構造的差分ライブラリ開発時の悲劇・喜劇

https://iosdc-reject-conference.connpass.com/event/64175/

Transcript

1. ߏ଄తࠩ෼ϥΠϒϥϦ

   ։ൃ࣌ͷ൵ܶتܶ
   σόοάΛॿ͚Δ
   

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2. ߏ଄తͳࠩ෼ͱ͸Կ͔
   ·ͣ͸
   

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3. func testExample1() {
   let a = Example(
   key1: "I'm not changed",
   key2: "I'm deleted"
   )
   let b = Example(
   key1: "I'm not changed",
   key2: "I'm inserted"
   )
   XCTAssertEqual(a, b)
   }
   Α͋͘ΔTUSVDUͷൺֱ
   

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4. XCTAssertEqual failed: ("Example(key1: "I\'m not
   changed", key2: "I\'m deleted")") is not equal to
   ("Example(key1: "I\'m not changed", key2: "I\'m
   inserted")") -
   ςετ݁Ռ͸ඇৗʹΘ͔ΓͮΒ͍
   

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5. IUUQHJUIVCDPN,VOJXBL.JSSPS%J⒎,JU
   ͦ͜Ͱ
   

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6. import MirrorDiffKit
   func testExample2() {
   let a = Example(
   key1: "I'm not changed",
   key2: "I'm deleted"
   )
   let b = Example(
   key1: "I'm not changed",
   key2: "I'm inserted"
   )
   XCTAssertEqual(a, b, diff(between: a, and: b))
   }
   ࣦഊ࣌ͷϝοηʔδʹ

   .JSSPS%J⒎,JUͷEJ⒎Λࢦఆ
   .JSSPS%J⒎,JUΛJNQPSU
   

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7. struct Example {
   key1: "I'm not changed"
   - key2: "I'm deleted"
   + key2: "I'm inserted"
   }
   ͜Ε͕ߏ଄తͳࠩ෼
   ͙͢ʹࠩҟ͕Θ͔Γ·͢
   

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8. [
   "I'm not changed"
   "I'm not changed"
   - "I'm deleted"
   "I'm not changed"
   + "I'm inserted"
   ]
   ഑ྻͷॱংมߋͳͲ΋

   ߏ଄తͳࠩ෼Ͱ͢
   ͜Ε΋ݟ΍͘͢දࣔ͞Ε·͢
   

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9. IUUQHJUIVCDPN,VOJXBL.JSSPS%J⒎,JU
   ΑΖ͓͘͠ئ͍͠·͢
   

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10. ࢓૊Έͷղઆ
    ࠩ෼ܭࢉͷ
    

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11. let example = Example(
    key1: "I'm not changed",
    key2: "I'm deleted"
    )
    let hint = (
    subject: Example.self,
    displayStyle: .struct,
    children: [
    (label: "key1", value: "I'm not changed"),
    (label: "key2", value: "I'm deleted"),
    ]
    )
    ߏ଄తͳࠩ෼ͷܭࢉʹ͸ɺ

    ࣍ͷΑ͏ͳΦϒδΣΫτͷ

    ߏ଄ͷώϯτ͕ෆՄܽͰ͢
    ΦϒδΣΫτͷܕ
    ΦϒδΣΫτͷछྨ
    ϓϩύςΟͷ໊લͱ஋
    

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12. ͦͷػೳΛ୲͏ͷ͕.JSSPS

    ʢඪ४ϥΠϒϥϦͷ"1*Ͱ͢ʣ
    

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13. let example = Example(
    key1: "I'm not changed",
    key2: "I'm deleted"
    )
    let mirror = Mirror(reflecting: example)
    let hint = (
    subject: mirror.subjectType,
    displayStyle: mirror.displayStyle,
    children: mirror.children
    )
    ௐ΂͍ͨΦϒδΣΫτ͔Β

    .JSSPSΦϒδΣΫτΛ

    ࡞੒͢Δͱɺ
    ܕ৘ใ΍ΦϒδΣΫτͷछྨɺ

    ϓϩύςΟͷ໊લͱ஋ͳͲΛ

    ೖखͰ͖·͢
    

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14. .JSSPS%J⒎,JU͸ɺ

    ͜ͷ.JSSPSΛ࢖ͬͯ

    ࣮ݱ͞Ε͍ͯ·͢
    

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15. ͍ΖΜͳ͜ͱ͕Ͱ͖ͦ͏Ͱ

    ເͷ޿͕Δ"1*Ͱ͢Ͷ
    

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16. تܶ͸͜͜·Ͱͩ
    

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17. ΍͹͍OJM͕΍͹͍໰୊
    ൵ܶͦͷ
    

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18. struct Example {
    let any: Any?
    }
    let example = Example(any: nil)
    if let first = Mirror(reflecting: example)
    .children.first {
    print(first.value)
    }
    ϓϩύςΟΛOJMͰॳظԽ
    ϓϩύςΟͷ஋ΛݟΔͱɺ

    ઌ΄ͲOJMͰॳظԽͨ͠ͷͰ

    OJMʹͳ͍ͬͯΔ
    "OZ ͷϓϩύςΟ͕͋ΔTUSVDU
    .JSSPSΛ࡞੒ͯ͠ɺTUSVDUͷ

    ϓϩύςΟͷώϯτΛೖख
    

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19. struct Example {
    let any: Any?
    }
    let example = Example(any: nil)
    if let first = Mirror(reflecting: example)
    .children.first {
    print(first.value == nil)
    print(first.value)
    }
    GBMTF
    OJMͰ΋͔֬ΊͯΈΑ͏
    
    ͔͠͠ೖ͍ͬͯΔͷ͸OJMʜ
    

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20. ߟ࡯ฤ
    ൵͠Έͷ
    

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21. "OZʹ͸

    ͳΜͰ΋ೖΔ
    ᶃ
    Int
    String
    Bool
    Any
    
    
    

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22. 0QUJPOBM΋

    ೖΕΒΕΔ
    ᶄ
    Optional
    Any
    
    
    

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23. ͢ΔͱOJM΋

    ೖΓ͏Δ
    ᶄ
    nil
    Any
    
    
    

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24. 
    ᶄ
    nil
    Any
    
    
    == nil
    GBMTF
    

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25. let x: Any? = nil
    let wrapper: Any = x
    // WARNING: Comparing non-optional value of
    // type 'Any' to nil always returns false
    print(x == nil)
    ࣮͸ղઆͨ͠ྫΛίʔυʹ͢Δͱܯࠂ͕ग़Δ
    ʮ0QUJPOBM͡Όͳ͍஋ͱOJMΛ

    ɹൺֱͯ͠΋ৗʹGBMTFͩΑʯ
    
    

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26. ͭ·Γɺ"OZʹOJMΛ

    ೖΕͯ͸ͳΒͳ͍ͷͰ͢
    

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27. ͔͠͠ɺ.JSSPSͰऔಘͨ͠

    ϓϩύςΟͷ஋ͷܕ͸

    ໰౴ແ༻Ͱ"OZͱ͍͏൵͠Έ
    ͳͷͰɺϓϩύςΟʹOJMΛ΋ͭ

    ΦϒδΣΫτΛ.JSSPSʹ͔͚Δͱ

    Ϋϥογϡͷةݥ͕͋Γ·͢
    

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28. .JSSPS%J⒎,JUͰ͸͜ͷ໰୊ʹ

    ରॲ͍ͯ͠·͢ͷͰ҆͝৺Λʜ
    

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29. ཁૉ਺ͷUVQMF໰୊
    ൵ܶͦͷ
    

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30. enum Example {
    case zero
    case one(key: String)
    case two(key1: String, key2: String)
    }
    4XJGUͰ͸FOVNͷDBTFʹ෇ଐ͢Δ஋ΛఆٛͰ͖·͢
    ͜ͷ෇ଐ͢Δ஋͸BTTPDJBUFEWBMVFTͱݺ͹Ε͍ͯ·͢
    

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31. enum Example {
    case one(key: String)
    case two(key1: String, key2: String)
    }
    func test() {
    let x1: Example = .one(key: "value")
    let x2: Example = .two(key1: "value1", key2: "value2")
    let mirror1 = Mirror(reflecting: x1)
    let mirror2 = Mirror(reflecting: x2)
    dump(mirror1.children.first!.value)
    dump(mirror2.children.first!.value)
    }
    ͦΕͧΕΛ.JSSPSʹ͔͚·͢
    ͜͜Ͱ͸BTTPDJBUFEWBMVFTͷ

    ཁૉ਺͕ҟͳΔͭͷDBTFΛ

    ఆٛ͠·͢
    BTTPDJBUFWBMVFT͸ɺ

    TUSVDUͷϓϩύςΟͱ

    ಉ͡Α͏ʹDIJMESFOͰ

    දݱ͞Ε·͢
    ͦΕͧΕͷDIJMESFOΛ

    ֬ೝͯ͠Έ·͠ΐ͏
    

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32. enum Example {
    case one(key: String)
    case two(key1: String, key2: String)
    }
    func test() {
    let x1: Example = .one(key: "value")
    let x2: Example = .two(key1: "value1", key2: "value2")
    let mirror1 = Mirror(reflecting: x1)
    let mirror2 = Mirror(reflecting: x2)
    dump(mirror1.children.first!.value)
    dump(mirror2.children.first!.value)
    }
    BTTPDJBUFEWBMVFT͕

    ͭͷ৔߹
    WBMVF
    ͭͷ৔߹

    

    LFZWBMVF 

    LFZWBMVF

    
    
    ܕ͕ҧ͏
    
    

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33. ߟ࡯ฤ
    ൵͠Έͷ
    

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34. let y: Any = (number: 123)
    print(type(of: y))
    ܕΛௐ΂ͯΈΔͱ

    
    *OU
    ຊ౰͸BTTPDJBUFEWBMVFTͷཁૉ਺͕

    ͍ͭ͘Ͱ͋ΕɺDIJMESFOͷܕ͸UVQMFʹ

    ͔ͨͬͨ͠ͷͰ͸ͱਪଌ
    ͔͠͠ɺཁૉ਺ͷ͚࣌ͩࣄ৘͕͋ͬͯ

    UVQMFʹͰ͖ͳ͔͔ͬͨ΋͠Εͳ͍ͷͰɺ

    ࢼ͠ʹཁૉ͕ͭͷUVQMFΛ࡞੒ͯ͠ΈΔ
    UVQMFͰ͸ͳ͍
    
    

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35. // Error: cannot create a single-element tuple with
    // an element label
    let x: (number: Int) = (number: 123)

    

    let y: Any = (number: 123)
    print(type(of: y)) // Int
    ࣮͸ɺ4XJGUͷܕͰ͸ཁૉ͕ͭͷUVQMF͸ఆٛͰ͖ͳ͍
    ͔͠͠ɺཁૉ਺ͷUVQMFܕ͕

    ࡞Εͳ͍͚ͩͳͷͰɺܕΛ

    "OZʹͯ͠͠·͑͹ཁૉ਺ͷ

    UVQMFΒ͖͠΋ͷΛఆٛͰ͖Δ
    ͔͠͠ɺఆٛͰ͖ͨͱͯ͠΋ɺ

    ͦͷܕ͸ཁૉͷத਎ͷܕʹ

    ͳΔΑ͏ͩ
    ͭ·Γɺཁૉ਺ͷUVQMF͸

    ଘࡏͰ͖ͳ͍͜ͱ͕Θ͔Δ
    

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36. ཁૉ਺ͷUVQMFܕ͸ଘࡏͰ͖ͳ͍ͷͰɺ

    ຊདྷ͸UVQMFͰ͋Δ͸ͣͷ

    BTTPDJBUFEWBMVFT͕ɺཁૉ਺ͷ

    ͱ͖ʹத਎͚ͩʹͳΔͷͰͨ͠ʜ
    

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37. .JSSPS%J⒎,JUͰ͸͜ͷ໰୊ʹ

    ରॲ͍ͯ͠·͢ͷͰ҆͝৺Λʜ
    

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38. ΧδϡΞϧʹյΕΔ
    ൵ܶͦͷ
    

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39. ·ͱΊ
    w .JSSPSͱ͍͏TUSVDUͳͲͷߏ଄Λ

    ௐ΂ΔͨΊͷ"1*͕͋Γ·͢
    w ৭ʑͰ͖ͦ͏Ͱເ͕޿͕Γ·͢
    w ͔͠͠ɺ͔ͳΓͷͭΒΈ͕͋Γ·͢ͷͰ

    ΍͍ͬͯ͘ࡍʹ͸.JSSPS%J⒎,JUͷ

    ճආྫΛࢀߟʹ͢ΔͱΑ͍Ͱ͠ΐ͏
    

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