Architecting a Kotlin multiplatform project

Transcript

1. FELIPE LIMA / OCT 4TH, 2018 / KOTLINCONF Architecting a

   Kotlin JVM and JS multiplatform project

2. FELIPE LIMA / OCT 4TH, 2018 / KOTLINCONF Architecting a

   Kotlin JVM and JS multiplatform project

3. INTRODUCTION

4. • Yet another cross platform framework? • Not all of

   them are created equal • Several options: React Native, Flutter, Xamarin, PhoneGap, Titanium, Cordova, etc. • Quite unlike all other options • Ideal for business logic code sharing How it works
5. None

6. Kotlin Multiplatform ≠ React Native TO MAKE IT CLEAR

7. Kotlin Multiplatform > C/C++ TO MAKE IT CLEAR

8. Common JVM Kotlin/Native Javascript Android

9. Common Kotlin/Native kotlinc kotlin2js

10. Common Kotlin/Native JVM kotlinc Android kotlin2js

11. Common Kotlin/Native Dynamic lib iOS Executable JVM kotlinc Android kotlin2js

12. A Common Kotlin/Native Dynamic lib iOS Executable JVM kotlinc Android

    kotlin2js Javascript

13. apply plugin: 'kotlin-platform-common' Gradle plugins

14. apply plugin: ‘kotlin-platform-android' Gradle plugins

15. apply plugin: ‘kotlin-platform-jvm’ Gradle plugins

16. apply plugin: ‘kotlin-platform-js’ Gradle plugins

17. apply plugin: ‘konan’ Gradle plugins

18. apply plugin: ‘org.jetbrains.kotlin.frontend’ Gradle plugins

19. dependencies { expectedBy project(':common') } Declaring dependencies

20. KEY CONCEPTS

21. L expect Shared module actual Platform module

22. expect class Order { val id: Int val userId: Int

    val amount: Decimal val feePercent: Decimal val price: Decimal val coinPair: CoinPair val status: OrderStatus val type: OrderType } Common

23. actual data class Order( actual val id: Int, actual val

    userId: Int, actual val amount: Decimal, actual val feePercent: Decimal, actual val price: Decimal, actual val coinPair: CoinPair, actual val status: OrderStatus, actual val type: OrderType, val createdAt: DateTime = DateTime.now(), val updatedAt: DateTime = DateTime.now() ) JVM

24. expect class Decimal Common

25. actual typealias Decimal = BigDecimal JVM

26. actual typealias Decimal = Double JS

27. expect fun currentTimeMs(): Long Common

28. actual fun currentTimeMs(): Long { return System.currentTimeMillis() } JVM

29. actual fun currentTimeMs(): Long { memScoped { val now =

    alloc<timeval>() gettimeofday(now.ptr, null) return (now.tv_sec.toLong() * 1000) + (now.tv_usec.toLong() / 1000) } } Kotlin/Native

30. • Simpler implementation (no factory classes or dep. injection) •

    Interfaces cannot have constructors • All implementations are known at compile time • More flexibility • Top level and extension functions are supported Why not interfaces?

31. • Cannot reference any platform specific code • Can only

    have Kotlin code • Can only depend on other Kotlin common modules or libraries Common module LIMITATIONS AND CAVEATS

32. DEEP DIVE

33. Story time

34. None
35. None
36. None
37. None

38. Console APU PPU CPU Mapper Audio buffer Video buffer Audio

    device Video device

39. Console APU PPU CPU Mapper Audio buffer Video buffer Audio

    device Video device

40. PPU Bitmap OpenGL ES GLSurfaceView

41. expect class Bitmap constructor( width: Int, height: Int ) {

    fun setPixel(x: Int, y: Int, value: Int) }

42. package android.graphics; public final class Bitmap implements Parcelable { //

    ... }

43. typealias AndroidBitmap = android.graphics.Bitmap actual class Bitmap actual constructor(width: Int,

    height: Int) { private val delegate: AndroidBitmap = AndroidBitmap.createBitmap(width, height, RGB_565) actual fun setPixel(x: Int, y: Int, value: Int) { delegate.setPixel(x, y, value) } }

44. actual typealias Bitmap = android.graphics.Bitmap

45. PPU IntArray OpenGL ES GLSurfaceView

46. internal class PPU( internal var buffer: IntArray = IntArray(IMG_WIDTH *

    IMG_HEIGHT) // ... }

47. KEY TAKE AWAYS

48. • Support is still experimental, expect rough edges and breaking

    changes • Very exciting technology • Benefits from a large and quickly growing Kotlin community • Expect the usual top notch tooling support by Jetbrains • You can start trying it out using it right now Key take aways

49. • Makes no assumptions about your system architecture • Not

    a framework, just a platform • Has the potential to turn into an entire ecosystem • Probably will require bigger organizational changes Key take aways

50. THANK YOU!