Re: async 1.0

[John Wiegley <johnw@newartisans.com>]

>>>>> Richard Stallman <rms@gnu.org> writes:

> I didn't realize it could be so fast.  On my machine, emacs -Q -batch --eval
> "(+ 10 20)" takes about 1/4 second.

What kind of hardware are you using?  The Emacs that I'm running in off an SSD
with a lot of cache RAM available.  If I do it on my laptop, which also has an
SSD, I get the same times: 0.03713s.

I've also found another use for async.el: sandboxing.  The following allows me
execute a lambda synchronously, but without affecting the host Emacs
environment:

    (async-get (async-start FUNC))

I see this idiom being useful enough that I've reduced it to one function,
(async-sandbox FUNC).

Here's an example of using sandboxing to byte-compile a file, without letting
`eval-when-compile' forms affect the host environment:

    (let ((proc
           (async-start
            `(lambda ()
               (require 'bytecomp)
               ,(async-inject-variables "\\`load-path\\'")
               (let ((default-directory ,(file-name-directory file)))
                 (add-to-list 'load-path default-directory)
                 (ignore-errors
                   (load ,file))
                 ;; returns nil if there were any errors
                 (prog1
                     (byte-compile-file ,file)
                   (load ,file)))))))

      (unless (condition-case err
                  (async-get proc)
                (error
                 (ignore (message "Error: %s" err))))
        (ignore (message "Recompiling %s...FAILED" file))))

John