+2007-04-12 Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
+
+ * Basic class extensions: Module#define_structure() method. Syntax:
+ define_structure :SomeName, :attr_a, :attr_b
+ is equivalent to
+ SomeName = Struct.new("SomeName", :attr_a, :attr_b)
+ except that the new Struct is not created if it already exists and the
+ attributes list is the same.
+