date = Date.new(2011, 6, 9)
date.stamp("March 1, 1999")         #=> "June  9, 2011"
date.stamp("Jan 1, 1999")           #=> "Jun  9, 2011"
date.stamp("Jan 01")                #=> "Jun 09"
date.stamp("Sunday, May 1, 2000")   #=> "Thursday, June  9, 2011"
date.stamp("Sun Aug 5")             #=> "Thu Jun  9"
date.stamp("12/31/99")              #=> "06/09/11"
date.stamp("DOB: 12/31/2000")       #=> "DOB: 06/09/2011"

官網 https://github.com/jeremyw/stamp 出處 http://www.dwellable.com/blog/Rails-Rumble-Winners-Gem-Teardown