Async shell-command-to-string?

Async shell-command-to-string?

[Johan Lindström]

Hi all!

I'd like to run something similar to shell-command-to-string, but 
that runs "asynchronously" in a "subprocess" in the "background". 
I've searched for all those things without finding anything suitable.

async-shell-command-to-string or whatever it would be called would 
take a callback for the string output when the subprocess is done.

Is there anything like that already?

If not, any hints on how to implement it? The async part of 
shell-command looks promising to nick.


/J

Re: Async shell-command-to-string?

[Lennart Borgman (gmail)]

Johan Lindström wrote:
> Hi all!
> 
> I'd like to run something similar to shell-command-to-string, but that 
> runs "asynchronously" in a "subprocess" in the "background". I've 
> searched for all those things without finding anything suitable.
> 
> async-shell-command-to-string or whatever it would be called would take 
> a callback for the string output when the subprocess is done.
> 
> Is there anything like that already?
> 
> If not, any hints on how to implement it? The async part of 
> shell-command looks promising to nick.


Look in the Emacs manual:

   (info "(elisp) Processes")

Re: Async shell-command-to-string?

[Johan Lindström]

At 23:53 2008-06-01, Johan Lindström wrote:
>Hi all!
>
>I'd like to run something similar to shell-command-to-string, but 
>that runs "asynchronously" in a "subprocess" in the "background". 
>I've searched for all those things without finding anything suitable.
>
>async-shell-command-to-string or whatever it would be called would 
>take a callback for the string output when the subprocess is done.

This is the result of a couple of hours of (rather fun) hacking.

I haven't plugged it into the app yet so I haven't seen it work in 
real life, but manual tests look good (including concurrent calls).


(require 'cl)

(defun async-shell-command-to-string (command callback)
   "Execute shell command COMMAND asynchronously in the
   background.

Return the temporary output buffer which command is writing to
during execution.

When the command is finished, call CALLBACK with the resulting
output as a string."
   (lexical-let
       ((output-buffer (generate-new-buffer " *temp*"))
        (callback-fun callback))
     (set-process-sentinel
      (start-process "Shell" output-buffer shell-file-name 
shell-command-switch command)
      (lambda (process signal)
        (when (memq (process-status process) '(exit signal))
          (with-current-buffer output-buffer
            (let ((output-string
                   (buffer-substring-no-properties
                    (point-min)
                    (point-max))))
              (funcall callback-fun output-string)))
          (kill-buffer output-buffer))))
     output-buffer))

(provide 'async-shell-command-to-string)


Code review anyone? I'm an elisp newbie so I'm certain there are 
things to improve. Rip it apart.


/J