読みやすいコードの書き方 第 2 回 / Code readability: Session 2 (ver. 2, Ja)

第 2 回: 命名

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セッションリスト

第 1 回: 導入と原則
- https://speakerdeck.com/munetoshi/code-readability-session-1-ver-2-ja

第 2 回: 命名
- https://speakerdeck.com/munetoshi/code-readability-session-2-ver-2-ja

第 3 回: コメント
- https://speakerdeck.com/munetoshi/code-readability-session-3-ver-2-ja

第 4 回: 状態
- https://speakerdeck.com/munetoshi/code-readability-session-4-ver-2-ja

第 5 回: 関数
- https://speakerdeck.com/munetoshi/code-readability-session-5-ver-2-ja

第 6 回: 依存関係 I
- https://speakerdeck.com/munetoshi/code-readability-session-6-ver-2-ja

第 7 回: 依存関係 II
- https://speakerdeck.com/munetoshi/code-readability-session-7-ver-2-ja

第 8 回: レビュー
- https://speakerdeck.com/munetoshi/code-readability-session-8-ver-2-ja

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関連書籍 「読みやすいコードのガイドライン - 持続可能なソフトウェア開発のために」
- https://gihyo.jp/book/2022/978-4-297-13036-7

英語版のリスト: https://gist.github.com/munetoshi/65a1b563fb2c271f328c121a4ac63571#file-code-readability-links-md

以前のバージョン (英語): https://speakerdeck.com/munetoshi/code-readability

© 2019-2023 Munetoshi Ishikawa, supported by LINE corporation

Transcript

1. ಡΈ΍͍͢-ίʔυͷ-ॻ͖ํ ୈ-2-ճ
   ໋_໊
   

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2. લճͷ͓͞Β͍: ಋೖͱݪଇ
   ಡΈ΍͍͢ίʔυ: ੜ࢈ੑΛҡ࣋͢Δखஈ
   ϘʔΠεΧ΢τϧʔϧ: ίʔυมߋલΑΓಡΈ΍͘͢
   YAGNI: ඞཁʹͳͬͨͱ͖ʹॳΊ࣮ͯ૷
   KISS: ୯७ͳํ๏Λ࢖͏, ඒ͍͠ != ಡΈ΍͍͢
   ୯Ұ੹೚ݪଇ: ੹೚ൣғΛ໌֬ʹ
   ࣌ظঘૣͳ࠷దԽ: ࠷దԽͷલʹϓϩϑΝΠϦϯάɾݟੵ΋Γ
   

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3. ߨٛͷߏ੒
   - ಋೖͱݪଇ
   - ࣗવݴޠ: ໋໊, ίϝϯτ
   - ܕͷߏ଄: ঢ়ଶ, ؔ਺
   - ܕؒͷߏ଄: ґଘؔ܎I, ґଘؔ܎II
   - ϨϏϡʔ
   ໋໊ > ಋೖ
   

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4. ໋໊ͷର৅
   - Ϋϥε, ΠϯλʔϑΣΠε, ྻڍܕ, ߏ଄ମ, ϓϩτίϧ, τϨΠτ
   - ม਺, ϓϩύςΟ, ϑΟʔϧυ, ύϥϝʔλ, ఆ਺
   - ؔ਺, ϝιου, खଓ͖, αϒϧʔνϯ
   - είʔϓ, ύοέʔδ, Ϟδϡʔϧ, ໊લۭؒ
   - Ϧιʔε, ϑΝΠϧ, σΟϨΫτϦ, ID
   - etc.
   ໋໊ > ಋೖ
   

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5. Α໊͍લͱ͸
   ਖ਼֬
   - isVisible ΛʮԻʯʹ࢖ͬͯ͸͍͚ͳ͍
   આ໌త
   - w / h ΑΓ΋ width / height
   - image ΑΓ΋ imageView / imageBitmap / imageUrl
   ໋໊ > ಋೖ
   

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6. Α໋໊͍Λ͢Δʹ͸
   - ਖ਼͍͠จ๏Λ࢖͏
   - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
   - ҙຯͷڱ͍ޠΛબͿ
   - ࠞཚΛটུ͘ޠΛආ͚Δ
   - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
   - ߠఆతͳදݱΛ࢖͏
   ໋໊ > ಋೖ
   

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7. ࠓճͷ಺༰
   - ਖ਼͍͠จ๏Λ࢖͏
   - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
   - ҙຯͷڱ͍ޠΛબͿ
   - ࠞཚΛটུ͘ޠΛආ͚Δ
   - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
   - ߠఆతͳදݱΛ࢖͏
   ໋໊ > ಋೖ
   

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8. จ๏͕ॏཁͳཧ༝
   ໰୊ 1: CallbackEventMessageClickViewText ͸ԿΛҙຯ͢Δʁ
   ղ౴ 1ʁ: A text of a click view (?) of callback event message (???)
   ໰୊ 2: MessageTextViewClickEventCallback ͸ԿΛҙຯ͢Δʁ
   ղ౴ 2: A callback of click events on a message text view
   ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
   

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9. ਖ਼͍͠จ๏Λ࢖͏
   ʮจ๏ʯ͸ϓϩάϥϛϯάݴޠ΍ن໿ʹґଘ͢Δ
   Java / Kotlin ͷྫΛ঺հ
   ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
   

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10. ໊લͷछྨ 1/2
    - ໊ࢺ: Ϋϥεɾม਺ɾঢ়ଶ΍ଐੑΛࣔؔ͢਺
    imageView, HashSet, indexOf
    - ໋ྩܗ: ؔ਺
    findMessage, compareTo
    ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
    

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11. ໊લͷछྨ 2/2
    - ܗ༰ࢺɾ෼ࢺ: ΠϯλʔϑΣΠεɾঢ়ଶΛࣔ͢ܕ΍஋
    Iterable
    ,
    PLAYING
    ,
    CONNECTED
    - ٙ໰ܗɾࡾਓশͷ(ॿ)ಈࢺ: ਅِ஋ɾਅِ஋Λฦؔ͢਺
    isTextVisible
    ,
    contains
    ,
    equalsTo
    ,
    may
    /
    shouldShow
    - લஔࢺΛ࣋ͭ෭ࢺ: ܕม׵Λ͢Δؔ਺, ίʔϧόοΫؔ਺
    toInt
    ,
    fromMemberId
    ,
    onClickEvent
    ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
    

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12. จ๏: ໊ࢺ
    ॏཁͳ୯ޠΛ࠷ޙʹஔ͘
    (= ࠷ޙͷ୯ޠͰͦΕ͕ԿͰ͋Δ͔ɾԿΛ͢Δ͔Λࣔ͢)
    !
    :
    MessageEventHandler
    ,
    buttonHeight
    !
    :
    xyzHeightForPortrait
    (Ϋϥε໊ͱͯ͠͸ෆద)
    !
    :
    HandlerMessageEvent
    (ϋϯυϥͷ৔߹),
    heightPortrait
    ྫ֎: ʮঢ়ଶ΍ଐੑΛࣔؔ͢਺໊ʯ͸લஔࢺͰऴΘΔ৔߹͕͋Δ
    e.g.,
    indexOf(value)
    ,
    maxValueIn(array)
    ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
    

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13. จ๏: ໋ྩܗ
    ಈࢺΛ࠷ॳʹஔ͘
    "X Λऔಘ͢Δ":
    !
    getX,
    "
    xGet
    "Y Λ౤ߘ͢Δ":
    !
    postY,
    "
    yPost
    "Z ʹରԠͤ͞Δ":
    !
    mapToZ,
    "
    toZMap, zToMap
    ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
    

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14. ؒҧͬͨޠॱ͕࢖ΘΕΔཧ༝
    class UserActionEvent
    class UserActionEventSwipe: UserActionEvent()
    class UserActionEventClickMessageText: UserActionEvent()
    class UserActionEventClickProfileImage: UserActionEvent()
    mutableListOf()
    ίʔυΛʮ࢖͏ଆʯͰͲ͏ݟ͑Δ͔͕ॏཁ
    ݟͨ໨ͷ౷Ұײ ͷΈʹয఺Λ౰ͯͯ͸ͳΒͳ͍
    ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
    

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15. จ๏: ·ͱΊ
    - ໊લͷछྨ
    ໊ࢺɾ໋ྩܗɾܗ༰ࢺɾٙ໰จ(+ࡾਓশ)ɾ෭ࢺ
    - ޠॱͷॏཁੑ
    ίʔυΛʮ࢖͏ଆʯͰͲ͏ݟ͑Δ͔
    ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
    

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16. ࠓճͷ಺༰
    - ਖ਼͍͠จ๏Λ࢖͏
    - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    - ҙຯͷڱ͍ޠΛબͿ
    - ࠞཚΛটུ͘ޠΛආ͚Δ
    - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    - ߠఆతͳදݱΛ࢖͏
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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17. ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    දݱ͢Δ΂͖಺༰
    !
    ͦͷม਺΍Ϋϥε͕ Կ Ͱ͋Δ͔
    !
    ͦͷؔ਺͕ Կ Λ͢Δ͔
    ݴٴ͢Δ΂͖Ͱͳ͍಺༰
    !
    ͦͷίʔυΛ ͩΕ ͕࢖͏͔
    !
    ͦͷίʔυ͕ ͍ͭɾͲ͜ͰɾͳͥɾͲͷΑ͏ʹ ࢖ΘΕΔ͔
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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18. ؔ਺໊ͷྫ: એݴଆ
    !
    ͦͷؔ਺͕ Կ Λ͢Δ͔Λදݱ͢Δ
    class MessageRepository {
    fun storeReceivedMessage(data: MessageData) {
    !
    ͦͷؔ਺͕ ͍ͭ ݺ͹ΕΔ͔Λදݱ͢Δ
    class MessageRepository {
    fun onMessageReceived(data: MessageData) {
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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19. ؔ਺໊ͷྫ: ݺͼग़͠ଆ
    !
    ݺͼग़͠ଆͷίʔυͰ Կ͕ى͖Δ͔͕Θ͔Δ
    repository.storeReceivedMessage(messageData)
    presenter.showNewReceivedMessage(messageData)
    !
    ݺͼग़͠ଆͷίʔυͰ Կ͕ى͖Δ͔͕Θ͔Βͳ͍
    repository.onMessageReceived(messageData)
    presenter.onMessageReceived(messageData)
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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20. ؔ਺໊ͷྫ: ʮ͍ͭʯ͕Α͘ͳ͍ผͷཧ༝
    ؔ਺ͷ੹೚͕ᐆດʹͳΔ
    class MessageViewPresenter {
    fun onMessageReceived(data: MessageData) {
    // View presentation code for new message ...
    repository.onMessageReceived(data) // !!
    ॏෳݺͼग़͠ͷόάͷݪҼʹͳΔ͜ͱ΋
    repository.onMessageReceived(messageData)
    presenter.onMessageReceived(messageData)
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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21. Ҿ਺໊ͷྫ: એݴଆ
    !
    true ͷͱ͖ Կ͕ى͜Δ͔͕Θ͔Δ
    fun showHistory(shouldShowDialogOnError: Boolean)
    !
    true ͷͱ͖ Կ͕ى͜Δ͔Θ͔Βͳ͍
    fun showHistory(isCalledAtMainScreen: Boolean)
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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22. Ҿ਺໊ͷྫ: ʮͩΕʯ͕Α͘ͳ͍ཧ༝
    1: ໊લ͕ ࠷৽ͷঢ়گ ͱҰக͠ͳ͘ͳΔ
    // ... from another screen requiring dialog
    showHistory(isCalledAtMainScreen = true)
    2: Ҿ਺͕ ଞͷ໨త ͷͨΊʹ࢖ΘΕΔ
    if (isCalledAtMainScreen) { setScreenTitle("Main") ...
    1 ͱ 2 ͕ಉ࣌ʹى͜Δͱ όά͕ൃੜ͢Δ
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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23. ʮԿʯΛઆ໌͢Δ: ྫ֎
    ʮԿʯΛ͢Δ͔͕ܾ·͍ͬͯͳ͍ ந৅ίʔϧόοΫؔ਺
    ྫ: onClicked, onSwiped, onDestroyedɹ
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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24. ʮԿʯΛઆ໌͢Δ: ྫ֎
    ʮԿʯΛ͢Δ͔͕ܾ·͍ͬͯͳ͍ ந৅ίʔϧόοΫؔ਺
    ྫ: onClicked, onSwiped, onDestroyedɹ
    ʮ͍ͭɾͲͷΑ͏ʹʯͰ໋໊͔͠Ͱ͖ͳ͍
    ίʔϧόοΫͰ΋ʮԿʯΛ͢Δ͔͕ܾ·͍ͬͯΔ৔߹ʹ஫ҙ
    abstract fun toggleSelectionState()
    ...
    view.setClickCallback { toggleSelectionState() }
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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25. ʮԿʯΛઆ໌͢Δ: ·ͱΊ
    ͦΕ͕ʮԿʯͰ͋Δ͔ɾʮԿʯΛ͢Δ͔Λઆ໌͢Δ
    =ʮͩΕɾ͍ͭɾͲ͜ͰɾͳͥɾͲͷΑ͏ʹʯʹ͸ݴٴ͠ͳ͍
    - ੹೚Λ໌ࣔ͢Δ
    - ʮ࢖͏ଆʯͷίʔυΛಡΈ΍͘͢͢Δ
    ྫ֎: ԿΛ͢Δ͔͕ܾ·͍ͬͯͳ͍ந৅ίʔϧόοΫؔ਺
    ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    

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26. ࠓճͷ಺༰
    - ਖ਼͍͠จ๏Λ࢖͏
    - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    - ҙຯͷڱ͍ޠΛબͿ
    - ࠞཚΛটུ͘ޠΛආ͚Δ
    - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    - ߠఆతͳදݱΛ࢖͏
    ໋໊ > ҙຯͷڱ͍ޠΛબͿ
    

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27. ୯ޠͷҙຯͷ޿͞: ྫ 1/2
    ໰୊: initializationFlag ͸ԿΛҙຯ͢Δʁ
    - shouldInitialize
    - isInitializing
    - is/wasInitialized
    - isInitializable
    - isNotInitialized (!!)
    ʢ࠷ޙҎ֎ͷʣ্هͷͲΕ͔Ͱஔ͖׵͑Δ
    ໋໊ > ҙຯͷڱ͍ޠΛબͿ
    

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28. ୯ޠͷҙຯͷ޿͞: ྫ 2/2
    ໰୊: sizeLimit ͸ԿΛҙຯ͢Δʁ
    - max, minʁ
    - height, width, byte, characters, lengthʁ
    maxHeight ౳ͱ໋໊͢Δ
    ໋໊ > ҙຯͷڱ͍ޠΛબͿ
    

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29. ஔ͖׵͑Δ΂͖୯ޠͷྫ
    - flag: is, was, should, can, may, will ...
    - check: is, query, verify, measure, filter, notify, update ...
    - good, fine: valid, completed, reliable, secure, satisfies ...
    - old: previous, stored, expired, invalidated, deprecated ...
    - tmp, retval: ࣮ࡍͷ໊લ
    ࣙॻ΍ྨޠࣙయΛ࢖͏
    ໋໊ > ҙຯͷڱ͍ޠΛબͿ
    

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30. ҙຯͷڱ͍ޠΛબͿ: ·ͱΊ
    - flag ΍ check ౳ͷ ҙຯͷ޿͍୯ޠ Λஔ͖׵͑Δ
    - ࣙॻ ΍ ྨޠࣙయ Λ࢖͏
    ໋໊ > ҙຯͷڱ͍ޠΛબͿ
    

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31. ࠓճͷ಺༰
    - ਖ਼͍͠จ๏Λ࢖͏
    - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    - ҙຯͷڱ͍ޠΛબͿ
    - ࠞཚΛটུ͘ޠΛආ͚Δ
    - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    - ߠఆతͳදݱΛ࢖͏
    ໋໊ > ࠞཚΛটུ͘ޠΛආ͚Δ
    

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32. ུޠ: ྫ 1/2
    ໰୊: im ͱ͍͏໊લ͸ԿΛҙຯ͢Δʁ
    input method, illegal message, instance manager ...
    ಠࣗͷུޠΛආ͚Δ
    ʮೝࣝʯ͸ʮ૝ىʯΑΓ΋؆୯3
    3 100 Things: Every Designer Needs to Know About People, Susan Weinschenk, 2011
    ໋໊ > ࠞཚΛটུ͘ޠΛආ͚Δ
    

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33. ུޠ: ྫ 2/2
    ໰୊: str ͱ͍͏໊લ͸ԿΛҙຯ͢Δ?
    string, structure, stream, streak, street, sorted transaction record
    Ұൠతͳུޠ͸ڐ༰Ͱ͖Δ͜ͱ΋
    - URL ΍ TCP ౳ͷ࢖༻͸໰୊ͳ͍
    - string Λҙຯ͢Δ str ͸ ݶΒΕͨείʔϓ ͳΒڐ༰͞ΕΔ͔΋
    ໋໊ > ࠞཚΛটུ͘ޠΛආ͚Δ
    

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34. ϓϩμΫτݻ༗ͷུޠ
    ϓϩμΫτݻ༗ͷུޠ͕࢖ΘΕΔ͜ͱ͕͋Δ
    νʔϜͷ৽نϝϯόʔ͕ཧղͰ͖ΔΑ͏ʹ͢Δ
    - Ϋϥεɾؔ਺ɾม਺ͷυΩϡϝϯςʔγϣϯΛॻ͘
    - ༻ޠूΛผ్༻ҙ͓ͯ͘͠
    ໋໊ > ࠞཚΛটུ͘ޠΛආ͚Δ
    

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35. ࠞཚΛটུ͘ޠΛආ͚Δ: ·ͱΊ
    - ಠࣗͷུޠ: ࢖Θͳ͍
    - Ұൠతͳུޠ: ڐ༰͞ΕΔ͜ͱ͕͋Δ
    - ϓϩμΫτݻ༗ͷུޠ: υΩϡϝϯςʔγϣϯɾ༻ޠूͰઆ໌
    ໋໊ > ࠞཚΛটུ͘ޠΛආ͚Δ
    

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36. ࠓճͷ಺༰
    - ਖ਼͍͠จ๏Λ࢖͏
    - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    - ҙຯͷڱ͍ޠΛબͿ
    - ࠞཚΛটུ͘ޠΛආ͚Δ
    - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    - ߠఆతͳදݱΛ࢖͏
    ໋໊ > ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    

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37. ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    ʮ੔਺ܕʯͰ͸୯Ґ΍࣮ମ͕ᐆດͳ͜ͱ͕͋Δ
    - timeout: timeoutInMillis, timeoutInSeconds
    - width: widthInPixels, widthInPoints, widthInInches
    - color: argbColorInt, colorResId
    - i, j, k: userIndex, row, col
    ໋໊ > ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    

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38. ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ: ༨ஊ
    ΫϥεͰ୯ҐΛදݱ͢Δ͜ͱ΋Մೳ
    class Inch(val value: Int)
    class Centimeter(val value: Int)
    fun setWidth(width: Inch) = ...
    setWidth(Centimeter(10)) // Compile error!
    - Scala ͷ஋Ϋϥε΍ Kotlin ͷΠϯϥΠϯΫϥε౳΋༗ޮ
    - Kotlin ͷ Duration ͷΑ͏ʹ୯ҐΛಁաతʹѻ͏͜ͱ΋Ͱ͖Δ
    ໋໊ > ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    

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39. ࠓճͷ಺༰
    - ਖ਼͍͠จ๏Λ࢖͏
    - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    - ҙຯͷڱ͍ޠΛબͿ
    - ࠞཚΛটུ͘ޠΛආ͚Δ
    - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    - ߠఆతͳදݱΛ࢖͏
    ໋໊ > ߠఆతͳදݱΛ࢖͏
    

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40. ߠఆతͳදݱΛ࢖͏
    !
    : ߠఆతͳޠ, isEnabled
    !
    : ൱ఆతͳޠ, isDisabled
    !
    : ߠఆతͳޠ + notɾnoɾnon, isNotEnabled
    !
    : ൱ఆతͳޠ + notɾnoɾnon, isNotDisabled
    isNotDisabled → isEnabled isNotEnabled → isDisabled ͸
    ୯७ʹஔ׵Մೳ
    ໋໊ > ߠఆతͳදݱΛ࢖͏
    

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41. ࠓճͷ಺༰
    - ਖ਼͍͠จ๏Λ࢖͏
    - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
    - ҙຯͷڱ͍ޠΛબͿ
    - ࠞཚΛটུ͘ޠΛආ͚Δ
    - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
    - ߠఆతͳදݱΛ࢖͏
    ໋໊ > ݴޠɾϓϥοτϑΥʔϜɾϓϩμΫτͷن໿ʹै͏
    

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42. ࠓճͷ಺༰: ௥Ճ
    ݴޠɾϓϥοτϑΥʔϜɾϓϩμΫτͷن໿ʹै͏
    ໋໊ > ݴޠɾϓϥοτϑΥʔϜɾϓϩμΫτͷن໿ʹै͏
    

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43. ݴޠɾϓϥοτϑΥʔϜɾϓϩμΫτͷن໿ʹै͏
    ݴޠɾϓϥοτϑΥʔϜݻ༗ͷ ن໿ɾϧʔϧɾෆจ཯ ʹै͏
    - จ๏: itemCount vs. numItem
    - ུޠ: milliSeconds vs. millis vs. ms
    ඪ४ϥΠϒϥϦɾAPI Λࢀর͢Δ
    ෆ໌ͳ఺ʹ͍ͭͯ͸ϓϩμΫτͰن໿ΛఆΊΔ
    ໋໊ > ݴޠɾϓϥοτϑΥʔϜɾϓϩμΫτͷن໿ʹै͏
    

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44. ·ͱΊ
    ໊લ͸ਖ਼͔֬ͭઆ໌తʹ
    - ໊લͷࣔ͢಺༰: ʮ͍ͭɾͩΕʯΑΓʮԿʯ
    - จ๏: ॏཁͳ୯ޠͷҐஔ
    - ୯ޠ: ҙຯ͕ڱ͍ɾলུ͠ͳ͍ɾߠఆత
    ໋໊ > ·ͱΊ
    

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