Improved Visitor Pattern Base on Normal Form

Design patterns are widely used in object-oriented programming and software engineering to enhance the software reuse and decrease class Coupling. And Visitor pattern is the import pattern in GoF's design patterns, which is a way of separating an algorithm from an object structure upon which it operates. But original visitor pattern violates interface segregation principle and dependency inversion principle. So when concrete visitable class change, there are large quantity of objects need to recompile. Some improved visitor patterns were put forward, but they had matter at running efficient or commonality. So normal form theory is used in this paper to analyze original visitor pattern, further more design an improved visitor pattern to solve problems which were mentioned former.