Code Refactoring using design patterns

by Yassine Al Harek

Supervised by Dr. hab. inż. Anna Fabijańska, Prof. PŁ

Introduction

This thesis focuses on software maintenance, and more precisely the state-of-art of automatic detection and refactoring solutions. This work intends to plant a seed of a robust solution automating the process of code smells detection and their transformation into a more readable and reusable code while profiting from the advantages of design patterns.

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State of art

Prechlet et al.(2001) put the popular idea of preferring design patterns to simpler Object-Oriented solutions to test.

Demeyer (2005) tested the effect of virtual function in C++ on program efficiency, and whether the idea that polymorphism improves maintainability on detriment

of performance, is a valid one.

Tsantalis and Chatzigeorgiou (2010) proposed an algorithm to extract refactoring suggestions to the Type-checking code smell and eventually propose an application of the refactoring.

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Problem statements

Principles of Object-Oriented Paradigm are frequently dismissed.
The process of refactoring is costly.
The Netbeans Platform has a lack of refactoring tools.
The existing solutions do not propose automatic refactoring.
The existing solutions do not profit from the advantages of design patterns.

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Proposed solution

A Netbeans plugin that detect code smells and suggests an automatic refactoring. As a commencement, the Type-checking code smell was covered. The tool detect the smell based on the criteria established by Tsantalis et Chatzigeorgiou. Then, a refactoring to a Strategy Pattern is conducted.

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The code smell AST

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sample

launching the detection

C hange made to the class containing the code smell

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sample(2)

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Future Work

Cover remaining code smells
Improve the detection efficiency, i.e. reducing "false positives".
Provide a visualisation (UML diagrams, among others) of changes made.
Create a database of accepted refactoring by users

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Conclusion

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