略解reified

Kotlinのreifiedがどのようにして型引数の型情報を取得できるようにしているのかについての解説

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1. ུղ reified CA.kt #5 Roy Sotoyama
2. ࣗݾ঺հ • ֎ࢁ ໆ(Ryo Sotoyama) • @scal_ch • γʔαʔגࣜձࣾ
3. ܕҾ਺ͷࢀর fun isString(obj: Any) = obj is String
4. ܕҾ਺ͷࢀর fun <T> isA(obj: Any) = obj is T
5. ܕҾ਺ͷࢀর fun <T> isA(obj: Any) = obj is T ܕফڈ
6. ܕҾ਺ͷࢀর fun <T> isA(obj: Any) = obj is T inline fun <reified T> f(obj: Any) = obj is T
7. ܕҾ਺ͷࢀর fun <T> isA(obj: Any) = obj is T inline fun <reified T> f(obj: Any) = obj is T inline fun <reified T> f() = T::class.java
8. ܕҾ਺ͷࢀর fun <T> isA(obj: Any) = obj is T inline fun <reified T> f(obj: Any) = obj is T inline fun <reified T> f() = T::class.java
9. inlineؔ਺ fun example() { val v1 = 3 println(noInlineSquare(v1)) } fun noInlineSquare(v: Int) = v * v
10. inlineؔ਺ fun example() { val v1 = 3 println(noInlineSquare(v1)) } fun noInlineSquare(v: Int) = v * v println(noInlineSquare(v1))
11. inlineؔ਺ fun example() { val v1 = 3 println(noInlineSquare(v1)) val v2 = 3 println(inlineSquare(v2)) } fun noInlineSquare(v: Int) = v * v inline fun inlineSquare(v: Int) = v * v println(noInlineSquare(v1))
12. inlineؔ਺ fun example() { val v1 = 3 println(noInlineSquare(v1)) val v2 = 3 println(inlineSquare(v2)) } fun noInlineSquare(v: Int) = v * v inline fun inlineSquare(v: Int) = v * v println(noInlineSquare(v1)) println(v2 * v2)
13. inlineؔ਺ fun example() { val v1 = 3 println(noInlineSquare(v1)) val v2 = 3 println(inlineSquare(v2)) } fun noInlineSquare(v: Int) = v * v inline fun inlineSquare(v: Int) = v * v println(v2 * v2) println(noInlineSquare(v1))
14. reified inline fun <reified T> f(obj: Any) = obj is T
15. reified inline fun <reified T> f(obj: Any) = obj is T fun testIs() { assert(f<String>("kotlin")) }
16. reified inline fun <reified T> f(obj: Any) = obj is T fun testIs() { assert(f<String>("kotlin")) } fun testIs() { assert("kotlin" is T) }
17. reified inline fun <reified T> f(obj: Any) = obj is T fun testIs() { assert(f<String>("kotlin")) } fun testIs() { assert("kotlin" is T) }
18. reified inline fun <reified T> f(obj: Any) = obj is T fun testIs() { assert(f<String>("kotlin")) } fun testIs() { assert("kotlin" is T) } fun testIs() { assert("kotlin" is String) }
19. reifiedͷ஫ҙ఺ • inlineؔ਺ʹ͢Δඞཁ༗ • ܕҾ਺͸࣮ߦ࣌ʹར༻ՄೳͳܕͷΈࢦఆՄ ՄೳɿString, Array<String>, List<*>ͳͲ ෆՄɿNothing, List<String>ͳͲ
20. ·ͱΊ • reified͸ΠϯϥΠϯల։࣌ʹܕΛຒΊࠐΉ • ܕҾ਺ʹ͢΂ͯͷܕΛࢦఆͰ͖ΔΘ͚Ͱ͸ͳ͍