Opinionated Code

Erica Sadun

Transcript

1. OPINIONATED CODE
2. OPINIONATED CODE
3. WHY STYLE? ‣ ‣ ‣ ‣
4. WHY STYLE? ‣ ‣ ‣ ‣
5. WHY STYLE? ‣ Code should be invisible ‣ ‣ ‣
6. WHY STYLE? ‣ Code should be invisible ‣ ‣ ‣
7. WHY STYLE? ‣ Code should be invisible ‣ Focus on meaning ‣ ‣
8. WHY STYLE? ‣ Code should be invisible ‣ Focus on meaning ‣ Reduce cognitive load ‣
9. WHY STYLE? ‣ Code should be invisible ‣ Focus on meaning ‣ Reduce cognitive load ‣
10. WHY STYLE? ‣ Code should be invisible ‣ Focus on meaning ‣ Reduce cognitive load ‣ Uniformity
11. WHY STYLE? ‣ Code should be invisible ‣ Focus on meaning ‣ Reduce cognitive load ‣ Uniformity
12. WHY STYLE? CONSISTENT RULES PRODUCE CONSISTENT CODE
13. WHY STYLE? CONSISTENT RULES PRODUCE CONSISTENT CODE
14. STYLE EXAMPLE 1 SEMICOLONS
15. SEMICOLONS ‣ Don't C-Style your code ‣
16. SEMICOLONS func myFunction() { statement1; statement2; statement3; }
17. SEMICOLONS func myFunction() { statement1; statement2; statement3; }
18. SEMICOLONS ‣ Don't C-Style your code ‣ Semicolons are "statement glue"
19. // duplicates x++ defer { x = x + 1 }; return x SEMICOLONS
20. // duplicates x++ defer { x = x + 1 }; return x SEMICOLONS
21. // duplicates x++ defer { x = x + 1 }; return x SEMICOLONS
22. SEMICOLONS // Establish new drawing context UIGraphicsPushContext(context); defer { UIGraphicsPopContext() }
23. STYLE EXAMPLE 2 NUMBER LITERALS
24. FORMATTING NUMBER LITERALS ‣ Add Underscores ‣
25. UNDERSCORES let largeInteger = 1732500 // harder to inspect let largeInteger = 1_732_500 // easily reviewed
26. FORMATTING NUMBER LITERALS ‣ Add Underscores ‣ Decimal: 3, Hex: 2, Octal: 4, Binary: 8
27. UNDERSCORES let largeInteger = 0xffffff // 5 f's or 6? let largeInteger = 0xff_ff_ff // easily reviewed
28. STYLE EXAMPLE 3 TYPING
29. TYPING VS CONSTRUCTORS ‣ ‣
30. TYPING VS CONSTRUCTORS ‣ Prefer Typing for Collections ‣
31. TYPING var array: [String] = [] // yes var dictionary: [AnyHashable: Any] = [:] // yes var aSet: Set<String> = [] // yes var array = [String]() // no var array = Array<String>() // no var dictionary = [AnyHashable: Any]() // no var dictionary = Dictionary<AnyHashable: Any>() // no var aSet = Set<String>() // no
32. TYPING var array: [String] = [] // yes var dictionary: [AnyHashable: Any] = [:] // yes var aSet: Set<String> = [] // yes var array = [String]() // no var array = Array<String>() // no var dictionary = [AnyHashable: Any]() // no var dictionary = Dictionary<AnyHashable: Any>() // no var aSet = Set<String>() // no
33. TYPING var array: [String] = ["a", "b", "c"] var aSet: Set<String> = ["a", "b", "c"] var array = [String]() // no array = ["a", "b", "c"] var array = Set<String>() // no array = ["a", "b", "c"]
34. TYPING VS CONSTRUCTORS ‣ Prefer Typing for Collections ‣ Prefer Meaningful Constructors
35. TYPING let point = CGPoint(x: 15, y: 20) // fine let point: CGPoint = CGPoint(x: 15, y: 20) // wordy
36. TYPING let point = CGPoint(x: 15, y: 20) // fine let point: CGPoint = CGPoint(x: 15, y: 20) // wordy
37. TYPING let point = CGPoint(x: 15, y: 20) // fine let point: CGPoint = CGPoint(x: 15, y: 20) // wordy
38. STYLE EXAMPLE 4 OPTIONAL SUGAR
39. OPTIONAL SUGAR ‣ Prefer sugared use (`x?`) ‣ Avoid explicit cases (`.some(x)`)
40. OPTIONAL SUGAR switch (firstOptional , secondOptional) { // no case let (.some(first), .some(second)): ... ... default: break } switch (firstOptional , secondOptional) { // yes case let (first?, second?): ... ... default: break }
41. OPTIONAL SUGAR let optItems: [Int?] = [1, nil, 5, 2, 4, nil] for case let item? in optItems { print(item) } for case .some(let item) in optItems { print(item) }
42. OPTIONAL SUGAR let optItems: [Int?] = [1, nil, 5, 2, 4, nil] for case let item? in optItems { // no print(item) } for item in optItems.flatMap({ $0 }) { // yes print(item) }
43. OPTIONAL SUGAR enum Result<T> { case success(T), error(Error) } guard case let .success(value) = result else { return } // yes print(value)
44. LESSONS LEARNED
45. Focus on Meaning Lessons learned
46. Focus on Meaning Be Consistent Lessons learned
47. Focus on Meaning Be Consistent Be Uniform Lessons learned
48. Focus on Meaning Be Consistent Be Uniform Develop Swift in Swift Lessons learned
49. Focus on Meaning Simplify Inspection Be Consistent Be Uniform Develop Swift in Swift Lessons learned
50. Focus on Meaning Simplify Inspection Think Readable Be Consistent Be Uniform Develop Swift in Swift Lessons learned
51. Focus on Meaning Simplify Inspection Think Readable Prefer Sugar Be Consistent Be Uniform Develop Swift in Swift Lessons learned
52. Focus on Meaning Simplify Inspection Think Readable Prefer Sugar Be Consistent Be Uniform Develop Swift in Swift Avoid Tunnel Vision Lessons learned
53. https://pragprog.com/book/esswift/swift-style "It’s not just the compiler that needs to read your code” — Erica Sadun, Swift Style.
54. http://ericasadun.com erica@ericasadun.com @ericasadun https://pragprog.com/book/esswift/swift-style Q&A