Leap Year

• 29

  FEB
  2008

  A Bug, Today Only

  I had to debug some tests that just started failing first thing this morning. I guess I should have procrastinated though, because they would have magically fixed themselves tomorrow morning. The cause of the one day only bug: Leap Year Day, of course.

  If you run the following code on a day like today, February 29th 2008, Date will choke on your invalid date:

  require "date"  
  
  class Date
    # Returns a Date in the past +year_offset+ years ago.
    def self.years_ago(year_offset)
      now = today
      Date.civil(now.year - year_offset, now.month, now.day)
    end
  end
  
  puts Date.years_ago(1)
  

  I came up with the following fix, which is accurate enough for my purposes:

  require "date"
  
  class Date   # Returns a Date in the past +year_offset+ years ago.
    def self.years_ago(year_offset)
      today - 365 * year_offset
    end
  end
  
  puts Date.years_ago(1)
  

  I'm not 100% sure that covers all cases though, so use with caution. Date's are tricky business!

  In: The Standard Library | Tags: Bugs, Date/Time & Leap Year | 1 Comment