ActiveSupport、Date.yesterday
>> require "rubygems" => true >> require "active_support" => true >> Date.current => Wed, 04 Feb 2009 >> Date.yesterday => Tue, 03 Feb 2009
>> require "rubygems" => true >> require "active_support" => true >> Date.current => Wed, 04 Feb 2009 >> Date.yesterday => Tue, 03 Feb 2009