Empirical Observations ofClass - level Encapsulation and InheritanceTim Menzies

OO design theory promises numerous beneets from the use of inheritance and the information hiding properties of encapsulated classes. Such promises are commonly used to justify the switch to the OO paradigm from (e.g.) functional decomposition languages like C. In this paper, we audit these claims via an analysis of 2000 Smalltalk classes in 5 applications. We will nd that, on average, applications use low levels of inheritance and information hiding at the class and class hierarchy level.