on::::示例.
C#.codice_1 类别本身在这里不做任合事。codice_2 变数则是一个存 codice_1 实例的 Dictionary 或 Map ，其透过codice_4来存取。
Smalltalk.The following is an example (in Smalltalk) of a typical accessor method to return the value of a variable using lazy initi