Code Generators In Swift (Part 2)

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Code Generators in Swift by Paul Taykalo, Stanfy Code Generators in Swift, #Cocoaheads, Minsk 1

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Code generation Code Generators in Swift, #Cocoaheads, Minsk 2

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Code generation or Automatic Programming In computer science, the term automatic programming identiﬁes a type of computer programming in which some mechanism generates a computer program to allow human programmers to write the code at a higher abstraction level — Wikipedia Code Generators in Swift, #Cocoaheads, Minsk 3

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Generators in general Code Generators in Swift, #Cocoaheads, Minsk 4

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Our main interest today * Code Generators in Swift, #Cocoaheads, Minsk 5

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Our goals Code Generators in Swift, #Cocoaheads, Minsk 6

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Write less code Code Generators in Swift, #Cocoaheads, Minsk 7

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Automate Repetitive Operations Code Generators in Swift, #Cocoaheads, Minsk 8

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Save time Make everyone happy Code Generators in Swift, #Cocoaheads, Minsk 9

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Uniform structure Code Generators in Swift, #Cocoaheads, Minsk 10

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Error Scalability Code Generators in Swift, #Cocoaheads, Minsk 11

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Platform Scalability Code Generators in Swift, #Cocoaheads, Minsk 12

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When should we write one? Code Generators in Swift, #Cocoaheads, Minsk 13

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When should we write one? ✅ Structure is well deﬁned Code Generators in Swift, #Cocoaheads, Minsk 14

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When should we write one? ✅ Structure is well deﬁned ✅ Number of special cases is low ✅ Uniform structure Code Generators in Swift, #Cocoaheads, Minsk 15

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When should we write one? ✅ Structure is well deﬁned ✅ Number of special cases is low ✅ Uniform structure ✅ One Layer of Abstraction Code Generators in Swift, #Cocoaheads, Minsk 16

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When should we write one? ✅ Structure is well deﬁned ✅ Number of special cases is low ✅ Uniform structure ✅ One Layer of Abstraction ✅ It's time efﬁcient Code Generators in Swift, #Cocoaheads, Minsk 17

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Time efficiency rule Code Generators in Swift, #Cocoaheads, Minsk 18

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Time efficiency rule Code Generators in Swift, #Cocoaheads, Minsk 19

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Time efficiency rule examples Code Generators in Swift, #Cocoaheads, Minsk 20

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Time efficiency rule examples Code Generators in Swift, #Cocoaheads, Minsk 21

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Flow time is limited. Simple operations should take small amount of time Code Generators in Swift, #Cocoaheads, Minsk 22

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Code Generators in Swift, #Cocoaheads, Minsk 23

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Source Code Generators in Swift, #Cocoaheads, Minsk 24

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Generator Source DSL Code Generators in Swift, #Cocoaheads, Minsk 25

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Generator Source Swift Code Code Generators in Swift, #Cocoaheads, Minsk 26

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Let's back to swift Code Generators in Swift, #Cocoaheads, Minsk 27

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But before that What so special in code generators for Swift? Code Generators in Swift, #Cocoaheads, Minsk 28

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What so special in code generators for Swift? • No Runtime • Static Typing • No simple way to get types in runtime* • Hard to get metainformation at runtime* Code Generators in Swift, #Cocoaheads, Minsk 29

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Examples Code Generators in Swift, #Cocoaheads, Minsk 30

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Code Snippets Code Generators in Swift, #Cocoaheads, Minsk 31

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Code Generators in Swift, #Cocoaheads, Minsk 32

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Xcode File Templates Code Generators in Swift, #Cocoaheads, Minsk 33

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Project Templates Code Generators in Swift, #Cocoaheads, Minsk 34

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Bit more complex examples Code Generators in Swift, #Cocoaheads, Minsk 35

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Swagger • Source Language: DSL in YAML / JSON • Written In: Java • Generates: Everything http://swagger.io/ Code Generators in Swift, #Cocoaheads, Minsk 36

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Cuckoo • Source Language: Swift Code • Written in: Swift • Generates: Swift (Mocks) https://github.com/SwiftKit/ Cuckoo Code Generators in Swift, #Cocoaheads, Minsk 37

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Cuckoo let mock = MockGreeter() stub(mock) { stub in when(stub.greetWithMessage("Hello world")).then { message in print(message) } } Code Generators in Swift, #Cocoaheads, Minsk 38

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VIPER Module Generator • Source Language: String • Written in: Ruby • Generates: Swift, Objective-C https://github.com/teambox/ viper-module-generator Code Generators in Swift, #Cocoaheads, Minsk 39

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Generamba • Source Language: Ruby (DSL) • Written in: Ruby • Generates: Swift, Objective-C, Xcode Project https://github.com/rambler-digital-solutions/ Generamba Code Generators in Swift, #Cocoaheads, Minsk 40

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Protobuf Source: Protocol Buffers Language Written in: * Generates: Swift, Any Supported Language https://github.com/alexeyxo/protobuf-swift https://github.com/google/protobuf Code Generators in Swift, #Cocoaheads, Minsk 41

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SwiftGen Source: Xcode Files Written in : Swift Generates: Enums for resources https://github.com/AliSoftware/SwiftGen Code Generators in Swift, #Cocoaheads, Minsk 42

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SwiftGen // The Image type below is typealias'ed to UIImage on iOS and NSImage on OSX enum Asset: String { case Green_Apple = "Green-Apple" case Red_Apple = "Red apple" case _2_Pears = "2-pears" var image: Image { return Image(asset: self) } } extension Image { convenience init!(asset: Asset) { self.init(named: asset.rawValue) } } Code Generators in Swift, #Cocoaheads, Minsk 43

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R Source: Xcode Project Files Written in : Swift Generates: Enums for resources https://github.com/mac-cain13/R.swift Code Generators in Swift, #Cocoaheads, Minsk 44

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R Code Generators in Swift, #Cocoaheads, Minsk 45

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Helium Source : DSL in Groovy Written in : JVM Languages Java/Kotlin/Groovy Generates: Java Library, API Client, Swift, Objective-C https://github.com/stanfy/ helium Code Generators in Swift, #Cocoaheads, Minsk 46

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If you decided to create on Code Generators in Swift, #Cocoaheads, Minsk 47

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Templates, DSL Code Generators in Swift, #Cocoaheads, Minsk 48

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SourceKitten Code Generators in Swift, #Cocoaheads, Minsk 49

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SourceKitten [{ "descriptionKey" : "advancedBy(n: Distance)", "associatedUSRs" : "s:FSi10advancedByFSiFSiSi ", "kind" : "source.lang.swift.decl.function.method.instance", "sourcetext" : "advancedBy(<#T##n: Distance##Distance#>)", "context" : "source.codecompletion.context.thisclass", "typeName" : "Int", "moduleName" : "Swift", "name" : "advancedBy(n: Distance)" }, Code Generators in Swift, #Cocoaheads, Minsk 50

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SourceKitten sourcekitten structure --text "struct A { func b() {} } { "key.substructure" : [ { "key.kind" : "source.lang.swift.decl.struct", "key.offset" : 0, "key.nameoffset" : 7, "key.namelength" : 1, "key.bodyoffset" : 10, "key.bodylength" : 13, "key.length" : 24, "key.substructure" : [ ... } ], "key.offset" : 0, "key.diagnostic_stage" : "source.diagnostic.stage.swift.parse", "key.length" : 24 } Code Generators in Swift, #Cocoaheads, Minsk 51

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Tips and Tricks Code Generators in Swift, #Cocoaheads, Minsk 52

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Don't go too deep Code Generators in Swift, #Cocoaheads, Minsk 53

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Simple is better than easy Code Generators in Swift, #Cocoaheads, Minsk 54

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Simple is better than easy • Simple is easier to support and understand Code Generators in Swift, #Cocoaheads, Minsk 55

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Simple is better than easy • Simple is easier to support and understand • Easy one can be complex but easy to use Code Generators in Swift, #Cocoaheads, Minsk 56

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Simple is better than easy • Simple is easier to support and understand • Easy one can be complex but easy to use • Use templates Code Generators in Swift, #Cocoaheads, Minsk 57

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Check reality Code Generators in Swift, #Cocoaheads, Minsk 58

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Check reality • Ask if this tool is really needed? • Ask other people too Code Generators in Swift, #Cocoaheads, Minsk 59

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For the future generations • Document • Open Source Code Generators in Swift, #Cocoaheads, Minsk 60

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Our results Code Generators in Swift, #Cocoaheads, Minsk 61

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Source type 'Shop' message { shop_id 'string' image 'string' name 'string' description 'string' currency 'string' optional service_charge 'AdditionalCharges' optional payment_methods(type:'PaymentMethod') { sequence true required false } } Code Generators in Swift, #Cocoaheads, Minsk 62

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Source type "dayOfWeek" spec { constraints("string") { enumeration 'sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat' } } Code Generators in Swift, #Cocoaheads, Minsk 63

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Entities generation public enum DayOfWeek: String { case Sun = "sun" case Mon = "mon" case Tue = "tue" case Wed = "wed" case Thu = "thu" case Fri = "fri" case Sat = "sat" } Code Generators in Swift, #Cocoaheads, Minsk 64

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Entities generation public struct Shop { public let shopId: String public let image: String public let name: String public let description: String public let currency: String? public let serviceCharge: AdditionalCharges? public let paymentMethods: [PaymentMethod]? } Code Generators in Swift, #Cocoaheads, Minsk 65

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Equatable // MARK: - Shop Equatable public func == (lhs: Shop, rhs: Shop) -> Bool { return lhs.shopId == rhs.shopId && lhs.image == rhs.image && lhs.name == rhs.name && lhs.description == rhs.description && lhs.currency == rhs.currency && lhs.serviceCharge == rhs.serviceCharge && lhs.paymentMethods == rhs.paymentMethods } Code Generators in Swift, #Cocoaheads, Minsk 66

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Mappings generation extension DayOfWeek: Decodable {} extension Shop: Decodable { public static func decode(json: AnyObject) throws -> Shop { return try Shop( internalId: json =>? "internal_id" , shopId: json => "shop_id" , image: json => "image" , name: json => "name" , description: json => "description" , currency: json =>? "currency" , deliveryCharge: json =>? "delivery_charge" , paymentMethods: json =>? "payment_methods" ) } } Code Generators in Swift, #Cocoaheads, Minsk 67

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Random structures generation extension Shop: Random { static func random() -> Shop { return restrictedRandom() } } Code Generators in Swift, #Cocoaheads, Minsk 68

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Random structures generation extension Shop: Random { static func restrictedRandom( shopId: String = .random(), image: String = .random(), name: String = .random() ... ) -> Shop { return Shop( shopId: shopId, image: image, name: name ... ) } } Code Generators in Swift, #Cocoaheads, Minsk 69

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Structures updates extension Shop { func updated( shopId: Optional = nil, image: Optional = nil, name: Optional = nil ... ) -> Shop { return Shop( shopId:shopId ?? self.shopId, image:image ?? self.image, name:name ?? self.name ... ) } } Code Generators in Swift, #Cocoaheads, Minsk 70

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Generated code in action // Only shipId will be set up let validShop = Shop.restrictedRandom( shopId: "SE2016", currency: "UAH" ) // Everything will be copied but 'shopID' property let anotherShop = validShop.updated(shopId:"123") // If we want to set up nil value let notSavedYet = validShop.updated(internalId: Optional(nil)) let notSavedYet2 = validShop.updated(internalId: .Some(nil)) Code Generators in Swift, #Cocoaheads, Minsk 71

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From one source type 'Shop' message { shop_id 'string' image 'string' name 'string' description 'string' currency 'string' optional service_charge 'AdditionalCharges' optional payment_methods(type:'PaymentMethod') { sequence true required false } } Code Generators in Swift, #Cocoaheads, Minsk 72

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Sum up • Code generators are here Code Generators in Swift, #Cocoaheads, Minsk 73

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Sum up • Engineering approach > Art Code Generators in Swift, #Cocoaheads, Minsk 74

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Sum up • There're always things to automate • Code generation is one of the multiple options Code Generators in Swift, #Cocoaheads, Minsk 75

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Sum up • Write your own if it worth it • Please don't write another one-time-complex generator • Document well Code Generators in Swift, #Cocoaheads, Minsk 76

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Thank you Code Generators in Swift, #Cocoaheads, Minsk 77

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Code Generators in Swift by Paul Taykalo, Stanfy @TT_Kilew Code Generators in Swift, #Cocoaheads, Minsk 78

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The end Code Generators in Swift, #Cocoaheads, Minsk 79