Architecting a Kotlin multiplatform project

Transcript

1. FELIPE LIMA / OCT 4TH, 2018 / KOTLINCONF
   Architecting a Kotlin JVM and
   JS multiplatform project
   

   View Slide

2. FELIPE LIMA / OCT 4TH, 2018 / KOTLINCONF
   Architecting a Kotlin JVM and
   JS multiplatform project
   

   View Slide

3. INTRODUCTION
   

   View Slide

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
   

   View Slide

5. View Slide

6. Kotlin Multiplatform ≠ React Native
   TO MAKE IT CLEAR
   

   View Slide

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

   View Slide

8. Common
   JVM Kotlin/Native Javascript Android
   

   View Slide

9. Common
   Kotlin/Native
   kotlinc kotlin2js
   

   View Slide

10. Common
    Kotlin/Native
    JVM
    kotlinc
    Android
    kotlin2js
    

    View Slide

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

    View Slide

12. A
    Common
    Kotlin/Native
    Dynamic lib iOS
    Executable
    JVM
    kotlinc
    Android
    kotlin2js
    Javascript
    

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

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

    View Slide

17. apply plugin: ‘konan’
    Gradle plugins
    

    View Slide

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

    View Slide

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

    View Slide

20. KEY CONCEPTS
    

    View Slide

21. L
    expect
    Shared module
    actual
    Platform module
    

    View Slide

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
    

    View Slide

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
    

    View Slide

24. expect class Decimal
    Common
    

    View Slide

25. actual typealias Decimal = BigDecimal
    JVM
    

    View Slide

26. actual typealias Decimal = Double
    JS
    

    View Slide

27. expect fun currentTimeMs(): Long
    Common
    

    View Slide

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

    View Slide

29. actual fun currentTimeMs(): Long {
    memScoped {
    val now = alloc()
    gettimeofday(now.ptr, null)
    return (now.tv_sec.toLong() * 1000) +
    (now.tv_usec.toLong() / 1000)
    }
    }
    Kotlin/Native
    

    View Slide

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?
    

    View Slide

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
    

    View Slide

32. DEEP DIVE
    

    View Slide

33. Story time
    

    View Slide

34. View Slide

35. View Slide

36. View Slide

37. View Slide

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

    View Slide

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

    View Slide

40. PPU
    Bitmap
    OpenGL ES
    GLSurfaceView
    

    View Slide

41. expect class Bitmap constructor(
    width: Int,
    height: Int
    ) {
    fun setPixel(x: Int, y: Int, value: Int)
    }
    

    View Slide

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

    View Slide

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)
    }
    }
    

    View Slide

44. actual typealias Bitmap = android.graphics.Bitmap
    

    View Slide

45. PPU
    IntArray
    OpenGL ES
    GLSurfaceView
    

    View Slide

46. internal class PPU(
    internal var buffer: IntArray =
    IntArray(IMG_WIDTH * IMG_HEIGHT)
    // ...
    }
    

    View Slide

47. KEY TAKE AWAYS
    

    View Slide

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
    

    View Slide

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
    

    View Slide

50. THANK YOU!
    

    View Slide