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

   1 <p><a href="http://www.gnu.org/licenses/gpl-3.0.txt"><img src="https://img.shields.io/badge/license-GPL_3-green.svg" alt="License GPL 3" /></a>
   2 <a href="http://melpa.org/#/async"><img src="http://melpa.org/packages/async-badge.svg" alt="MELPA" title="" /></a>
   3 <a href="http://stable.melpa.org/#/async"><img src="http://stable.melpa.org/packages/async-badge.svg" alt="MELPA Stable" title="" /></a></p>
   4
   5
   6 # emacs-async
   7
   8 `async.el` is a module for doing asynchronous processing in Emacs.
   9
  10 # Install
  11
  12 ## Install dired-async
  13
  14 Add to your `.emacs.el`:
  15
  16     (autoload 'dired-async-mode "dired-async.el" nil t)
  17     (dired-async-mode 1)
  18
  19 This will allow you to run  asynchronously
  20 the dired commands for copying, renaming and symlinking.
  21 If you are a [helm](https://github.com/emacs-helm/helm) user, this will allow you
  22 to copy, rename etc... asynchronously from [helm](https://github.com/emacs-helm/helm).
  23 Note that with [helm](https://github.com/emacs-helm/helm)
  24 you can disable this by running the copy, rename etc... commands with a prefix argument.
  25
  26 If you don't want to make dired/helm asynchronous disable it with `dired-async-mode`.
  27
  28 ## Enable asynchronous compilation of your (M)elpa packages
  29
  30 By default emacs package.el compile packages in its running emacs session.
  31 This is not a problem when installing a new package (which is not actually loaded in current emacs)
  32 but it may create errors and bad compilation when upgrading a package (old version of package is already loaded
  33 and running in current emacs).
  34 You can remedy to this by allowing async to compile your packages asynchronously,
  35 (helm and magit actually do this by default,
  36 so if you are using these packages they will compile asynchronously)
  37 to do this, add to your init file:
  38
  39     (async-bytecomp-package-mode 1)
  40
  41
  42 You can control which packages will compile async with `async-bytecomp-allowed-packages`.
  43 Set it to `'(all)` to be sure you will compile all packages asynchronously.
  44
  45 # Usage
  46
  47 The interface is intended to be very easy to use:
  48
  49 ## async-start
  50
  51     async-start START-FUNC FINISH-FUNC
  52
  53 Execute START-FUNC (often a lambda) in a subordinate Emacs process.  When
  54 done, the return value is passed to FINISH-FUNC.  Example:
  55
  56     (async-start
  57        ;; What to do in the child process
  58        (lambda ()
  59          (message "This is a test")
  60          (sleep-for 3)
  61          222)
  62
  63        ;; What to do when it finishes
  64        (lambda (result)
  65          (message "Async process done, result should be 222: %s" result)))
  66
  67 If FINISH-FUNC is `nil` or missing, a future is returned that can be inspected
  68 using `async-get`, blocking until the value is ready.  Example:
  69
  70     (let ((proc (async-start
  71                    ;; What to do in the child process
  72                    (lambda ()
  73                      (message "This is a test")
  74                      (sleep-for 3)
  75                      222))))
  76
  77         (message "I'm going to do some work here") ;; ....
  78
  79         (message "Waiting on async process, result should be 222: %s"
  80                  (async-get proc)))
  81
  82 If you don't want to use a callback, and you don't care about any return value
  83 from the child process, pass the `'ignore` symbol as the second argument (if
  84 you don't, and never call `async-get`, it will leave ``*emacs*`` process buffers
  85 hanging around):
  86
  87     (async-start
  88      (lambda ()
  89        (delete-file "a remote file on a slow link" nil))
  90      'ignore)
  91
  92 Note: Even when FINISH-FUNC is present, a future is still returned except that
  93 it yields no value (since the value is passed to FINISH-FUNC).  Calling
  94 `async-get` on such a future always returns `nil`.  It can still be useful,
  95 however, as an argument to `async-ready` or `async-wait`.
  96
  97 ## async-start-process
  98
  99     async-start-process NAME PROGRAM FINISH-FUNC &rest PROGRAM-ARGS
 100
 101 Start the executable PROGRAM asynchronously.  See `async-start`.  PROGRAM is
 102 passed PROGRAM-ARGS, calling FINISH-FUNC with the process object when done.
 103 If FINISH-FUNC is `nil`, the future object will return the process object when
 104 the program is finished.  Set DEFAULT-DIRECTORY to change PROGRAM's current
 105 working directory.
 106
 107 ## async-get
 108
 109     async-get FUTURE
 110
 111 Get the value from an asynchronously called function when it is ready.  FUTURE is
 112 returned by `async-start` or `async-start-process` when its FINISH-FUNC is
 113 `nil`.
 114
 115 ## async-ready
 116
 117     async-ready FUTURE
 118
 119 Query a FUTURE to see if its function's value is ready -- i.e., if no blocking
 120 would result from a call to `async-get` on that FUTURE.
 121
 122 ## async-wait
 123
 124     async-wait FUTURE
 125
 126 Wait for FUTURE to become ready.
 127
 128 ## async-inject-variables
 129
 130     async-inject-variables INCLUDE-REGEXP &optional PREDICATE EXCLUDE-REGEXP
 131
 132 Return a `setq` form that replicates part of the calling environment.  It sets
 133 the value for every variable matching INCLUDE-REGEXP and also PREDICATE.  It
 134 will not perform injection for any variable matching EXCLUDE-REGEXP (if
 135 present).  It is intended to be used as follows:
 136
 137     (async-start
 138        `(lambda ()
 139           (require 'smtpmail)
 140           (with-temp-buffer
 141             (insert ,(buffer-substring-no-properties (point-min) (point-max)))
 142             ;; Pass in the variable environment for smtpmail
 143             ,(async-inject-variables "\\`\\(smtpmail\\|\\(user-\\)?mail\\)-")
 144             (smtpmail-send-it)))
 145        'ignore)