.net code: some ideas to improve yours
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The document discusses ways to improve .NET code quality by writing cleaner, more readable and maintainable code. It provides examples of refactoring a method to filter and sort a collection of integers in increasingly cleaner ways using LINQ and extensions. The document emphasizes writing code that is easy for humans to understand and maintaining a sustainable development rhythm to avoid slowdowns from technical debt.
.net code: some ideas to improve yours
- 1. .net code some ideas to improve yours Carlos Lopes @carlosaml ThoughtWorks
- 2. code
- 4. so how can you write be@er code?
- 5. and so on
- 6. .net
- 7. C#
- 9. ok
- 10. IEnumerable<int> FilterAndSort(IEnumerable<int> numbers) { var evens = new List<int>(); foreach (var i in numbers) { if (i % 2 == 0) { evens.Add(i); } } evens.Sort(); return evens; }
- 11. IEnumerable<int> FilterAndSortRevisited(IEnumerable<int> numbers) { var evens = numbers.Where(i => i % 2 == 0).ToList(); evens.Sort(); return evens; }
- 12. IEnumerable<int> FilterAndSortStrikingBack(IEnumerable<int> numbers) { return numbers .Where(i => i % 2 == 0) .OrderBy(i => i); }
- 13. IEnumerable<int> FilterAndSortEvenBe@er(IEnumerable<int> numbers) { return from n in numbers where n % 2 == 0 orderby n select n; }
- 14. IEnumerable<int> FilterAndSortYetAgain(IEnumerable<int> numbers) { return from n in numbers where n.IsEven() orderby n select n; }
- 15. wait
- 16. IEnumerable<int> FilterAndSortYetAgain(IEnumerable<int> numbers) { return from n in numbers where n.IsEven() orderby n select n; }
- 17. public staWc class MyExtensions { public staWc bool IsEven(this int number) { return number % 2 == 0; } }
- 18. we’ll come back to this
- 19. IEnumerable<int> FilterAndSort(IEnumerable<int> numbers) { var evens = new List<int>(); foreach (var i in numbers) { if (i % 2 == 0) { evens.Add(i); } } evens.Sort(); return evens; }
- 20. IEnumerable<int> FilterAndSortYetAgain(IEnumerable<int> numbers) { return from n in numbers where n.IsEven() orderby n select n; }
- 21. so what?
- 22. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” Mar;n Fowler
- 24. Robert C. Mar;n
- 25. fast, slow, slower rhythm
- 27. release 1.0 is quickly delivered
- 28. release 2.0 is delivered
- 29. but the junky code slows you down
- 30. then you go slower and slower
- 31. mysterious bugs
- 32. demoWvaWon
- 33. etc
- 34. and around release 4.0 …
- 36. 5.0 !!!
- 38. less code
- 39. less bugs
- 40. “If you love wri;ng code -‐-‐ really, truly love to write code -‐-‐ you'll love it enough to write as liEle of it as possible.” Jeff Atwood
- 41. “Code is bad. It rots. It requires periodic maintenance. It has bugs that need to be found. New features mean old code has to be adapted.” Rich Skrenta
- 42. coming back
- 44. “Typically the main func;on is defined in terms of other func;ons, which in turn are defined in terms of s;ll more func;ons, un;l at the boEom level the func;ons are language primi;ves.” John Hughes – “Why Func;onal Programming MaEers”
- 45. F#, ok
- 46. but
- 47. C# ?!?!
- 48. C# is an imperaWve language, dude
- 49. agreed
- 50. but
- 51. how about mixing paradigms?
- 52. again, …
- 53. less code
- 54. less bugs
- 56. expressiveness
- 57. say what
- 58. IEnumerable<int> FilterAndSortYetAgain(IEnumerable<int> numbers) { return from n in numbers where n.IsEven() orderby n select n; }
- 59. not how
- 60. IEnumerable<int> FilterAndSort(IEnumerable<int> numbers) { var evens = new List<int>(); foreach (var i in numbers) { if (i % 2 == 0) { evens.Add(i); } } evens.Sort(); return evens; }
- 61. ok
- 62. what else?
- 63. funcWons are kind of a big deal
- 64. principle of least surprise
- 65. immutability
- 66. no side-‐effects
- 67. lazy evaluaWon
- 69. etc
- 70. but how?
- 72. IEnumerable<int> FilterAndSortYetAgain(IEnumerable<int> numbers) { return from n in numbers where n.IsEven() orderby n select n; }
- 73. public staWc class MyExtensions { public staWc bool IsEven(this int number) { return number % 2 == 0; } }
- 74. public staWc class MyExtensions { public staWc bool IsEven(this int number) { return number % 2 == 0; } }
- 75. LINQ
- 76. IEnumerable<int> FilterAndSortStrikingBack(IEnumerable<int> numbers) { return numbers .Where(i => i % 2 == 0) .OrderBy(i => i); }
- 77. a nice way to query stuff
- 78. series of extension methods
- 79. Select() Skip() Take() OrderBy() GroupBy() Where() …
- 80. +
- 81. syntacWc sugar
- 82. IEnumerable<int> FilterAndSortStrikingBack(IEnumerable<int> numbers) { return numbers .Where(i => i % 2 == 0) .OrderBy(i => i); }
- 83. IEnumerable<int> FilterAndSortEvenBe@er(IEnumerable<int> numbers) { return from n in numbers where n % 2 == 0 orderby n select n; }
- 84. laziness
- 85. iterators
- 86. IEnumerable<int> Fibonacci() { yield return 0; yield return 1; var previous = 0; var current = 1; while (true) { var next = previous + current; yield return next; previous = current; current = next; } }
- 87. IEnumerable<int> Fibonacci() { yield return 0; yield return 1; var previous = 0; var current = 1; while (true) { var next = previous + current; yield return next; previous = current; current = next; } }
- 88. IEnumerable<int> Fibonacci() { yield return 0; yield return 1; var previous = 0; var current = 1; while (true) { var next = previous + current; yield return next; previous = current; current = next; } }
- 89. watch out: performance side effects …
- 90. lambdas
- 91. IEnumerable<int> FilterAndSortStrikingBack(IEnumerable<int> numbers) { return numbers .Where(i => i % 2 == 0) .OrderBy(i => i); }
- 92. syntacWc sugar
- 94. IEnumerable<int> FilterAndSortStrikingBackAgain (IEnumerable<int> numbers) { return numbers.Where(delegate(int number) { return number%2 == 0; }); }
- 95. delegates
- 96. funcWon pointers
- 99. one more thing
- 100. don’t forget OO
- 101. you might be tempted
- 103. (from item in order.Items select item.Price).Max();
- 104. duplicaWon
- 105. encapsulaWon
- 106. all right
- 107. that’s about it for today I guess
- 108. quesWons?
- 109. thank you!