code.delx.au - gnu-emacs-elpa/blob - README.md

   1 # emacs-async
   2
   3 async.el is an exceedingly simple module for doing asynchronous processing in
   4 Emacs, by spawning a child Emacs interpreter to execute a lambda function, and
   5 calling back when the job is done.
   6
   7 It uses a very simple syntax:
   8
   9     (async-start
  10        ;; What to do in the child process
  11        (lambda ()
  12          (message "This is a test")
  13          (sleep-for 3)
  14          222)
  15
  16        ;; What to do when it finishes
  17        (lambda (result)
  18          (message "Async process done, result should be 222: %s" result)))
  19
  20 If you omit the callback function, `async-start` returns a process object that
  21 you can call `async-get` on when you're ready to wait for the result value:
  22
  23     (let ((proc (async-start
  24                    ;; What to do in the child process
  25                    (lambda ()
  26                      (message "This is a test")
  27                      (sleep-for 3)
  28                      222))))
  29
  30         (message "I'm going to do some work here") ;; ....
  31
  32         (message "Waiting on async process, result should be 222: %s"
  33                  (async-get proc)))
  34
  35 If you don't want to use a callback, and you don't care about any return value
  36 form the child process, pass the `ignore` symbol as the second argument (if
  37 you don't, and never call `async-get', it will leave *emacs* process buffers
  38 hanging around):
  39
  40     (async-start
  41      (lambda ()
  42        (delete-file "a remote file on a slow link" nil))
  43      'ignore)