Info Catalog emacs-mime: rfc2047 emacs-mime: Basic Functions emacs-mime: qp

emacs-mime: time-date

 
 4.5 time-date
 =============
 
 While not really a part of the MIME library, it is convenient to
 document this library here.  It deals with parsing ‘Date’ headers and
 manipulating time.  (Not by using tesseracts, though, I’m sorry to say.)
 
    These functions convert between five formats: A date string, an Emacs
 time structure, a decoded time list, a second number, and a day number.
 
    Here’s a bunch of time/date/second/day examples:
 
      (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
      ⇒ (54 21 12 12 9 1998 6 nil 7200)
 
      (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
      ⇒ (13818 19266)
 
      (float-time '(13818 19266))
      ⇒ 905595714.0
 
      (seconds-to-time 905595714.0)
      ⇒ (13818 19266 0 0)
 
      (time-to-days '(13818 19266))
      ⇒ 729644
 
      (days-to-time 729644)
      ⇒ (961933 512)
 
      (time-since '(13818 19266))
      ⇒ (6797 9607 984839 247000)
 
      (time-less-p '(13818 19266) '(13818 19145))
      ⇒ nil
 
      (time-subtract '(13818 19266) '(13818 19145))
      ⇒ (0 121)
 
      (days-between "Sat Sep 12 12:21:54 1998 +0200"
                    "Sat Sep 07 12:21:54 1998 +0200")
      ⇒ 5
 
      (date-leap-year-p 2000)
      ⇒ t
 
      (time-to-day-in-year '(13818 19266))
      ⇒ 255
 
      (time-to-number-of-days
       (time-since
        (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
      ⇒ 4314.095589286675
 
    And finally, we have ‘safe-date-to-time’, which does the same as
 ‘date-to-time’, but returns a zero time if the date is syntactically
 malformed.
 
    The five data representations used are the following:
 
 DATE
      An RFC822 (or similar) date string.  For instance: ‘"Sat Sep 12
      12:21:54 1998 +0200"’.
 
 TIME
      An internal Emacs time.  For instance: ‘(13818 26466 0 0)’.
 
 SECONDS
      A floating point representation of the internal Emacs time.  For
      instance: ‘905595714.0’.
 
 DAYS
      An integer number representing the number of days since 00000101.
      For instance: ‘729644’.
 
 DECODED TIME
      A list of decoded time.  For instance: ‘(54 21 12 12 9 1998 6 t
      7200)’.
 
    All the examples above represent the same moment.
 
    These are the functions available:
 
 ‘date-to-time’
      Take a date and return a time.
 
 ‘float-time’
      Take a time and return seconds.  (This is a built-in function.)
 
 ‘seconds-to-time’
      Take seconds and return a time.
 
 ‘time-to-days’
      Take a time and return days.
 
 ‘days-to-time’
      Take days and return a time.
 
 ‘date-to-day’
      Take a date and return days.
 
 ‘time-to-number-of-days’
      Take a time and return the number of days that represents.
 
 ‘safe-date-to-time’
      Take a date and return a time.  If the date is not syntactically
      valid, return a “zero” time.
 
 ‘time-less-p’
      Take two times and say whether the first time is less (i.e.,
      earlier) than the second time.  (This is a built-in function.)
 
 ‘time-since’
      Take a time and return a time saying how long it was since that
      time.
 
 ‘time-subtract’
      Take two times and subtract the second from the first.  I.e.,
      return the time between the two times.  (This is a built-in
      function.)
 
 ‘days-between’
      Take two days and return the number of days between those two days.
 
 ‘date-leap-year-p’
      Take a year number and say whether it’s a leap year.
 
 ‘time-to-day-in-year’
      Take a time and return the day number within the year that the time
      is in.
 

Info Catalog emacs-mime: rfc2047 emacs-mime: Basic Functions emacs-mime: qp