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 ໋_໊
2. લճͷ͓͞Β͍: ಋೖͱݪଇ ಡΈ΍͍͢ίʔυ: ੜ࢈ੑΛҡ࣋͢Δखஈ ϘʔΠεΧ΢τϧʔϧ: ίʔυมߋલΑΓಡΈ΍͘͢ YAGNI: ඞཁʹͳͬͨͱ͖ʹॳΊ࣮ͯ૷ KISS: ୯७ͳํ๏Λ࢖͏, ඒ͍͠ != ಡΈ΍͍͢ ୯Ұ੹೚ݪଇ: ੹೚ൣғΛ໌֬ʹ ࣌ظঘૣͳ࠷దԽ: ࠷దԽͷલʹϓϩϑΝΠϦϯάɾݟੵ΋Γ
3. ߨٛͷߏ੒ - ಋೖͱݪଇ - ࣗવݴޠ: ໋໊, ίϝϯτ - ܕͷߏ଄: ঢ়ଶ, ؔ਺ - ܕؒͷߏ଄: ґଘؔ܎I, ґଘؔ܎II - ϨϏϡʔ ໋໊ > ಋೖ
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
5. Α໊͍લͱ͸ ਖ਼֬ - isVisible ΛʮԻʯʹ࢖ͬͯ͸͍͚ͳ͍ આ໌త - w / h ΑΓ΋ width / height - image ΑΓ΋ imageView / imageBitmap / imageUrl ໋໊ > ಋೖ
6. Α໋໊͍Λ͢Δʹ͸ - ਖ਼͍͠จ๏Λ࢖͏ - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ - ҙຯͷڱ͍ޠΛબͿ - ࠞཚΛটུ͘ޠΛආ͚Δ - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ - ߠఆతͳදݱΛ࢖͏ ໋໊ > ಋೖ
7. ࠓճͷ಺༰ - ਖ਼͍͠จ๏Λ࢖͏ - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ - ҙຯͷڱ͍ޠΛબͿ - ࠞཚΛটུ͘ޠΛආ͚Δ - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ - ߠఆతͳදݱΛ࢖͏ ໋໊ > ಋೖ
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࢖͏
9. ਖ਼͍͠จ๏Λ࢖͏ ʮจ๏ʯ͸ϓϩάϥϛϯάݴޠ΍ن໿ʹґଘ͢Δ Java / Kotlin ͷྫΛ঺հ ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
10. ໊લͷछྨ 1/2 - ໊ࢺ: Ϋϥεɾม਺ɾঢ়ଶ΍ଐੑΛࣔؔ͢਺ imageView, HashSet, indexOf - ໋ྩܗ: ؔ਺ findMessage, compareTo ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
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࢖͏
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࢖͏
13. จ๏: ໋ྩܗ ಈࢺΛ࠷ॳʹஔ͘ "X Λऔಘ͢Δ": ! getX, " xGet "Y Λ౤ߘ͢Δ": ! postY, " yPost "Z ʹରԠͤ͞Δ": ! mapToZ, " toZMap, zToMap ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
14. ؒҧͬͨޠॱ͕࢖ΘΕΔཧ༝ class UserActionEvent class UserActionEventSwipe: UserActionEvent() class UserActionEventClickMessageText: UserActionEvent() class UserActionEventClickProfileImage: UserActionEvent() mutableListOf<UserActionEventClickProfileImage>() ίʔυΛʮ࢖͏ଆʯͰͲ͏ݟ͑Δ͔͕ॏཁ ݟͨ໨ͷ౷Ұײ ͷΈʹয఺Λ౰ͯͯ͸ͳΒͳ͍ ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
15. จ๏: ·ͱΊ - ໊લͷछྨ ໊ࢺɾ໋ྩܗɾܗ༰ࢺɾٙ໰จ(+ࡾਓশ)ɾ෭ࢺ - ޠॱͷॏཁੑ ίʔυΛʮ࢖͏ଆʯͰͲ͏ݟ͑Δ͔ ໋໊ > ਖ਼͍͠จ๏Λ࢖͏
16. ࠓճͷ಺༰ - ਖ਼͍͠จ๏Λ࢖͏ - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ - ҙຯͷڱ͍ޠΛબͿ - ࠞཚΛটུ͘ޠΛආ͚Δ - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ - ߠఆతͳදݱΛ࢖͏ ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
17. ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ දݱ͢Δ΂͖಺༰ ! ͦͷม਺΍Ϋϥε͕ Կ Ͱ͋Δ͔ ! ͦͷؔ਺͕ Կ Λ͢Δ͔ ݴٴ͢Δ΂͖Ͱͳ͍಺༰ ! ͦͷίʔυΛ ͩΕ ͕࢖͏͔ ! ͦͷίʔυ͕ ͍ͭɾͲ͜ͰɾͳͥɾͲͷΑ͏ʹ ࢖ΘΕΔ͔ ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
18. ؔ਺໊ͷྫ: એݴଆ ! ͦͷؔ਺͕ Կ Λ͢Δ͔Λදݱ͢Δ class MessageRepository { fun storeReceivedMessage(data: MessageData) { ! ͦͷؔ਺͕ ͍ͭ ݺ͹ΕΔ͔Λදݱ͢Δ class MessageRepository { fun onMessageReceived(data: MessageData) { ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
19. ؔ਺໊ͷྫ: ݺͼग़͠ଆ ! ݺͼग़͠ଆͷίʔυͰ Կ͕ى͖Δ͔͕Θ͔Δ repository.storeReceivedMessage(messageData) presenter.showNewReceivedMessage(messageData) ! ݺͼग़͠ଆͷίʔυͰ Կ͕ى͖Δ͔͕Θ͔Βͳ͍ repository.onMessageReceived(messageData) presenter.onMessageReceived(messageData) ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
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
21. Ҿ਺໊ͷྫ: એݴଆ ! true ͷͱ͖ Կ͕ى͜Δ͔͕Θ͔Δ fun showHistory(shouldShowDialogOnError: Boolean) ! true ͷͱ͖ Կ͕ى͜Δ͔Θ͔Βͳ͍ fun showHistory(isCalledAtMainScreen: Boolean) ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
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
23. ʮԿʯΛઆ໌͢Δ: ྫ֎ ʮԿʯΛ͢Δ͔͕ܾ·͍ͬͯͳ͍ ந৅ίʔϧόοΫؔ਺ ྫ: onClicked, onSwiped, onDestroyedɹ ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
24. ʮԿʯΛઆ໌͢Δ: ྫ֎ ʮԿʯΛ͢Δ͔͕ܾ·͍ͬͯͳ͍ ந৅ίʔϧόοΫؔ਺ ྫ: onClicked, onSwiped, onDestroyedɹ ʮ͍ͭɾͲͷΑ͏ʹʯͰ໋໊͔͠Ͱ͖ͳ͍ ίʔϧόοΫͰ΋ʮԿʯΛ͢Δ͔͕ܾ·͍ͬͯΔ৔߹ʹ஫ҙ abstract fun toggleSelectionState() ... view.setClickCallback { toggleSelectionState() } ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
25. ʮԿʯΛઆ໌͢Δ: ·ͱΊ ͦΕ͕ʮԿʯͰ͋Δ͔ɾʮԿʯΛ͢Δ͔Λઆ໌͢Δ =ʮͩΕɾ͍ͭɾͲ͜ͰɾͳͥɾͲͷΑ͏ʹʯʹ͸ݴٴ͠ͳ͍ - ੹೚Λ໌ࣔ͢Δ - ʮ࢖͏ଆʯͷίʔυΛಡΈ΍͘͢͢Δ ྫ֎: ԿΛ͢Δ͔͕ܾ·͍ͬͯͳ͍ந৅ίʔϧόοΫؔ਺ ໋໊ > ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ
26. ࠓճͷ಺༰ - ਖ਼͍͠จ๏Λ࢖͏ - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ - ҙຯͷڱ͍ޠΛબͿ - ࠞཚΛটུ͘ޠΛආ͚Δ - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ - ߠఆతͳදݱΛ࢖͏ ໋໊ > ҙຯͷڱ͍ޠΛબͿ
27. ୯ޠͷҙຯͷ޿͞: ྫ 1/2 ໰୊: initializationFlag ͸ԿΛҙຯ͢Δʁ - shouldInitialize - isInitializing - is/wasInitialized - isInitializable - isNotInitialized (!!) ʢ࠷ޙҎ֎ͷʣ্هͷͲΕ͔Ͱஔ͖׵͑Δ ໋໊ > ҙຯͷڱ͍ޠΛબͿ
28. ୯ޠͷҙຯͷ޿͞: ྫ 2/2 ໰୊: sizeLimit ͸ԿΛҙຯ͢Δʁ - max, minʁ - height, width, byte, characters, lengthʁ maxHeight ౳ͱ໋໊͢Δ ໋໊ > ҙຯͷڱ͍ޠΛબͿ
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
30. ҙຯͷڱ͍ޠΛબͿ: ·ͱΊ - flag ΍ check ౳ͷ ҙຯͷ޿͍୯ޠ Λஔ͖׵͑Δ - ࣙॻ ΍ ྨޠࣙయ Λ࢖͏ ໋໊ > ҙຯͷڱ͍ޠΛબͿ
31. ࠓճͷ಺༰ - ਖ਼͍͠จ๏Λ࢖͏ - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ - ҙຯͷڱ͍ޠΛબͿ - ࠞཚΛটུ͘ޠΛආ͚Δ - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ - ߠఆతͳදݱΛ࢖͏ ໋໊ > ࠞཚΛটུ͘ޠΛආ͚Δ
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
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
34. ϓϩμΫτݻ༗ͷུޠ ϓϩμΫτݻ༗ͷུޠ͕࢖ΘΕΔ͜ͱ͕͋Δ νʔϜͷ৽نϝϯόʔ͕ཧղͰ͖ΔΑ͏ʹ͢Δ - Ϋϥεɾؔ਺ɾม਺ͷυΩϡϝϯςʔγϣϯΛॻ͘ - ༻ޠूΛผ్༻ҙ͓ͯ͘͠ ໋໊ > ࠞཚΛটུ͘ޠΛආ͚Δ
35. ࠞཚΛটུ͘ޠΛආ͚Δ: ·ͱΊ - ಠࣗͷུޠ: ࢖Θͳ͍ - Ұൠతͳུޠ: ڐ༰͞ΕΔ͜ͱ͕͋Δ - ϓϩμΫτݻ༗ͷུޠ: υΩϡϝϯςʔγϣϯɾ༻ޠूͰઆ໌ ໋໊ > ࠞཚΛটུ͘ޠΛආ͚Δ
36. ࠓճͷ಺༰ - ਖ਼͍͠จ๏Λ࢖͏ - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ - ҙຯͷڱ͍ޠΛબͿ - ࠞཚΛটུ͘ޠΛආ͚Δ - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ - ߠఆతͳදݱΛ࢖͏ ໋໊ > ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ
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
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
39. ࠓճͷ಺༰ - ਖ਼͍͠จ๏Λ࢖͏ - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ - ҙຯͷڱ͍ޠΛબͿ - ࠞཚΛটུ͘ޠΛආ͚Δ - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ - ߠఆతͳදݱΛ࢖͏ ໋໊ > ߠఆతͳදݱΛ࢖͏
40. ߠఆతͳදݱΛ࢖͏ ! : ߠఆతͳޠ, isEnabled ! : ൱ఆతͳޠ, isDisabled ! : ߠఆతͳޠ + notɾnoɾnon, isNotEnabled ! : ൱ఆతͳޠ + notɾnoɾnon, isNotDisabled isNotDisabled → isEnabled isNotEnabled → isDisabled ͸ ୯७ʹஔ׵Մೳ ໋໊ > ߠఆతͳදݱΛ࢖͏
41. ࠓճͷ಺༰ - ਖ਼͍͠จ๏Λ࢖͏ - ʮ͍ͭɾͩΕ͕ʯΑΓʮԿʯΛઆ໌͢Δ - ҙຯͷڱ͍ޠΛબͿ - ࠞཚΛটུ͘ޠΛආ͚Δ - ܕ΍୯ҐΛࣔ͢୯ޠΛՃ͑Δ - ߠఆతͳදݱΛ࢖͏ ໋໊ > ݴޠɾϓϥοτϑΥʔϜɾϓϩμΫτͷن໿ʹै͏
42. ࠓճͷ಺༰: ௥Ճ ݴޠɾϓϥοτϑΥʔϜɾϓϩμΫτͷن໿ʹै͏ ໋໊ > ݴޠɾϓϥοτϑΥʔϜɾϓϩμΫτͷن໿ʹै͏
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