Amanda Sopkin - The Refactoring Balance Beam: When to Make Changes and When to Leave it Alone

Many developers struggle to find the balance between striving to improve existing code and letting good enough alone by accepting certain shortcomings. As a new developer to a team it can be difficult to understand existing strategies and patterns that are sometimes flat out bad (and often openly acknowledged as such). Often the result of tight deadlines or unclear specifications, even the best developers write code they later look back upon with shudders. So how do we decide when refactoring is worth it? Come learn strategies for refactoring with minimal impact, methods for working with bad code you can’t change, and strategies for knowing the difference between what is fixable and what is better left alone.

https://us.pycon.org/2019/schedule/presentation/213/

Transcript

6. Why refactor?
7. Why refactor?
17. Common Code Smell #1 It’s too long!
18. • • • ◦ ◦
20. • •
21. • •
23. Code Smells: Long methods • • • ◦ ◦ ◦ ◦
24. Tool: Replace Method with Method Object
25. Tool: Replace Method with Method Object
26. Tool: Introduce a parameter object
27. • • • ◦
28. Common Code Smell #2: It’s not useful enough!
29. • • • ◦ ◦ ◦
32. • • • ◦ ◦
33. Common Code Smell #3: OOP issues
34. Code smell: Divergent change • • • ◦ ◦
35. Code smell: Shotgun surgery • • • ◦ ◦
36. Code smell: shotgun surgery
37. Tool: Move Class
38. Code smell: Parallel inheritance hierarchies • ◦ • • ◦ ◦
39. Code Smell: Parallel inheritance hierarchies
40. Tool: Move Class
41. • • • ◦ ◦
42. • • • ◦ ◦
43. Tool: Extract Class
44. Tool: Extract Class
45. • • •
46. Tool: Replace Type Code with State
47. • • • ◦ ◦
48. Tool: Hide Delegate
49. Tool: Hide Delegate
50. • • • ◦
51. • • • ◦
52. Do I need to inherit this class?
54. Lets talk Pythonic Code Smells!
55. • • • ◦ ◦ ◦
56. • • • ◦ ◦
57. Codesmell: Unnecessary boilerplate code
58. Dataclasses and attrs
59. Dataclasses and attrs
60. • • • ◦
61. • • • ◦
84. • ◦ • ◦
85. • • ◦ ◦ ◦
86. • •
87. • •
88. • •
91. • (Expand) (Contract) (Transition)
92. • •
107. THANK YOU! @amandasopkin
108. Sources Flat Icon: https://www.flaticon.com/ Refactoring Python by Brett Slatkin: https://www.youtube.com/watch?v=D_6ybDcU5gc Real Python: https://realpython.com/python-refactoring/ Pep 20: https://www.python.org/dev/peps/pep-0020/ Beyond Pep 8 by Raymond Hettinger: https://www.youtube.com/watch?v=wf-BqAjZb8M Refactoring by Martin Fowler: https://www.csie.ntu.edu.tw/~r95004/Refactoring_improving_the_design_of_existing_code.pdf