KotlinによるFactoryメソッド実装パターン

2019/11/27にKotlin愛好会のLTにて発表した内容。
同内容は以下記事にもまとめてあります。
https://qiita.com/doyaaaaaken/items/0c99da9efa7d724a0d80

Transcript

1. KOTLINʹΑΔ
 FACTORYϝιου
 ࣮૷ύλʔϯ 2019/11/27 KotlinѪ޷ձLT খࢁ ݈ଠ (Koyama Kenta)
 Twitter/Github @doyaaaaaken
2. ࣗ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
3. 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
4. ࣄͷൃ୺ɻ͜ɺ͜Ε͸…ʁʁ
5. ͳ͔ͳ͔໘നͦ͏͡Όͳ͍͔… 1. ຊͳͷʹBeta Releaseͱ͸೗Կʹʁʁ 2. ༗໊ͳEffective XXXγϦʔζ 3. ෷͏ֹۚΛͳΜͱࣗ෼ͰܾΊΕΔ
 ʢԼݶ͸͋Γ·͢ʣ
7. ࠓճͷൃද಺༰ • શ52ষͷ͏ͪݸਓతʹྑ͔ͬͨͱײͨ͡ষΛൃද • ʰItem33: Consider factory functions instead of constructorsʱ • ҎԼ̎఺ʹ͍ͭͯઆ໌ 1. ͦ΋ͦ΋ͳΜͰίϯετϥΫλΑΓFactoryϝιουͷ΄͏͕
 ྑ͍ͷ͔ʁ 2. KotlinͰFactoryϝιου࣮૷͢Δ৔߹ʹ͸Ͳ͏͍͏ॻ͖ํ͕
 Φεεϝ͔ʁ
8. 1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ʰFactoryϝιουʹ͢΂͖8ͭͷཧ༝ʱ͕ॻ͔Ε͍ͯͨͷͰʢϑϧ Ϙοίʣ5ͭʹݫબ͠·͢
9. 1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ1.
 ίϯετϥΫλͱҧͬͯɺؔ਺ʢFactoryϝιουʣʹ͸
 ໊લ͕͚ͭΒΕΔ •
10. 1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ2.
 ίϯετϥΫλͱҧͬͯɺؔ਺ʢFactoryϝιουʣ͸
 ฦΓ஋ΛαϒλΠϓʹͰ͖Δ •
11. 1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ3.
 ίϯετϥΫλͱҧͬͯɺؔ਺ʢFactoryϝιουʣ͸
 ඞͣΠϯελϯεΛੜ੒͢Δඞཁ͸ͳ͍ •
12. 1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ4.
 ؔ਺ʢFactoryϝιουʣ͸ՄࢹੑΛॊೈʹ੍ޚͰ͖Δ •
13. 1. FACTORYϝιουͷ΄͏͕ྑ͍ཧ༝ • ͦͷ5.
 ίϯετϥΫλͱؔ਺ʢFactoryϝιουʣ͸
 ҟͳΔҾ਺ʹ͢Δ͜ͱ͕Ͱ͖Δ •
14. — EffectiveKotlinΑΓ ͳΜ΍͔Μ΍৭ʑཧ༝͋Δ͔Β
 ͱΓ͋͑ͣΠϯελϯεੜ੒࣌ ʹ͸FACTORYϝιου࢖͓͏ ” “ ͜͜·Ͱͷ·ͱΊ
15. 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
16. 2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 1. Companion object factory function
 
 Javaͱࣅ͍ͯΔ͜ͱɺಛʹ՝୊͕ͳ͍͜ͱ͔Β࠷ਪ঑
17. 2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 2. Extension factory function
 
 companion object͕ʢྫ͑͹ϥΠϒϥϦ಺ʹ͋ΔͳͲͯ͠ʣमਖ਼͕ Ճ͑ΒΕͳ͍Α͏ͳͱ͖ʹ༗༻ɻ
18. 2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 3. Top-level factory functions
 
 listOfϝιουͱ͔͸͜ͷύλʔϯɻ
 publicʹͨ͠৔߹ɺIDEͷม׵ީิʹग़ͯ͘Δܽ఺͕͋Δɻ
 privateʹ͢ΔέʔεͰ͸࢖͍উखྑͦ͞͏ɻ
19. 2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 4. Fake constructors
 
 ίϯετϥΫλͬΆ͍ݟͨ໨Ͱݺͼग़ͤΔ͕࣮͸ϝιουͰͨ͆͠
 ͱ͍͏ύλʔϯɻ
 ໋໊ن໿ʹҧ൓͍ͯ͠Δͷ͕ܽ఺ʢϝιουͳͷʹେจࣈ࢝·Γʣ
20. 2. FACTORYϝιου࣮૷ɺͲΜͳํ๏͕͋Δʁ • 5. Methods on a factory class
 
 ͍ΘΏΔBuilderύλʔϯɻ
 ͪͳΈʹEffective Kotlinͷ࣍ͷষͰղઆ͞Ε͍ͯΔ͕ɺ
 BuilderύλʔϯΛ࢖͏΂͖έʔε͸গͳ͍ɻ
 ʢ໊લ෇͖Ҿ਺ɾσϑΥϧτҾ਺Λ࢖͑͹େ఍ࣄ଍ΓΔʣ
21. — EffectiveKotlinΑΓ FACTORYϝιουʹ͸
 COMPANION OBJECTΛ ࢖͏ͷ͕͍͍ ” “ ͜͜·Ͱͷ·ͱΊ
22. • ಉ಺༰ͰɺKotlin Advent Calenderʹ౤ߘ༧ఆͷQiitaهࣄ͕͋Δͷ ͰৄࡉؾʹͳΔํ͸ҎԼΛ͝ࢀর͍ͩ͘͞ • https://qiita.com/doyaaaaaken/items/0c99da9efa7d724a0d80
23. HAVE A NICE KOTLIN!