Refactoring code in .net - Các kĩ thuật Refactoring code trong .NET. Đây là một kỹ thuật không thể thiếu nếu các bạn muốn các dòng code của mình ngày một trong sáng, dễ hiểu hơn, clean hơn. Đặc biệt đây là một kỹ thuật không thể thiếu nếu bạn muốn áp dụng Agile/Extreme Programming với Unit Test. http://tungnt.net/meetup-ve-cac-ky-thuat-refactoring-code-trong-net/

1. Refactoring Code

2. About me
• Nguyen Thanh Tung
• Software architect at MISA JSC
• Microsoft Certified Professional Developer
• Technologies:
• Windows/Windows Phone
• ASP.NET
• XAML/Silverlight
• Windows Forms
• …
• Blog at: http://tungnt.net
• Facebook Page: https://www.facebook.com/tungnt185
• Meetup group: http://www.meetup.com/Ha-Noi-NET-Meetup/

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Table of contents
• Refactoring General
– What is refactoring?
– Who will refactor code?
– Why we need refactor code?
– When to refactor code?
– Where to refactor code?
• How to refactor code?

4. Refactoring General

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What is refactoring?
Refactoring means "to improve the design and
quality of existing source code without changing
its external behavior".
Martin Fowler
Bad Code Good CodeRefactoring

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Who will refactor code?
• You - Developers

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Why we need refactor code?
• Code constantly changes and its quality
constantly degrades (unless refactored)
• Requirements often change and code needs
to be changed to follow them

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When to refactor code?
• Bad smells in the code indicate need of refactoring
• Refactor when you
– Add a new method or class
– Fix an existing bug
– Reviewing someone else’s code
– Implement TDD (Test-Driven-Development)
• Unit tests guarantee that refactoring does not change the
behavior
– If there are no unit tests, write them

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Where to refactor code?
• Code smells - certain code structures have possibility of refactoring
• Types of code smells:
• Duplicated code
• Long method
• Large class
• Long parameter list
• Switch statements
• Improper naming
• Data members are public
• …

10. How to Refactor code?

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Naming
• Should be proper, descriptive and consistent
for readability and maintainability

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Duplicated code
• Violates the DRY (Don’t repeat yourself) principle
• Result of copy-pasted code
• Solutions: Extract method, extract class, pull-up method for
maintainability

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Long Method
Extract method to small methods are always better
(easy naming, understanding, less duplicate code)

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Conditional complexity
• Extract method

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Loosely Couple Code
• Extract Interface, Extract factory for
extensibility

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Return value instead of
exception
• Increase performance and readability

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Switch statement
• Can be replaced with polymorphism for
extensibility

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Remove multiple if
• Return ASAP (as soon as possible) For
readability

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Parameter object
• For readability and extensibility

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References

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References
• “Refactoring: Improving the Quality of
Existing Code“ by Telerik Academy
• 31 days of refactoring - lostechies.com

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Q&A