module ActiveSupport #:nodoc:
  module CoreExtensions #:nodoc:
    module Date #:nodoc:
      module Behavior
        # Enable more predictable duck-typing on Date-like classes. See
        # Object#acts_like?.
        def acts_like_date?
          true
        end

        # Date memoizes some instance methods using metaprogramming to wrap
        # the methods with one that caches the result in an instance variable.
        # If a Date is frozen but the memoized method hasn't been called, the
        # first call will result in a frozen object error since the memo
        # instance variable is uninitialized. Work around by eagerly memoizing
        # before freezing.
        def freeze #:nodoc:
          self.class.private_instance_methods(false).each do |m|
            if m.to_s =~ /\A__\d+__\Z/
              instance_variable_set(:"@#{m}", [send(m)])
            end
          end

          super
        end
      end
    end
  end
end