Techniques to write DSLs in Swift

Transcript

1. “Clean code reads like well-written prose” – Grady Booch
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4. @implementation Subscription - (id)init { self = [super init]; if (!self) return nil; self.state = @"pending"; } - (void)activateWithCode:(NSString *)activationCode { if ([self.state isEqualToString:@"pending"] && [self.code isEqualToString:activationCode]) { self.state = @"active"; } } - (void)suspend { if ([self.state isEqualToString:@"active"]) { [self stopBilling]; } } @end IMPLEMENTATION
5. LSStateMachine *sm = [[LSStateMachine alloc] init]; LSState *s1 = [[LSState alloc] initWithName:@"pending"]; LSState *s2 = [[LSState alloc] initWithName:@"active"]; [sm addState:s1]; [sm addState:s2]; LSEvent *e1 = [[LSEvent alloc] initWithName:@"activate"]; LSTransition *t1 = [[LSTransition alloc] initWithEvent:e1 from:s1 to:s2]; [sm addTransition:t1]; ABSTRACTION
6. TECHNIQUES TO WRITE DSLs IN OBJECTIVE-C
7. TECHNIQUES TO WRITE DSLs IN SWIFT
8. LUIS SOLANO @luisobo
9. DOMAIN-SPECIFIC LANGUAGE
10. LANGUAGE PROGRAMMING
11. SPECIFIC CONSTRAINT
12. TO A CERTAIN DOMAIN CERTAIN TYPE OF PROBLEM
13. LSStateMachine *sm = [[LSStateMachine alloc] init]; LSState *s1 = [[LSState alloc] initWithName:@"pending"]; LSState *s2 = [[LSState alloc] initWithName:@"active"]; [sm addState:s1]; [sm addState:s2]; LSEvent *e1 = [[LSEvent alloc] initWithName:@"activate"]; LSTransition *t1 = [[LSTransition alloc] initWithEvent:e1 from:s1 to:s2]; [sm addTransition:t1]; ABSTRACTION
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15. LSStateMachine *sm = [[LSStateMachine alloc] init]; LSState *s1 = [[LSState alloc] initWithName:@"pending"]; LSState *s2 = [[LSState alloc] initWithName:@"active"]; [sm addState:s1]; [sm addState:s2]; LSEvent *e1 = [[LSEvent alloc] initWithName:@"activate"]; LSTransition *t1 = [[LSTransition alloc] initWithEvent:e1 from:s1 to:s2]; [sm addTransition:t1]; ABSTRACTION
16. sm.when("activate", transitionFrom: "pending", to: "active") DSL
17. DSL luisobo/StateMachine
18. sm.when("activate", transitionFrom: "pending", to: "active") sm.when("suspend", transitionFrom: "active", to: "suspended") sm.when("unsuspend", transitionFrom: "suspended", to: "active") sm.when("terminate", transitionFrom: "active", to: "terminated") sm.when("terminate", transitionFrom: "suspended", to: "terminated") ! sm.before("terminate") { subscription in subscription.terminatedAt = NSDate.date() } ! sm.before("suspend") { subscription in subscription.stopBilling() } DSL
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20. asjdañlksjdlaksjdñlak asjdañlksjdla asjdañlksjdlaksjdñlak asjdañlksjdla asjdañlksjdlaksjdñlak asjdañlksjdla asjdañlksjdlaksjdñlak asjdañlksjdla Semantic model Domain-specfic language
21. DECLARATIVE
22. imperative
23. imperative is fine
24. imperative works
25. my brain
26. my brain cannot handle imperative programming’s scale
27. DECLARATIVE
28. INTERNAL EXTERNAL INTERNAL
29. DSL? WHY TO
30. DSL? WHEN TO
31. DSL? HOW TO
32. SWIFT METHODS luisobo/StateMachine sm.when("activate", transitionFrom: "pending", to: "active")
33. LSStateMachine *sm = [[LSStateMachine alloc] init]; LSState *s1 = [[LSState alloc] initWithName:@"pending"]; LSState *s2 = [[LSState alloc] initWithName:@"active"]; [sm addState:s1]; [sm addState:s2]; LSEvent *e1 = [[LSEvent alloc] initWithName:@"activate"]; LSTransition *t1 = [[LSTransition alloc] initWithEvent:e1 from:s1 to:s2]; [sm addTransition:t1]; SWIFT METHODS luisobo/StateMachine
34. SWIFT METHODS luisobo/StateMachine sm.when("activate", transitionFrom: "pending", to: "active")
35. METHOD CHAINING stubRequest("GET", "http://hello.com/"). andReturn(200).withBody("hola"); luisobo/Nocilla
36. stubRequest("POST", "http://hello.com"). withHeader("Content-Type", "text/plain"). withHeader("X-MY-AWESOME-HEADER", "sisisi"). withBody("Adios!"). andReturn(200). withHeader("Content-Type", "text/plain"). withBody("hola"); METHOD CHAINING luisobo/Nocilla
37. EXTENSIONS state.should.eq(“active”)
38. EXTENSIONS extension NSObject { var should:Matcher { return Matcher() } }
39. [1, 2, 3] [1: “one”, 2: “two”, 3: “three”] ARRAY AND DICTIONARY LITERALS
40. stubRequest("GET", “http://hello.com"). withHeaders([“Content-Type": “text/plain", "X-MY-AWESOME-HEADER" : “YEAH!”]). andReturn(200); luisobo/Nocilla ARRAY AND DICTIONARY LITERALS
41. .adjustTemperature(24.5).at(“nine"). USING LITERALS WITH YOUR TYPES
42. func adjustTemperature(to: Temp) -> Thermostat func at(time: NSDate) -> Thermostat USING LITERALS WITH YOUR TYPES
43. protocol FloatLiteralConvertible { ! typealias FloatLiteralType ! class func convertFromFloatLiteral(value: FloatLiteralType) -> Self ! } USING LITERALS WITH YOUR TYPES
44. extension Temp: FloatLiteralConvertible { typealias FloatLiteralType = Double class func convertFromFloatLiteral(value: Double) -> Temp { return Temp(degrees: value) } } USING LITERALS WITH YOUR TYPES
45. IntegerLiteralConvertible FloatLiteralConvertible StringLiteralConvertible LogicValue StringInterpolationConvertible ArrayLiteralConvertible DictionaryLiteralConvertible USING LITERALS WITH YOUR TYPES 1 3.5 “foo” if myValue “hello \(value)” [1, 2, 3] [“one”: 1, “two”: 2]
46. BLOCKS sm.before("terminate") { subscription in subscription.terminatedAt = NSDate.date() } luisobo/StateMachine
47. BLOCKS FOR CONTEXT User.defineFactory { f in f["foo"] = "bar" f["password"] = "hunter2" } luisobo/Defactory
48. SYNTACTIC SUGAR o.com”).with.body(“Hola”).and.return(200) luisobo/Nocilla
49. OPERATOR OVERLOAD ^= *= * % + - / <<= ||= << || |= <= >>= !== >= ~= | >> < += &&= %= ... -= &% /= && &* &+ &- &/ === == & .. ^ > &= != ~ ! -- ++ - + -- ++
50. OPERATOR OVERLOAD let s: Speed = 100.meters / 5.seconds
51. CUSTOM OPERATORS / = - + * % < > ! & | ^ . ~.
52. CUSTOM OPERATORS operator infix =>> {}
53. =>>
54. stubRequest("GET","http://hello.com/") luisobo/Nocilla stubRequest(method:String, url:String)
55. stubRequest("GET", "http://hello.com/") stubRequest(“GET", regex(“http://.*\.com”)) luisobo/Nocilla stubRequest(method:String, url:AnyObject)
56. stubRequest("POST", NSObject()); stubRequest(“POST”, []); luisobo/Nocilla stubRequest(method:String, url:AnyObject)
57. protocol Matchable { func matcher() -> Matcher } ADD PROTOCOL TO EXISTING CLASS luisobo/Nocilla
58. extension NSString: Matchable { func matcher() -> Matcher { return StringMatcher(pattern: self) } } ADD PROTOCOL TO EXISTING CLASS
59. ADD PROTOCOL TO EXISTING CLASS extension NSRegularExpression: Matchable { func matcher() -> Matcher { return RegexMatcher(pattern: self) } }
60. ADD PROTOCOL TO EXISTING CLASS stubRequest("GET", "http://hello.com/") stubRequest(“GET", regex(“http://.*\.com”)) luisobo/Nocilla stubRequest(method:String, url:Matcheable)
61. stubRequest("POST", NSObject()]); stubRequest(“POST”,[]]); stubRequest(method:String, url:Matcheable) ADD PROTOCOL TO EXISTING CLASS luisobo/Nocilla
63. Thin layer on top of an abstraction. Limited expressiveness and domain focus. Make your code more maintainable Developer happiness Improved communication Fewer bugs! As seen in TV
64. ! ! Domain-specific languages by Martin Fowler brain photo: flickr/_DJ_ redacted font: github/christiannaths Nocilla: github/luisobo StateMachine: github/luisobo Defactory: github/luisobo Kiwi: github/kiwi-bdd metamacros.h github/jspahrsummers THANKS! @luisobo