KotlinにおけるFactoryメソッド実装パターン

Transcript

1. Kotlinʹ͓͚ΔFactoryϝιουͷ
   ࣮૷ύλʔϯ
   Server-Side Kotlin Study #2
   2021/09/22 খࢁ݈ଠ(Kenta Koyama) @doyaaaaaaken
   

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2. ࣗݾ঺հ
   • ࢓ࣄ
   • גࣜձࣾsmartround ૑ۀϝϯόʔ / CTO
   • αʔόαΠυKotlinʢKtorʣɾVueJSΛࠓ͸Α͘ॻ͍͍ͯ·͢
   • OSS׆ಈ
   • kotlin-csvͷ࡞ऀʢ⭐: 300overʣ
   • KtorɾExposedɾkotest౳΁ͷίϯτϦϏϡʔτ
   

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3. ࿩͢಺༰
   Kotlinʹ͓͚ΔFactoryϝιουͷ࣮૷ύλʔϯ
   ʹ͍ͭͯ঺հ
   ࢀߟɿEffective Kotlin
   ɹɹɹItem33: Consider factory functions instead of constructors
   

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4. ͜ͷൃද಺ʹ͓͚Δ”Factoryϝιου”ͷఆٛ
   ʰΠϯελϯεੜ੒Λߦ͏ͨΊͷϝιουʱͱ͍͏ఆٛͰଊ͍͑ͯͩ͘͞
   ※ GoFʹΑΔσβΠϯύλʔϯͷ”Factoryύλʔϯ”ͱ͸ҟͳΓ·͢
   ʰίϯετϥΫλͷ௚઀ݺͼग़͠ʹΑΔΠϯελϯεੜ੒ʱͰ͸ͳ͘
   ʰϝιουܦ༝ͰͷΠϯελϯεੜ੒ํ๏ʢʹFactoryϝιουʣʱΛ
   ࢖͏΂͖࣌ɾ࢖͍ํʹ͍ͭͯͷ঺հͰ͢
   

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5. ໨࣍
   1. ίϯετϥΫλΑΓFactoryϝιου͕༏Ε͍ͯΔ఺ 5ͭ
   2. KotlinͰͷFactoryϝιου࣮૷ͷॻ͖ํ 5ύλʔϯ
   

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6. ໨࣍
   1. ίϯετϥΫλΑΓFactoryϝιου͕༏Ε͍ͯΔ఺ 5ͭ
   2. KotlinͰͷFactoryϝιου࣮૷ͷॻ͖ํ 5ύλʔϯ
   

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7. ᶃ: ϝιουʹ໊લ͕͚ͭΒΕΔ
   

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8. ᶄ: ฦΓ஋ΛαϒλΠϓʹͰ͖Δ
   

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9. ᶅ: ඞͣ͠΋Πϯελϯεੜ੒͠ͳͯ͘ྑ͍
   

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10. ᶆ: ՄࢹੑΛॊೈʹ੍ޚͰ͖Δ
    

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11. ᶇ: Ҿ਺Λ޷͖ʹఆٛͰ͖Δ
    

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12. ͜͜·Ͱͷ·ͱΊ
    Factoryϝιου͸ίϯετϥΫλͱൺֱͯ͠ॊೈੑ͕ߴ͍ͨΊ
    έʔεʹԠͯ͡࢖͏͜ͱΛݕ౼͢Δͱྑ͍
    <ݸਓతݟղ>
    • ίϯετϥΫλΛ࢖͏ͱྑ͍έʔε
    • γϯϓϧ͞Λ௥ٻ͍ͨ͠έʔεʢdata classͰDTO࡞Δ͚ͩͷ࣌ͱ͔యܕྫʣ
    • FactoryϝιουΛ࢖͏ͱྑ͍έʔε
    • ॊೈੑΛ΋͍ͨͤͨέʔε
    • Πϯελϯεੜ੒ํ๏͕ෳ਺ύλʔϯ͋ΔέʔεʢηΧϯμϦίϯετϥΫλ࢖͏ΑΓ͸Factoryϝιουͷ΄͏໊͕લͱ
    ͔͔Βҙਤ͕Θ͔Γ΍͍͢ʣ
    • Πϯελϯεੜ੒ϩδοΫ͕ෳࡶͳέʔεʢͦ΋ͦ΋ίϯετϥΫλͩͱ࣮ݱͰ͖ͳ͍έʔεʣ
    • Πϯελϯεੜ੒ํ๏Λ͋Δఔ౓੍ݶ͍ͨ͠έʔεʢίϯετϥΫλͩͱࣗ༝౓͕ߴ͗͢Δͱײ͡Δέʔεʣ
    

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13. ໨࣍
    1. ίϯετϥΫλΑΓFactoryϝιου͕༏Ε͍ͯΔ఺ 5ͭ
    2. KotlinͰͷFactoryϝιου࣮૷ͷॻ͖ํ 5ύλʔϯ
    

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14. ᶃ Companion Object Factory Function
    • Javaͷstaticؔ਺ͱࣅ͍ͯΔҰ൪ΦʔιυοΫεͳॻ͖ํ
    

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15. ᶄ Top-Level Factory Function
    • listOf, mapOfͱ͔͸͜ͷύλʔϯ
    • publicʹͯ͠ϓϩδΣΫτશମͰ࢖͏utilityؔ਺ʹ΋
    • privateʹͯ͠ϑΝΠϧ಺ͰͷΈ༗ޮͳFactoryؔ਺ʹ΋
    

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16. ᶅ Extension Factory Function
    • companion object͕ʢྫ͑͹ϥΠϒϥϦ಺ʹ͋ΔͳͲͯ͠ʣमਖ਼Ͱ͖ͳ͍
    ͱ͖ʹ༗༻
    

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17. ᶆ Fake Constructors
    

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18. ᶇ Methods on Factory Class
    • ͍ΘΏΔBuilderύλʔϯ
    • KotlinͩͱBuilderύλʔϯΛ࢖͏΂͖έʔε͸গͳ͍ʢ໊લ෇͖Ҿ਺ɾσϑΥϧτҾ਺Ͱ୅ସՄೳʣ
    

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19. ݸਓతݟղ
    • جຊతʹ͸ύλʔϯᶃɾᶄͷΈͰे෼
    • ଞͷύλʔϯ͸಄ͷମૢ
    • ʰͲͷύλʔϯʹ͢Δ͔ʱΑΓ΋
    ʰίϯετϥΫλʹ͢Δ͔Factoryϝιουʹ͢Δ͔ʱͷ΄͏͕େࣄ
    

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20. ձࣾએ఻
    smartroundͰ͸ݱࡏΤϯδχΞΛઈࢍืू͍ͯ͠·͢ʂʢ˞෭ۀՄɾϑϧϦϞʔτʣ
    ࿩͚ͩฉ͖͍ͨํ΋େ׻ܴͳͷͰWantedlyɾTwitter DM͔Β͓ؾܰʹ͝Ԡื͍ͩ͘͞ʂ
    ɾελʔτΞοϓ1,800ࣾɾ౤ࢿՈ100͕ࣾར༻
    ɾKotlinɾVue.jsɾAWSΛར༻
    ɾࣾһ਺10໊௒ͷϑΣʔζͰݱࡏੵۃ࠾༻த
    

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21. ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠
    @doyaaaaaken
    

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