A verification of class structure evolution model and its parameters

It is widely accepted that the role of software "architect" that provide frameworks to program developers is important in the object-oriented software development processes. When developers try to extend the base classes given by the architect, they may want some guidelines that tell them how many subclasses and how many methods in one subclass are reasonable. So far we are not aware of such guidelines. Through measurements of Java and Delphi class libraries, we have distilled formulae that forecast the number of methods and the number of subclasses when constructing class trees from the base classes. We propose that we should focus to extract methods and attributes rather than class structure. The formulae we have formulated support this proposition.