Fun with DSL in Kotlin

Droidcon Singapore 2018

Transcript

1. DSL DSL DSL fun with{ } @inyaki_mwc
3. Why?
5. DSL
6. DSL Internal External
7. DSL Internal External
8. DSL Internal External https://github.com/gradle/kotlin-dsl
9. DSL Internal External
10. Semantic Model
11. Semantic Model Domain Model !=
12. Internal DSL
13. Internal DSL Expression Builder Function Sequence Nested Clousure
14. Anko
15. Kakao
16. Why?
17. infix
18. description.should(endWith(value))
19. description should endWith(value) description.should(endWith(value))
20. description should endWith(value) description.should(endWith(value))
21. description should endWith(value) description.should(endWith(value)) infix fun <T> T.should(matcher: Matcher<T>)
22. description should endWith(value) description.should(endWith(value)) infix fun <T> T.should(matcher: Matcher<T>)
23. https://github.com/kotlintest
24. https://github.com/kotlintest public infix fun <T> T.should(matcher: (T) -> kotlin.Unit): kotlin.Unit { } public infix fun <T, U : T> T.shouldBe(any: U?): kotlin.Unit { } public infix fun <T> T.shouldHave(matcher: io.kotlintest.Matcher<T>): kotlin.Unit { } public infix fun <T> T.shouldNot(matcher: io.kotlintest.Matcher<T>): kotlin.Unit { } public infix fun <T> T.shouldNotBe(any: kotlin.Any?): kotlin.Unit { }
25. https://github.com/kotlintest public infix fun <T> T.should(matcher: (T) -> kotlin.Unit): kotlin.Unit { } public infix fun <T, U : T> T.shouldBe(any: U?): kotlin.Unit { } public infix fun <T> T.shouldHave(matcher: io.kotlintest.Matcher<T>): kotlin.Unit { } public infix fun <T> T.shouldNot(matcher: io.kotlintest.Matcher<T>): kotlin.Unit { } public infix fun <T> T.shouldNotBe(any: kotlin.Any?): kotlin.Unit { } class MyTests : StringSpec() { init { "length should" { "hello".length shouldBe 5 } } } class Example: StringSpec() { init { "String size" { assertAll { a: String, b: String -> (a + b) should haveLength(a.length + b.length) } } } }
26. data class Salary(private val quantity: Double) { infix fun taxes(amount: Double): Salary { return Salary(quantity - amount) } }
27. data class Salary(private val quantity: Double) { infix fun taxes(amount: Double): Salary { return Salary(quantity - amount) } } fun netSalary(): Salary { val mySalary = Salary(1000.00) return mySalary taxes 200.00 }
28. I am your Father Luke
29. I am your Father Luke Demo
30. lambdas { x, y -> x + y }
31. lambdas Function Types High order Functions Lambdas Expressions
32. Function Types
33. Function Types () -> Unit
34. Function Types () -> Unit (View) -> Unit
35. Function Types () -> Unit (View) -> Unit (String) -> Int
36. Function Types () -> Unit val viewResult : () -> Unit
37. Function Types (View) -> Unit fun drawView(view: (View) -> Unit)
38. Function Types (String) -> Int fun maximVolume() : (String) -> Int
39. lambdas expressions val sum: (Int, Int) -> Int = { x, y -> x + y }
40. lambdas expressions val sum: (Int, Int) -> Int = { x, y -> x + y } val sum = { x: Int, y: Int -> x + y }
41. lambdas expressions val sum: (Int, Int) -> Int = { x, y -> x + y } val sum = { x: Int, y: Int -> x + y } fun formula(a: Double, f: (Double) -> Double): Double = f(a)
42. lambdas expressions val sum: (Int, Int) -> Int = { x, y -> x + y } val sum = { x: Int, y: Int -> x + y } fun formula(a: Double, f: (Double) -> Double): Double = f(a) val value = formula(3.0, { i: Double -> sqrt(i) })
43. lambdas expressions val sum: (Int, Int) -> Int = { x, y -> x + y } val sum = { x: Int, y: Int -> x + y } fun formula(a: Double, f: (Double) -> Double): Double = f(a) val value = formula(3.0, { i: Double -> sqrt(i) }) val value = formula(3.0, { sqrt(it) })
44. lambdas expressions val sum: (Int, Int) -> Int = { x, y -> x + y } val sum = { x: Int, y: Int -> x + y } fun formula(a: Double, f: (Double) -> Double): Double = f(a) val value = formula(3.0, { i: Double -> sqrt(i) }) val value = formula(3.0, { sqrt(it) }) val value = formula(3.0) { sqrt(it) }
45. lambdas Demo
46. lambda with receiver
47. return with(Salary()) { gross = 1000.00 taxes = 200.00 pension = 100.00 calculate() } lambda with receiver
48. return with(Salary()) { gross = 1000.00 taxes = 200.00 pension = 100.00 calculate() } lambda with receiver fun <T, R> with(receiver: T, block: T.() -> R): R = receiver.block()
49. salary { calculate() }
50. class Salary { fun calculate() {} } salary { calculate() }
51. fun salary(f: Salary.() -> Unit): Salary { val salary = Salary() salary.f() return salary } class Salary { fun calculate() {} } salary { calculate() }
52. class Order(val buy: Buy)
53. class Order(val buy: Buy) class Buy(var price: Double, var stopLoss: Double, var marginProfit: Double)
54. class Order(val buy: Buy) class Buy(var price: Double, var stopLoss: Double, var marginProfit: Double) fun order(f: Order.() -> Unit): Order.() -> Unit = f
55. class Order(val buy: Buy) class Buy(var price: Double, var stopLoss: Double, var marginProfit: Double) fun order(f: Order.() -> Unit): Order.() -> Unit = f
56. class Order(val buy: Buy) class Buy(var price: Double, var stopLoss: Double, var marginProfit: Double) fun order(f: Order.() -> Unit): Order.() -> Unit = f
57. order { buy.price = 100.00 buy.marginProfit = 105.00 buy.stopLoss = 98.00 }
58. order { buy { price = 100.00 marginProfit = 105.00 stopLoss = 98.00 } }
59. fun order(f: Order.() -> Unit): Order.() -> Unit = f fun buy(f: Buy.() -> Unit)= {}
60. fun order(f: Order.() -> Unit): Order.() -> Unit = f fun buy(f: Buy.() -> Unit)= {} Demo
61. References https://kotlinlang.org/docs/reference/type-safe-builders.html https://github.com/agoda-com/Kakao https://github.com/gradle/kotlin-dsl
62. @inyaki_mwc Thanks