1 files changed, 37 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/duplicable.rb b/activesupport/lib/active_support/core_ext/duplicable.rb
new file mode 100644
index 0000000000..adbbfd8c60
--- /dev/null
+++ b/activesupport/lib/active_support/core_ext/duplicable.rb
@@ -0,0 +1,37 @@
+class Object
+  # Can you safely .dup this object?
+  # False for nil, false, true, symbols, and numbers; true otherwise.
+  def duplicable?
+    true
+  end
+end
+
+class NilClass #:nodoc:
+  def duplicable?
+    false
+  end
+end
+
+class FalseClass #:nodoc:
+  def duplicable?
+    false
+  end
+end
+
+class TrueClass #:nodoc:
+  def duplicable?
+    false
+  end
+end
+
+class Symbol #:nodoc:
+  def duplicable?
+    false
+  end
+end
+
+class Numeric #:nodoc:
+  def duplicable?
+    false
+  end
+end