybe I press some key combination, and then that sends a message to a
> Python script that its time to read the file and make updates and then the
> Python script would message emacs and ask it to update what it is
> displaying in its buffer.
>
> Could this be done?
I have no idea about python and its features in this respect. From the
Emacs point of view, I see two possibilities:
- Use file notifications. Emacs supports file notifications for several
operating systems, like GNU/Linux, *BSD, OS X, Cygnus, MS
Windows. That is, if a file is changed in the file system, an event is
raised by the kernel, and Emacs is able to catch this event and to
run a handler (a Lisp function) bound to this event. If python could
do similar, you have it.
- Use D-Bus messages. This is a communication channel for applications
of different type to talk to each other. Emacs has D-Bus support, and
python has it also (a short web search gave me
<https://dbus.freedesktop.org/doc/dbus-python/doc/tutorial.html>. This
is restricted to operating systems with D-Bus support, mainly
GNU/Linux and Cygwin. Both Emacs and your python program could send a
D-Bus message to the partner, indicating that a file has changed.
> Kind regards,
> Brian
Best regards, Michael.
next prev parent reply other threads:[~2016-08-26 8:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-25 22:18 How to pass messages between emacs and a Python program? (goal: trying to use emacs as a UI) Brian Merchant
2016-08-26 8:05 ` Michael Albinus [this message]
2016-08-26 8:14 ` Thien-Thi Nguyen
2016-08-26 11:51 ` Alexis Roda
2016-08-28 17:10 ` Pascal J. Bourguignon
2016-08-28 19:50 ` Tomas Nordin
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