継続渡しと契約による設計 / 20190319 #tryswift_pre

【増枠/increase】try! Swift Pre Talks 2019 - connpass
https://tryswifttokyo-aftertalks.connpass.com/event/120987/
での発表資料です。

Transcript

1. ܧଓ౉͠ͱܖ໿ʹΑΔઃܭ
   Continuation-Passing Style and Design By Contract
   by.
   2019/3/19 try! Swift Pre Talks 2019
   1
   

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2. takasek
   @takasek
   Works
   OSS: ActionClosurable౳
   App: PasteTheType
   Articles
   ʮίϯύΠϧΤϥʔ΍ϥϯλΠϜΤϥʔΛ௚͍ͯ͘͠
   ͚ͩͰiOSΞϓϦͷ࡞Γํ͕Θ͔ΔϓϩδΣΫτʯ
   ʮ͓લΒ͕ModelͱݺͿΞϨΛͳΜͱݺͿ΂͖͔ʯ
   ʮiOSΞϓϦઃܭύλʔϯೖ໳ʯʢڞஶʣ
   2
   

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3. ʮiOSΞϓϦઃܭύλʔϯೖ໳ʯ
   ޷ධൃചதʂ
   https://peaks.cc/takasek/iOS_architecture
   takasek୲౰ষ
   ୈ1ষʮઃܭ͢Δͱ͍͏͜ͱʯ
   ୈ2ষʮઃܭʹύλʔϯΛద༻͢Δલʹʯ
   ୈ3ষʮSwiftΒ͘͠ઃܭ͢Δʯ
   ୈ4ষʮΞʔΩςΫνϟͷύλʔϯΛௗᛌ͢
   Δʯ
   3
   

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4. ܧଓ౉͠
   Continuation-
   Passing Style(CPS)
   4
   

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5. // Without CPS
   func doSomething(i: Int) -> String {
   sleep(100)
   return "\(i)"
   }
   // With CPS
   func doSomething(i: Int, completion: @escaping (String) -> Void) {
   DispatchQueue.global().async {
   sleep(100)
   completion("\(i)")
   }
   }
   5
   

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6. !
   6
   

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7. func doSomething(
   i: Int,
   completion: @escaping (String) -> Void
   )
   ͜ͷΠϯλϑΣʔεʹ͸ɺخ͘͠ͳ͍఺͕͋Γ·͢
   7
   

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8. ʮ͋ͬɺ࿩͸ಡΊͨʯ
   8
   

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9. ʮίʔϧόοΫ஍ࠈͷ࿩Ͱ͠ΐʯ
   9
   

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10. ҧ͍·͢
    10
    

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11. ܖ໿ʹΑΔ
    ઃܭ
    Design By Contract
    11
    

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12. ܖ໿ʹΑΔઃܭ
    Design By Contract
    ΦϒδΣΫτࢦ޲Λ޿Ίͨݚڀऀ
    όʔτϥϯυɾϝΠϠʔʹΑΔɺ
    ৴པੑͷߴ͍γεςϜΛ
    ߏங͢ΔͨΊͷΞΠσΞ
    12
    

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13. ܖ໿ʹΑΔઃܭ
    ͋Δϧʔνϯ͕ɺݺ͹ΕΔ૬खͱͷؒͰऔΓަΘܾ͢Ί͝ͱΛʮද໌ʯ͢Δ
    • ࣄલ৚݅ɿ
    ݺͿଆ͕͜ͷ৚݅Λอূ͢Δ৔߹ͷΈɺϧʔνϯ͸ॲཧΛਖ਼͘͠ߦ͏
    Ҿ਺ͷܕͳͲͰදݱՄೳ
    • ࣄޙ৚݅ɿ
    ࣄલ৚͕݅कΒΕ͍ͯͨΒɺϧʔνϯͷ࣮ߦ݁Ռ͕อূ͢Δ৚݅
    ໭Γ஋ͷܕͳͲͰදݱՄೳ
    ࣄલ৚͕݅ഁΒΕɺࣄޙ৚݅ΛकΕͳ͍৔߹͸ྫ֎͕ൃੜ͢Δ
    • ෆม৚݅ ʹ͍ͭͯ͸ࠓճ͸লུ
    13
    

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14. ίʔυͱද໌ͷ۩ମྫ
    func half(of i: Int) throws -> Int {
    assert(i.isMultiple(of: 2))
    if !i.isMultiple(of: 2) { throw Error.isOdd }
    return i / 2
    }
    • ࣄલ৚݅:
    • Int ͔͠ड͚͚ͭ·ͤΜ
    • ۮ਺͔͠ड͚͚ͭ·ͤΜ (ܕͱͯ͠දݱෆೳ)
    • ࣄޙ৚݅: ඞͣ Int Λฦ͠·͢
    • ྫ֎: ۮ਺Ͱͳ͔ͬͨ৔߹͸ྫ֎Λ౤͛·͢
    14
    

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15. ʮܖ໿ʹΑΔઃܭʯͷ࣮ݱͷͨΊʹɺSwiftͷܕ෇͚͸େ͖͘໾ཱ͍ͬͯΔ
    15
    

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16. ͯ͞
    16
    

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17. func half(of i: Int) throws -> Int {
    if !i.isMultiple(of: 2) {
    throw Error.isOdd
    }
    return i / 2
    }
    ͜ΕΛCPSʹม׵ͯ͠Έ·͠ΐ͏
    17
    

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18. func half(of i: Int, completion: (Int) -> Void) {
    if !i.isMultiple(of: 2) {
    return
    }
    completion(i / 2)
    }
    18
    

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19. View Slide

20. OK, ح਺ͷ৔߹΋
    ֬ೝ͠Α͏ʂ
    20
    

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21. View Slide

22. ݺ͹Εͳ͍…ʁ
    22
    

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23. View Slide

24. completionͷ
    ݺͼ࿙Ε
    24
    

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25. func half(of i: Int, completion: (Int) -> Void) {
    if !i.isMultiple(of: 2) {
    return //
    !
    }
    completion(i / 2)
    }
    25
    

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26. enum Result {
    case success(T)
    case error(Error)
    }
    func half(of i: Int, completion: (Result) -> Void) {
    if !i.isMultiple(of: 2) {
    return //
    !
    }
    completion(.success(i / 2))
    }
    26
    

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27. enum Result {
    case success(T)
    case error(Error)
    }
    func half(of i: Int, completion: (Result) -> Void) {
    if !i.isMultiple(of: 2) {
    completion(.error(.isOdd)) //
    }
    completion(.success(i / 2))
    }
    27
    

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28. ௚ͬͨʂ
    ΋͏Ұ౓ڍಈΛ
    ֬ೝ͠Α͏ʂ
    28
    

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29. View Slide

30. 2౓ݺ͹Ε͍ͯΔ
    …ͩͱ…ʁ
    30
    

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31. func half(of i: Int, completion: (Result) -> Void) {
    if !i.isMultiple(of: 2) {
    completion(.error(.isOdd))
    //
    !
    }
    completion(.success(i / 2))
    }
    31
    

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32. func half(of i: Int, completion: (Result) -> Void) {
    if !i.isMultiple(of: 2) {
    completion(.error(.isOdd))
    return //
    !
    }
    completion(.success(i / 2))
    }
    32
    

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33. ܧଓ౉͠ελΠϧΛ࢖͏ͱ
    ੩తܕ෇͚ͷԸܙΛ
    ड͚ΒΕͳ͍
    33
    

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34. ͳͥͳͷ͔
    ໭Γ஋ͷܕʹΑͬͯ
    ࣄޙ৚݅ΛදݱͰ͖ͳ͍͔Β
    (T, (U) -> Void) -> Void
    Void͸࠷ऑͷࣄޙ৚݅
    34
    

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35. Ͳ͏͢Ε͹͍͍͔
    ໭Γ஋ͷܕʹΑͬͯ
    ࣄޙ৚݅Λදݱ͢Ε͹͍͍
    (T) -> XXX
    ʮ͍ͣΕ݁Ռ͕ಘΒΕΔʯ͜ͱΛܕ෇͚ͰࣔͤΕ͹ɺ
    ඇಉظॲཧͰ΋໭Γ஋Λػೳͤ͞ΒΕΔ
    35
    

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36. func half(of i: Int) -> RxSwift.Single {
    if !i.isMultiple(of: 2) {
    return .error(Error.isOdd)
    }
    return .just(i / 2)
    }
    ͜ΕͳΒ੩తܕ෇͚ͷԸܙΛड͚ͭͭɺ
    ʮඇಉظͰ͋Δ͜ͱʯΛදݱͰ͖Δ
    36
    

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37. • Promise(Future) ύλʔϯ
    • PromiseK
    • Hydra
    • RxSwift
    • etc
    • async/await
    • comming soon in Swift 5.x!?
    • ͜ͷݴޠ࢓༷Λϕʔεʹ Future ܕΛߏஙՄೳ
    CPSΛશ໘తʹஔ͖͔͑Մೳ͔ͱ͍͏ͱ೉͍͕͠ɺ
    બ୒ࢶΛ஌ͬͨ͏͑ͰύλʔϯΛબͼ͍ͨ
    37
    

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38. ݁࿦
    ɾਓؒ͸ϛεΛ͠·͢
    ɾϛεΛ͢Δલʹɺ
    ද໌ΛίϯύΠϥ͕෼͔ΔܗͰॻ͚ͳ͍͔
    ҙࣝ͠ͳ͕Βઃܭ͠·͠ΐ͏
    38
    

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39. ͓·͚
    ͱͯ΋5෼Ͱ͸ޠΓ͖Εͳ͍࿩
    39
    

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40. ʮද໌ʯʹ͍ͭͯͷิ଍
    • Ҿ਺ɾ໭Γ஋ͷܕ͚͕ͩද໌Ͱ͸ͳ͍ͱݴ͚ͬͨΕͲ…
    • assert ͚ͩͰͳ͘ɺSwiftͰݴ͑͹ generics ΍ conditional conformance΋ද໌ͷํ๏
    • ΂ͭʹɺίϯύΠϥղऍෆೳͳද໌͸ྑ͘ͳ͍…Θ͚Ͱ͸ͳ͍
    • දݱྗΛ্͛Δͱֶशίετɾෳࡶੑ͕ϖΠ͠ͳ͍͜ͱ΋ଟ͍ͷͰɺͦ͜͸όϥϯε
    • ͨͱ͑͹ɺڽͬͨprotocolͷwhere۟ɺৗਓʹཧղग़དྷΔ͔ͬͯݴΘΕΔͱݫ͍͠ΑͶ…
    ɹ
    40
    

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41. ิ଍ͷิ଍
    ٯʹݴ͑͹ɺ
    ܖ໿ʹΑΔઃܭ͸
    ݴޠΛ໰Θͣద༻Մೳͳ֓೦Ͱ͢
    t_wada͞ΜʹΑΔ
    ͋͑ͯPHPΛϕʔεʹͨ͠εϥΠυ
    PHPer͡Όͳͯ͘΋ΦεεϝͰ͢
    https://speakerdeck.com/twada/php-
    conference-2016
    41
    

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42. ʮܧଓ౉͠ʯʹ͍ͭͯͷิ଍
    • ࣮͸ async/await͸ʮ಺෦తͳCPSม׵ʯͦͷ΋ͷͱ͍͑·͢
    Continuation Passing Style Revisited
    – Fabulous Adventures In Coding
    https://blogs.msdn.microsoft.com/ericlippert/2010/10/21/
    continuation-passing-style-revisited-part-one/
    ͦͷ࿨༁
    matarillo.com: ܧଓ౉͠ελΠϧ(CPS)ͱඇಉظߏจ(async/await)
    https://matarillo.com/general/cps
    42
    

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43. Swiftͷ async/await ͱ
    ܧଓͱ Future ͷؔ܎
    Chris Lattnerͷproposal2ʹΑΔͱɺ
    • ଞͷݴޠͰ͸ Future ͕·ͣ͋ͬͯɺͦͷ্ʹasync/await͕৐͔͍ͬͬͯΔ
    • Swiftͷasync/awaitͷઃܭͰ͸ͦΕΛલఏͱ͸ͤͣɺܧଓΛͦͷ··ѻ͏खஈΛ࿐ग़͍ͤͯ͞
    Δ
    • ͱ͸͍͑ Future ͱ͍͏ܕ෇͚͞Εͨঢ়ଶͰѻ͏ΠϯλϑΣʔε΋ߏஙՄೳͰ͢Αɺͱ͍͏͜ͱ
    2 https://gist.github.com/lattner/429b9070918248274f25b714dcfc7619
    yimajo͞Μͷʮasync/awaitݚڀಡຊʯ΋͋ΘͤͯͲ͏ͧ
    43
    

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44. ؔ࿈ɿʮܖ໿ʹΑΔઃ
    ܭʯΛΩʔϫʔυͰ֦
    ு͢Δ࿩
    ʮܖ໿ʹΑΔઃܭʯʹ͍ͭͯৄղ͞Ε
    ͍ͯΔʮΦϒδΣΫτࢦ޲ೖ໳ʯʹ
    ͸ɺ
    ඇಉظʢฒߦʣॲཧΛ΋ͱʹ֦ுͨ͠
    ৔߹ͷܖ໿ͷϙϦγʔʹ͍ͭͯͷٞ࿦
    ΋͋Γ·͢
    ໘ന͍Αʂ
    44
    

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