sealed class in Kotlin1.1

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1. Copyright © Sansan, Inc. All rights reserved. > sealed class in Kotlin1.1 Jumpei Yamamoto 2017.4.4 第5回 Kotlin勉強会 in Sansan #kotlin_sansan
2. Copyright © Sansan, Inc. All rights reserved. > ⾃⼰紹介 - ⼭本純平 - Sansan株式会社 Eight事業部 - EightのAndroidアプリの開発 - twitter: @boohbah - github: https://github.com/yamamotoj
3. Copyright © Sansan, Inc. All rights reserved. 3
4. Copyright © Sansan, Inc. All rights reserved. > Agenda - テーマ：sealed class in Kotlin 1.1 - sealed classとは - Kotlin 1.1での変更点
5. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() }
6. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } 4JOHMFUPOΦϒδΣΫτ
   
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7. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } Ҿ਺Λ࣋ͭΫϥε
   
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8. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } fun value(color: Color) = when(color){ Color.Red -> "#FF0000" Color.Green -> "#FF0000" Color.Blue -> "#FF0000" is Color.RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) } FMTFઅ͕͍Βͳ͍
9. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } fun value(color: Color) = when(color){ // Color.Red -> "#FF0000" Color.Green -> "#FF0000" Color.Blue -> "#FF0000" is Color.RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) } ϏϧυΤϥʔ
10. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } fun value(color: Color) = when(color){ Color.Red -> "#FF0000" Color.Green -> "#FF0000" Color.Blue -> "#FF0000" is Color.RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) } ໢ཏੑΛνΣοΫ
11. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } fun value(color: Color) { when(color){ // Color.Red -> "#FF0000" Color.Green -> "#FF0000" Color.Blue -> "#FF0000" is Color.RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) } } ϏϧυΤϥʔʹͳΒͳ͍ͷͰ஫ҙ
12. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } fun value(color: Color) = when(color){ Color.Red -> "#FF0000" Color.Green -> "#FF0000" Color.Blue -> "#FF0000" is Color.RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) } εϚʔτΩϟετͰ஋͕ΛͱΓͩͤΔ
13. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } 代数的データ型（直和型） - 互いに交わらない集合の和 - これ以外の値をもたない （厳密には上記Color型は直和型ではない）
14. Copyright © Sansan, Inc. All rights reserved. > 代数的データ型の例 sealed class Bool { object True : Bool() object False : Bool() }
15. Copyright © Sansan, Inc. All rights reserved. > 代数的データ型の例 sealed class Optional<T> { class Some<T>(val v:T) : Option<T>() object None: Option<Nothing>() } Nothing型 -> すべてのクラスのサブクラスとなる
16. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) 使いづらかった点
17. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } fun value(color: Color) = when(color){ Color.Red -> "#FF0000" Color.Green -> "#FF0000" Color.Blue -> "#FF0000" is Color.RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) }
18. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } fun value(color: Color) = when(color){ Color.Red -> "#FF0000" Color.Green -> "#FF0000" Color.Blue -> "#FF0000" is Color.RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) } $PMPSΛ͚ͭΔඞཁ͕͋Δ
19. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() } // ΦϒδΣΫτͲ͏͠Λൺֱ͢Δ val b = Color.RGB(0,0,0) == Color.RGB(0,0,0) b => false
20. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.0) sealed class Color { object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color(){ override fun equals(other: Any?): Boolean { if (this === other) return true if (other?.javaClass != javaClass) return false other as RGB if (r != other.r) return false if (g != other.g) return false if (b != other.b) return false return true } override fun hashCode(): Int { var result = r result = 31 * result + g result = 31 * result + b return result } } }
21. Copyright © Sansan, Inc. All rights reserved. > Kotlin 1.1
22. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() - sealed class のサブクラスをトップレベルに記述できる - sealed class のサブクラスは親クラスと同じファイル上 に定義する必要がある。
23. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() class RGB(val r: Int, val g: Int, val b: Int) : Color() fun value(color: Color) = when(color){ Red -> "#FF0000" Green -> "#FF0000" Blue -> "#FF0000" is RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) } スッキリ！
24. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() data class RGB(val r: Int, val g: Int, val b: Int) : Color()
25. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() data class RGB(val r: Int, val g: Int, val b: Int) : Color() data class - data classが親クラスをもつことができる - sealed class の⼦クラスとしてdata classを定義できる
26. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() data class RGB(val r: Int, val g: Int, val b: Int) : Color() // ΦϒδΣΫτͲ͏͠Λൺֱ͢Δ val b = RGB(0,0,0) == RGB(0,0,0) b => true
27. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() data class RGB(val r: Int, val g: Int, val b: Int) : Color() fun value(color: Color) = when(color){ Red -> "#FF0000" Green -> "#FF0000" Blue -> “#FF0000" RGB(0,0,0) -> “#000000” is RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) }
28. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() data class RGB(val r: Int, val g: Int, val b: Int) : Color() fun value(color: Color) = when(color){ Red -> "#FF0000" Green -> "#FF0000" Blue -> “#FF0000" RGB(0,0,0) -> “#000000” is RGB ->"#%02X%02X%02X".format(color.r, color.g, color.b) }
29. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() data class RGB(val r: Int, val g: Int, val b: Int) : Color() val (r, g, b) = RGB(0, 0, 0) data class の Destructuring Declarations
30. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() data class RGB(val r: Int, val g: Int, val b: Int) : Color() fun value(color: Color) = when(color){ Red -> "#FF0000" Green -> "#FF0000" Blue -> “#FF0000" is RGB -> { val (r, g, b) = color “#%02X%02X%02X".format(r, g, b) } } ちょっとパターンマッチっぽい （あと⼀歩！）
31. Copyright © Sansan, Inc. All rights reserved. > sealed class (Kotlin 1.1) sealed class Color object Red : Color() object Green : Color() object Blue : Color() data class RGB(val r: Int, val g: Int, val b: Int) : Color() fun value(color: Color) = when(color){ Red -> "#FF0000" Green -> "#FF0000" Blue -> “#FF0000" is RGB -> color.let { (r, g, b) -> “#%02X%02X%02X".format(r, g, b) } } Destructuring in Lambdas (since 1.1)
32. Copyright © Sansan, Inc. All rights reserved. > Kotlin 1.1 sealed class まとめ - sealed classの⼦クラスをトップレベルに配置できるよう になって使⽤時にスッキリ！ - sealed classの⼦クラスに data classを持てるようになっ た - インスタンス同⼠の⽐較がしやすくなった - destructing declarations でちょっとスッキリ
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34. Copyright © Sansan, Inc. All rights reserved. > Enjoy Kotlin1.1 34