Research On Optimization Of Design Pattern Combination Operation

As a summary of software design experience,appropriate use of design pattern can effectively improve the reusability of software system and the efficiency of software maintenance.In practical applications,due to the complexity of software requirements,designers rarely use a single design pattern,but combine multiple design patterns according to specific application scenarios and previous design experience.However,in the absence of theoretical support and rigorous derivation,the effectiveness of the combination results cannot be guaranteed,which may adversely affect the quality of software products.Therefore,it is very essential to use formal methods to express the pattern combination accurately and determine whether the pattern combination is effective or not.By comparing the existing formal methods of pattern combination,the operator method can effectively show the results of pattern combination,but this method still has the disadvantage that the restriction operator semantic overlaps with the flattening and lifting operators.In view of the problems existing in the above operator method,the work of this thesis is as follows:(1)Based on abstract logic specification of pattern and Z notation,the operator method is optimized.On the basis of existing operators,newly constraint,superposition,extension and generalization operators are proposed.(2)The algebraic rules satisfied by the optimized operators are discussed,and the algebraic reasoning is used to verify that the optimized restriction,superposition,extension and generalization operators can effectively replace the previous restriction,superposition,flattening,generalization,extension and lifting operators.By reducing the number of operators,the semantic overlap between multiple patterns is reduced.(3)By analysing preserved attributes of optimal operators,a method for judgingthe validity of pattern combination is summarized,and the correctness of the method is verified by a practical pattern-oriented case.Meanwhile,the comparison shows that the optimized operator method in this thesis is superior to the previous methods in eliminating overlap of operators.