Comint and windows

Comint and windows

[Sam Halliday]

Hi all,

I've been forced to use Windows at work and I'm finding some of my modes don't work.

One mode that is not working for me is sbt-mode:

https://github.com/hvesalai/sbt-mode/issues/33

It is a pretty standard implementation of a major mode that talks to an external process via comint. But it looks like commands typed in emacs are not being sent to the process.

Are there any known gotchas with writing these sorts of modes to run on windows?

Best regards, Sam

Re: Comint and windows

[Eli Zaretskii]

> Date: Thu, 5 Nov 2015 00:12:51 -0800 (PST)
> From: Sam Halliday <sam.halliday@gmail.com>
> 
> I've been forced to use Windows at work and I'm finding some of my modes don't work.
> 
> One mode that is not working for me is sbt-mode:
> 
> https://github.com/hvesalai/sbt-mode/issues/33
> 
> It is a pretty standard implementation of a major mode that talks to an external process via comint. But it looks like commands typed in emacs are not being sent to the process.
> 
> Are there any known gotchas with writing these sorts of modes to run on windows?

Yes.  It's likely a buffering issue.  Windows doesn't have pty's, so
communications with subprocesses is via pipes, which fail the isatty
test, and so the subprocess most probably buffers its standard
streams because it doesn't sense that they are connected to a terminal
device.

Try invoking the subprocess in a way that disables buffering of
stdin/stdout on the subprocess's side.  It could be some command-line
switch or maybe some command you need to invoke immediately after
invoking the subprocess.  (If there's no such option, ask the
developers to provide one, or hack the code yourself.)

Re: Comint and windows

[Jeffrey DeLeo]

I used to use emacs regularly on Windows, along with cygwin. I no longer
do. I did use shell and other processes successfully, this is from my
.emacs on Windows. I can't say what is relevant anymore, though.

#+BEGIN_SRC emacs-lisp

  (defun my-shell-setup ()
         "For Cygwin bash under Emacs 20"
         (setq comint-scroll-show-maximum-output 'this)
         (make-variable-buffer-local 'comint-completion-addsuffix))

  (setq shell-file-name "bash")
  (setenv "SHELL" shell-file-name) 

  (setq explicit-shell-file-name shell-file-name) 
  (setq explicit-shell-args '("--login" "-i"))
  (setq shell-command-switch "-ic")
  (setq explicit-bash-args '("--noediting"))
  (setq comint-completion-addsuffix t)
  ;(setq comint-process-echoes t) ;; reported that this is no longer needed
  (setq comint-eol-on-send t)
  (setq w32-quote-process-args ?\")

  (setq shell-mode-hook 'my-shell-setup)

  ;; Prevent issues with the Windows null device (NUL)
  ;; when using cygwin find with rgrep.
  (defadvice grep-compute-defaults (around grep-compute-defaults-advice-null-device)
    "Use cygwin's /dev/null as the null-device."
    (let ((null-device "/dev/null"))
  	ad-do-it))
  (ad-activate 'grep-compute-defaults)
#+END_SRC

Re: Comint and windows

[Filipp Gunbin]

On 05/11/2015 10:26 -0800, Jeffrey DeLeo wrote:

> I used to use emacs regularly on Windows, along with cygwin. I no longer
> do. I did use shell and other processes successfully, this is from my
> .emacs on Windows. I can't say what is relevant anymore, though.

It would be helpful to mention what Emacs you used - native or Cygwin
version.

I've used Cygwin Emacs for some years, there was no need for such setup
(except, maybe, for `w32-quote-process-args' - I don't know its meaning
and it's absent on Macos, where I am currently).

Filipp

Re: Comint and windows

[Jeffrey DeLeo]

Filipp Gunbin <fgunbin@fastmail.fm> writes:

> It would be helpful to mention what Emacs you used - native or Cygwin
> version.

Good point - I was using native Windows emacs.

Re: Comint and windows

[Sam Halliday]

Thanks Eli, that was exactly it! It was possible to tell the subprogram (a Java app that uses jline) to not buffer and everything started to work.

On Thursday, 5 November 2015 16:22:48 UTC, Eli Zaretskii  wrote:
> > Date: Thu, 5 Nov 2015 00:12:51 -0800 (PST)
> > From: Sam Halliday <sam.halliday@gmail.com>
> > 
> > I've been forced to use Windows at work and I'm finding some of my modes don't work.
> > 
> > One mode that is not working for me is sbt-mode:
> > 
> > https://github.com/hvesalai/sbt-mode/issues/33
> > 
> > It is a pretty standard implementation of a major mode that talks to an external process via comint. But it looks like commands typed in emacs are not being sent to the process.
> > 
> > Are there any known gotchas with writing these sorts of modes to run on windows?
> 
> Yes.  It's likely a buffering issue.  Windows doesn't have pty's, so
> communications with subprocesses is via pipes, which fail the isatty
> test, and so the subprocess most probably buffers its standard
> streams because it doesn't sense that they are connected to a terminal
> device.
> 
> Try invoking the subprocess in a way that disables buffering of
> stdin/stdout on the subprocess's side.  It could be some command-line
> switch or maybe some command you need to invoke immediately after
> invoking the subprocess.  (If there's no such option, ask the
> developers to provide one, or hack the code yourself.)