ActiveSupport、Date::DATE_FORMATS

everyday Ruby 
>> require "rubygems"
=> true
>> require "active_support"
=> true
>> Date::DATE_FORMATS
=> {:rfc822=>"%e %b %Y", :number=>"%Y%m%d", :short=>"%e %b", :long=>"%B %e, %Y", :db=>"%Y-%m-%d", :long_ordinal=>#<Proc:0xb79d5d5c@/usr/local/ruby-1.8.7/lib/ruby/gems/1.8/gems/activesupport-2.2.2/lib/active_support/core_ext/date/conversions.rb:11>}