Introduction to Refactoring

Transcript

1. Refactoring The only way to go fast is to go well (by small steps)
2. Introduction https://www.thoughtworks.com/
3. What makes this a great book? • Refactoring Vocabulary • Refactors • Code Smells • Approach (refactor, test, commit) • For each type of refactor • Why • Example • Steps to refactor
4. What is refactoring? • Refactoring is the process of changing a software system in a way that does not alter the external behavior of the code yet improves its internal structure • Changes in small steps • Change code • Run tests • Commit
5. First Example • First step in refactoring: solid set of tests • Test Feedback • Separate different parts • Switch to Visual Studio and refactor this code base: • https://github.com/michelschep/refactoring-first-example
6. Why refactor? • Improves the design of software • Makes software easier to understand • Helps find bugs • Helps program faster
7. When refactor? • Preparatory refactoring: make it easier to add a feature • Comprehension refactoring: make it easier to understand • Litter-pickup refactoring (boy scout rule) • Refactoring in a code review (pair programming)
8. What do I tell my manager? • Don’t tell! • Software developers are professionals • Our job is to build effective software as rapidly as we can • Refactoring is a big aid into building software quickly • I’m being paid for my expertise in programming new capabilities fast, and the fastest way is by refactoring – therefore I refactor
10. When it is not refactoring… “If someone says their code was broken for several days while they are refactoring, you can be pretty sure the were not refactoring” – Martin Fowler
11. Two hats
12. Refactoring Vocabulary • Extract Function • Inline Variable • Change Function Declaration • Split Loop • Slide Statements • Replace Temp with Query
13. Refactor process • (Write test) • Refactor • Run Test • Commit • etc
14. Oh and what about performance? • It is much easier to improve the performance of a well-refactored code base • Example: Replace Temp with Query (178)
16. Let’s refactor this!
17. Now really show me the code!
18. Result
19. Summary • Prepare refactoring (write test if not available) • Apply refactor step • Test • Commit
20. Links • https://github.com/michelschep/refactoring-first-example • https://refactoring.com/catalog/ • https://refactoring.guru