使用elisp创建repeated schedule time

我们都直到使用 (org-schedule ARG &optional TIME) 函数能够给任务分配一个规划的任务开始时间。 下面是关于 org-schedule 的函数说明

(org-schedule ARG &optional TIME)

Insert the SCHEDULED: string with a timestamp to schedule a TODO item.
With one universal prefix argument, remove any scheduling date from the item.
With two universal prefix arguments, prompt for a delay cookie.
With argument TIME, scheduled at the corresponding date.  TIME can
either be an Org date like "2011-07-24" or a delta like "+2d".

但是从它的doc-string中你应该看不出来它其实可以用来给任务分配一个 repeated schedule time.

一个 repeated schedule time 由两部分组成，一个是 规划的任务开始时间,一个是 重复的时间间隔. 比如 SCHEDULED: <2005-10-01 Sat +1m> 就表示 该任务规划的任务开始时间是 2005-10-01,同时它是一个月度重复任务。

但是若你试着使用 (org-schedule 4 "2005-10-01 +1m"),你会发现生成的规划时间并不带有 +1m 这个重复的部分。

* test
SCHEDULED: <2005-10-01 六>

通过查看 org-schedule 的代码你会发现它实际调用的 org--deadline-or-schedule 函数来生成规划日期，而 org--deadline-or-schedule 中有这么一段代码

;; Save repeater cookie from either TIME or current scheduled
;; time stamp.  We are going to insert it back at the end of
;; the process.
(repeater (or (and (org-string-nw-p time)
                   ;; We use `org-repeat-re' because we need
                   ;; to tell the difference between a real
                   ;; repeater and a time delta, e.g. "+2d".
                   (string-match org-repeat-re time)
                   (match-string 1 time))
              (and (org-string-nw-p old-date)
                   (string-match "\\([.+-]+[0-9]+[hdwmy]\
\\(?:[/ ][-+]?[0-9]+[hdwmy]\\)?\\)"
                                 old-date)
                   (match-string 1 old-date)))))

也就是说，要想保留 重复时间间隔 部分的信息，要求输入的 TIME 符合 org-repeate-re 的正则表达式。

而 org-repeate-re 的默认值为:

org-repeat-re is a variable defined in ‘org.el’.
Its value is
"[[<][0-9]\\{4\\}-[0-9][0-9]-[0-9][0-9] [^]>
]*?\\([.+]?\\+[0-9]+[hdwmy]\\(/[0-9]+[hdwmy]\\)?\\)"

  This variable may be risky if used as a file-local variable.

Documentation:
Regular expression for specifying repeated events.
After a match, group 1 contains the repeat expression.

也就是需要以 < 或 [ 开头. 因此,要让 org-schedule 生成repeated schedule time只需要将时间写入 <> 或 [] 中即可:

比如将上面语句改成 (org-schedule 4 "<2005-10-01 +1m>"), 就能看到结果

* test
  SCHEDULED: <2005-10-01 六 +1m>