1 files changed, 44 insertions, 0 deletions
diff --git a/lib/delegate.rb b/lib/delegate.rb
new file mode 100644
index 0000000000..e5943cead8
--- /dev/null
+++ b/lib/delegate.rb
@@ -0,0 +1,44 @@
+#  Delegation class that delegates even methods defined in super class,
+# which can not be covered with normal method_missing hack.
+#  
+#  Delegater is the abstract delegation class. Need to redefine
+# `__getobj__' method in the subclass.  SimpleDelegater is the 
+# concrete subclass for simple delegation.
+#
+# Usage:
+#   foo = Object.new
+#   foo = SimpleDelegater.new(foo)
+#   foo.type # => Object
+
+class Delegater
+
+  def initialize(obj)
+    preserved = ["id", "equal?", "__getobj__"]
+    for t in self.type.ancestors
+      preserved |= t.instance_methods
+      break if t == Delegater
+    end
+    for method in obj.methods
+      next if preserved.include? method
+      eval "def self.#{method}(*args); __getobj__.send :#{method}, *args; end"
+    end
+  end
+
+  def __getobj__
+    raise NotImplementError, "need to define `__getobj__'"
+  end
+
+end
+
+class SimpleDelegater<Delegater
+
+  def initialize(obj)
+    super
+    @obj = obj
+  end
+
+  def __getobj__
+    @obj
+  end
+
+end