singleton       :  singleton example
random          :  example to automatically replace built-in C random
                   generator with ROOT random generator by simply loading
                   an additional library
factory         :  object factory example
prototype       :  prototype example, allowing areation of new prototypes
                   at runtime
proxy           :  proxy example
observer        :  observer examples, including modified version with
                   lazy evaluation
visitor         :  visitor example, with operations on geometrical shapes
iterator        :  iterator examples with linked list and recursive tree
virtualTemplate :  application of "double dispatch" to mimic
                   template virtual functions
