emacs-async库简要说明

Table of Contents

• 1. async简介
• 2. API说明
  • 2.1. (async-start START-FUNC FINISH-FUNC)
  • 2.2. (async-get FUTURE)
  • 2.3. (async-start-process NAME PROGRAM FINISH-FUNC &rest PROGRAM-ARGS)
  • 2.4. (async-ready FUTURE)
  • 2.5. (async-wait FUTURE)
  • 2.6. (async-inject-variables INCLUDE-REGEXP &optional PREDICATE EXCLUDE-REGEXP)

async简介

async包提供了在Emacs中异步执行elisp代码的一种方式

API说明

(async-start START-FUNC FINISH-FUNC)

async-start会创建一个Emacs子进程,并由子进程执行START-FUNC. 子进程执行完START-FUNC后,START-FUNC的返回值会作为参数触发父进程Emacs中的FINISH-FUNC调用.

下面是个例子:

    (async-start           ;; What to do in the child process           (lambda ()             (message "This is a test")             (sleep-for 3)             222)           ;; What to do when it finishes           (lambda (result)             (message "Async process done, result should be 222: %s" result)))

这里FINISH-FUNC一般为带一个参数的函数,但也可以是nil或直接不填. 这种情况下可以在后期使用`async-get’函数获取`START-FUNC’的值. (在调用async-get函数前,会有一个*emacs*进程一直存在)

若对`START-FUNC’的返回值不感兴趣,则`FINISH-FUNC’的值可以为’ingore

async-start返回一个process对象,该process对象被称为 FUTURE

(async-get FUTURE)

若`async-start’中的FINISH-FUNC为nil或没填时,可以使用`async-get’函数来阻塞式地获取`START-FUNC’的返回值.

这里参数`FUTURE’为`async-start’或`async-start-process’的返回process对象.

下面是一个例子

    (let ((proc (async-start                       ;; What to do in the child process                       (lambda ()                         (message "This is a test")                         (sleep-for 3)                         222))))            (message "I'm going to do some work here") ;; ....            (message "Waiting on async process, result should be 222: %s"                     (async-get proc)))

(async-start-process NAME PROGRAM FINISH-FUNC &rest PROGRAM-ARGS)

使用`PROGRAM-ARGS’作为命令参数异步执行`PROGRAM’. 当`PROGRAM’执行完毕后,以该process对象为参数调用`FINISH-FUNC’.

`PROGRAM’执行时的当前工作目录被设置为变量`DEFAULT-DIRECTORY’的值.

若`FINISH-FUNC’为nil,则`async-start-process’一直等到`PROGRAM’执行完毕后才返回 FUTURE 对象

(async-ready FUTURE)

判断`FUTURE’是否执行完毕

(async-wait FUTURE)

等待FUTURE,直到其执行完毕

(async-inject-variables INCLUDE-REGEXP &optional PREDICATE EXCLUDE-REGEXP)

该函数会生成一个`setq’语句,该语句常用于为子Emacs进程置所有匹配`INCLUDE-REGEXP’和符合`PREDICATE’判定的变量为当前主Emacs中的值.

若设置了`EXCLUDE-REGEXP’,则标示了哪些变量即使符合INCLUDE-REGEXP或PREDICATE的条件,也要排除在外.

例如

    (async-start           `(lambda ()              (require 'smtpmail)              (with-temp-buffer                (insert ,(buffer-substring-no-properties (point-min) (point-max)))                ;; Pass in the variable environment for smtpmail                ,(async-inject-variables "\\`\\(smtpmail\\|\\(user-\\)?mail\\)-")                (smtpmail-send-it)))           'ignore)