Working Effectively with Legacy Code

Description

MICHAEL C. FEATHERS works for Object Mentor, Inc., one of the world’s top providers of mentoring, skill development, knowledge transfer, and leadership services in software development. He currently provides worldwide training and mentoring in Test-Driven Development (TDD), Refactoring, OO Design, Java, C#, C++, and Extreme Programming (XP). Michael is the original author of CppUnit, a C++ port of the JUnit testing framework, and FitCpp, a C++ port of the FIT integrated-testing framework. A member of ACM and IEEE, he has chaired CodeFest at three OOPSLA conferences.

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Proven strategies for maintaining and optimizing legacycode to get the most out of your existing applications.

• Examples in C-sharp, C++, and Java, as well as strategies for better using theindustry standard modeling language: UML 2.0
• Addresses the very concrete problems that programmers face working in the contextof large untested code bases
• Based on successful classes for Object Mentor, the author helps organizationsmaintain older systems rather than go to the cost of developing new ones

This book provides programmers with the ability to cost effectively handlecommon legacy code problems without having to go through the hugelyexpensive task of rewriting all existing code. It describes a series of practicalstrategies that developers can employ to bring their existing softwareapplications under control. The author provides useful guidance about how touse these strategies when refactoring or making functional changes to codebases. One of the book’s key points is that it teaches developers to write teststhat can be used to make sure they are not unintentionally changing theapplication as they optimize it. Examples are provided in Java, C++, and Csharp,and the book assumes that the reader has some knowledge of UMLnotation. Strategies using UML and code in C++ and Java primarily whilelanguage independent advice will be delivered in side bars and appendices forlanguage specific users.

• I. THE MECHANICS OF CHANGE.
• 1. Changing Software.
• 2. Working with Feedback.
• 3. Sensing and Separation.
• 4. The Seam Model.
• 5. Tools.
• II. CHANGING SOFTWARE.
• 6. I Don’t Have Much Time and I Have To Change It.
• 7. It Takes Forever To Make a Change.
• 8. How Do I Add a Feature?
• 9. I Can’t Get This Class into a Test Harness.
• 10. I Can’t Run This Method into a Test Harness.
• 11. I Need to Make a Change. What Methods Should I Test?
• 12. I Need to Make Many Changes In One Area Do I Have To Break.
• 13. I Need To Make a Change but I Don’t Know What Tests To Write.
• 14. Dependencies on Libraries Are Killing Me.
• 15. My Application Is All API Calls.
• 16. I Don’t Understand the Code Well Enough To Change It.
• 17. My Application Has No Structure.
• 18. My Test Code Is in the Way.
• 19. My Project Is Not Object-Oriented. How Do I Make Safe Changes?
• 20. This Class Is Too Big and I Don’t Want It to Get Any Bigger.
• 21. I’m Changing The Same Code All Over the Place.
• 22. I Need To Change a Monster Method and I Can’t Write Tests for It.
• 23. How Do I Know That I’m Not Breaking Anything?
• 24. We Feel Overwhelmed. It Isn’t Going To Get Any Better.
• III. DEPENDENCY BREAKING TECHNIQUES.
• 25. Dependency Breaking Techniques.
• Appendix: Refactoring.
• Glossary.

Get more out of your legacy systems: more performance, functionality, reliability, and manageability

Is your code easy to change? Can you get nearly instantaneous feedback when you do change it? Do you understand it? If the answer to any of these questions is no, you have legacy code, and it is draining time and money away from your development efforts.

In this book, Michael Feathers offers start-to-finish strategies for working more effectively with large, untested legacy code bases. This book draws on material Michael created for his renowned Object Mentor seminars: techniques Michael has used in mentoring to help hundreds of developers, technical managers, and testers bring their legacy systems under control.

The topics covered include

• Understanding the mechanics of software change: adding features, fixing bugs, improving design, optimizing performance
• Getting legacy code into a test harness
• Writing tests that protect you against introducing new problems
• Techniques that can be used with any language or platform—with examples in Java, C++, C, and C#
• Accurately identifying where code changes need to be made
• Coping with legacy systems that aren’t object-oriented
• Handling applications that don’t seem to have any structure

This book also includes a catalog of twenty-four dependency-breaking techniques that help you work with program elements in isolation and make safer changes.

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