KotlinによるFactoryメソッド実装パターン

by doyaaaaaken

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KOTLINʹΑΔ  FACTORYϝιου  ࣮૷ύλʔϯ 2019/11/27 KotlinѪ޷ձLT খࢁ ݈ଠ (Koyama Kenta)  Twitter/Github @doyaaaaaken

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ࣗݾ঺հ • ࢓ࣄ • SaaSελʔτΞοϓͰϑϧελοΫΤϯδχΞ(ͱ͍͏໊ͷͳΜͰ΋԰)ͯ͠·͢ • Kotlin͸αʔόαΠυʢJVMʣͰ࢖͍ͬͯ·͢ • झຯ • ອըɾϘʔυήʔϜɾຑ੃ɾςχεɾϙʔΧʔ… • OSSपΓͷ׆ಈ • Kotlin੡OSS΁ͷίϯτϦϏϡʔτ(ktor, Exposed, kotlintest, kohttp) • kotlin-csvͱ͍͏ࣗ࡞OSS࡞ͬͯ·͢ • ktorͷυΩϡϝϯτ೔ຊޠ຋༁ϓϩδΣΫτͷൃىਓͰ͢

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ձࣾ঺հ smartroundגࣜձࣾͰ  ىۀՈɾ౤ࢿՈؒͷ  ࢿۚௐୡϓϩηεΛ؅ཧ͢Δ  SaaSͷ։ൃΛ͍ͯ͠·͢  ʢktor͕1.0.0-betaͷࠒʹ։ ൃελʔτ͠·ͨ͠ʣ https://jp.smartround.com/ ٕज़঺հࢿྉ͸ͪ͜Β https://gitpitch.com/smartround/smartround-tech-presentation

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ࣄͷൃ୺ɻ͜ɺ͜Ε͸…ʁʁ

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ͳ͔ͳ͔໘നͦ͏͡Όͳ͍͔… 1. ຊͳͷʹBeta Releaseͱ͸೗Կʹʁʁ 2. ༗໊ͳEffective XXXγϦʔζ 3. ෷͏ֹۚΛͳΜͱࣗ෼ͰܾΊΕΔ  ʢԼݶ͸͋Γ·͢ʣ

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ࠓճͷൃද಺༰ • શ52ষͷ͏ͪݸਓతʹྑ͔ͬͨͱײͨ͡ষΛൃද • ʰItem33: Consider factory functions instead of constructorsʱ • ҎԼ̎఺ʹ͍ͭͯઆ໌ 1. ͦ΋ͦ΋ͳΜͰίϯετϥΫλΑΓFactoryϝιουͷ΄͏͕  ྑ͍ͷ͔ʁ 2. KotlinͰFactoryϝιου࣮૷͢Δ৔߹ʹ͸Ͳ͏͍͏ॻ͖ํ͕  Φεεϝ͔ʁ

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1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ʰFactoryϝιουʹ͢΂͖8ͭͷཧ༝ʱ͕ॻ͔Ε͍ͯͨͷͰʢϑϧ Ϙοίʣ5ͭʹݫબ͠·͢

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1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ1.  ίϯετϥΫλͱҧͬͯɺؔ਺ʢFactoryϝιουʣʹ͸  ໊લ͕͚ͭΒΕΔ •

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1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ2.  ίϯετϥΫλͱҧͬͯɺؔ਺ʢFactoryϝιουʣ͸  ฦΓ஋ΛαϒλΠϓʹͰ͖Δ •

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1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ3.  ίϯετϥΫλͱҧͬͯɺؔ਺ʢFactoryϝιουʣ͸  ඞͣΠϯελϯεΛੜ੒͢Δඞཁ͸ͳ͍ •

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1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ4.  ؔ਺ʢFactoryϝιουʣ͸ՄࢹੑΛॊೈʹ੍ޚͰ͖Δ •

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1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ5.  ίϯετϥΫλͱؔ਺ʢFactoryϝιουʣ͸  ҟͳΔҾ਺ʹ͢Δ͜ͱ͕Ͱ͖Δ •

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— EffectiveKotlinΑΓ ͳΜ΍͔Μ΍৭ʑཧ༝͋Δ͔Β  ͱΓ͋͑ͣΠϯελϯεੜ੒࣌ ʹ͸FACTORYϝιου࢖͓͏ ” “ ͜͜·Ͱͷ·ͱΊ

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2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • ͳΜͱ5ͭ΋঺հ͞Ε͍ͯ·ͨ͠ 1. Companion object factory function 2. Extension factory function 3. Top-level factory functions 4. Fake constructors 5. Methods on a factory class

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2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 1. Companion object factory function    Javaͱࣅ͍ͯΔ͜ͱɺಛʹ՝୊͕ͳ͍͜ͱ͔Β࠷ਪ঑

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2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 2. Extension factory function    companion object͕ʢྫ͑͹ϥΠϒϥϦ಺ʹ͋ΔͳͲͯ͠ʣमਖ਼͕ Ճ͑ΒΕͳ͍Α͏ͳͱ͖ʹ༗༻ɻ

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2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 3. Top-level factory functions    listOfϝιουͱ͔͸͜ͷύλʔϯɻ  publicʹͨ͠৔߹ɺIDEͷม׵ީิʹग़ͯ͘Δܽ఺͕͋Δɻ  privateʹ͢ΔέʔεͰ͸࢖͍উखྑͦ͞͏ɻ

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2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 4. Fake constructors    ίϯετϥΫλͬΆ͍ݟͨ໨Ͱݺͼग़ͤΔ͕࣮͸ϝιουͰͨ͆͠  ͱ͍͏ύλʔϯɻ  ໋໊ن໿ʹҧ൓͍ͯ͠Δͷ͕ܽ఺ʢϝιουͳͷʹେจࣈ࢝·Γʣ

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2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 5. Methods on a factory class    ͍ΘΏΔBuilderύλʔϯɻ  ͪͳΈʹEffective Kotlinͷ࣍ͷষͰղઆ͞Ε͍ͯΔ͕ɺ  BuilderύλʔϯΛ࢖͏΂͖έʔε͸গͳ͍ɻ  ʢ໊લ෇͖Ҿ਺ɾσϑΥϧτҾ਺Λ࢖͑͹େ఍ࣄ଍ΓΔʣ

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— EffectiveKotlinΑΓ FACTORYϝιουʹ͸  COMPANION OBJECTΛ ࢖͏ͷ͕͍͍ ” “ ͜͜·Ͱͷ·ͱΊ

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• ಉ಺༰ͰɺKotlin Advent Calenderʹ౤ߘ༧ఆͷQiitaهࣄ͕͋Δͷ ͰৄࡉؾʹͳΔํ͸ҎԼΛ͝ࢀর͍ͩ͘͞ • https://qiita.com/doyaaaaaken/items/0c99da9efa7d724a0d80

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HAVE A NICE KOTLIN!