Building DSLs

Lightning talk from KUGHH Meetup February 2019

Transcript

5. animation { 0.frame { x = 10 y = 20 } 50.frame { y = 70 rotation = 90 } 100.frame { x = 0 y = -20 rotation = 40 } }
7. /** * Example of a higher-order function */ fun<T, R> Iterable<T>.map(transform: (T) -> R): MutableList<R> { val destination = emptyMutableList<R>() this.forEach { value -> // Invoke the transform function with the current value val transformedValue = transform(value) destination.add(transformedValue) } return destination }
8. /** * Example of a higher-order function */ fun<T, R> Iterable<T>.map(transform: (T) -> R): MutableList<R> { val destination = emptyMutableList<R>() this.forEach { value -> // Invoke the transform function with the current value val transformedValue = transform(value) destination.add(transformedValue) } return destination }
10. /** * Calls the specified function [block] with `this` value * as its receiver and returns `this` value. */ public inline fun <T> T.apply(block: T.() -> Unit): T { contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) } block() return this }
11. /** * Calls the specified function [block] with `this` value * as its receiver and returns `this` value. */ public inline fun <T> T.apply(block: T.() -> Unit): T { contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) } block() return this }
12. /** * Calls the specified function [block] with `this` value * as its receiver and returns `this` value. */ public inline fun <T> T.apply(block: T.() -> Unit): T { contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) } block() return this }
13. /** * Calls the specified function [block] with `this` value * as its receiver and returns `this` value. */ public inline fun <T> T.apply(block: T.() -> Unit): T { contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) } block() return this }
14. /** * Calls the specified function [block] with `this` value * as its receiver and returns `this` value. */ public inline fun <T> T.apply(block: T.() -> Unit): T { contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) } block(this) return this }
15. val user = User(name = "John", age = 30, city = "Berlin") user.apply { age = 31 city = "Hamburg" }
16. val user = User(name = "John", age = 30, city = "Berlin") user.apply { this.age = 31 this.city = "Hamburg" }
17. animation { // This is a higher-order function 0.frame { x = 10 y = 20 } 50.frame { y = 70 rotation = 90 } 100.frame { x = 0 y = -20 rotation = 40 } }
18. class AnimationDSLBuilder { }
19. fun animation(init: AnimationDSLInit) = AnimationDSLBuilder().apply(init)
20. animation { }
21. animation { frame(0) { x = 10 y = 20 } }
22. fun frame(frameNumber: Int, frameBlock: FrameInit) { val frame = Frame().apply(frameBlock) frames[frameNumber] = frame }
23. animation { frame(0) { x = 10 y = 20 } 0.frame { x = 10 y = 20 } }
24. fun Int.frame(frameBlock: FrameInit) { val frame = Frame().apply(frameBlock) frames[this] = frame }
25. animation { frame(0) { x = 10 y = 20 } 0.frame { x = 10 y = 20 } 20 { rotation = 40 } }