1 files changed, 31 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/date/freeze.rb b/activesupport/lib/active_support/core_ext/date/freeze.rb
new file mode 100644
index 0000000000..4edd715ba2
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/date/freeze.rb
@@ -0,0 +1,31 @@
+# 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.
+#
+# Ruby 1.9 uses a preinitialized instance variable so it's unaffected.
+# This hack is as close as we can get to feature detection:
+if RUBY_VERSION < '1.9'
+  require 'date'
+  begin
+    ::Date.today.freeze.jd
+  rescue => frozen_object_error
+    if frozen_object_error.message =~ /frozen/
+      class Date #:nodoc:
+        def freeze
+          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