Can Emacs run command in background

Question

I have an Emacs command like following:

(defun query-lisp (word)
  (interactive "sType a word to query:")
  (message "%s" (query word)))

The query operation is a time-consuming operation. When this command is running Emacs blocks the whole frame. Is there a way to make Emacs run this command in the background or block only a single window such as the minibuffer?

Answer 1

If you plan to use an external process (which you have indicated in a comment to another question), you can use the following:

 (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)

This will return a process object. You can either send the output to a buffer, or you could attach a filter function to the process. In the latter case, this is a function that is called every time your process emits any output.

In addition, you could attach a sentinel function to your process. This function is called everytime the status of your process changes, this is useful to find out when it has exited.

There are several examples of the above in the source code of Emacs, one such example is compile.el.