Gradle + Kotlin DSL = ⚡🚀

100% Kotlin codebase for your project? Why not?! Maybe it is time to use only one language for the codebase of our project and for all Gradle scripts. See together news about Gradle 5.0 and Kotlin DSL support production ready!

Find source code of this talk on this GitHub project: https://github.com/GerardPaligot/devfestlille-android

Transcript

1. Gradle + Kotlin DSL = ⚡"
   @GerardPaligot
   

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2. What is a DSL?
   Domain Specific Language
   

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3. node(name = "resources") {
   element(name = "string") {
   attr(key = "name", value = "example")
   string(content = "I'm a bugdroid")
   }
   element(name = "plurals") {
   element(name = "string") {
   attr(key = "name", value = "one")
   string(content = "I have 1 song")
   }
   element(name = "string") {
   attr(attribute = "name" to "other")
   string(content = "I have multiple songs")
   }
   }
   }
   

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4. Promises
   Why should I care about it?
   

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5. Statically typed
   type-safe DSL
   

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6. IDE experience
   

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7. Interoperability with
   existing scripts
   

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8. Maximum readability
   

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9. 100% Kotlin
   

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10. Migration
    Groovy to Kotlin
    

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12. - implementation project(':agenda')
    + implementation project(":agenda")
    

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13. - classpath("com.android.tools.build:gradle:$versions.androidPlugin")
    + classpath("com.android.tools.build:gradle:${versions.androidPlugin}")
    

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14. android {
    defaultConfig {
    - applicationId "com.paligot.devfestlille"
    + applicationId = "com.paligot.devfestlille"
    minSdkVersion versions.minSdk
    targetSdkVersion versions.targetSdk
    - versionCode 1
    - versionName "1.0"
    - testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    + versionCode = 1
    + versionName = "1.0"
    + testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
    }
    }
    

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15. android {
    defaultConfig {
    applicationId = "com.paligot.devfestlille"
    - minSdkVersion versions.minSdk
    - targetSdkVersion versions.targetSdk
    + minSdkVersion(versions.minSdk)
    + targetSdkVersion(versions.targetSdk)
    versionCode = 1
    versionName = "1.0"
    testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
    }
    }
    

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16. - apply plugin: "com.android.library"
    - apply plugin: "kotlin-android"
    - apply plugin: "kotlin-android-extensions"
    - apply plugin: "kotlin-kapt"
    - apply plugin: "androidx.navigation.safeargs.kotlin"
    + plugins {
    + id("com.android.library")
    + id("kotlin-android")
    + id("kotlin-android-extensions")
    + id("kotlin-kapt")
    + id("androidx.navigation.safeargs.kotlin")
    + }
    

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17. include(":app", ":agenda", ":shared")
    rootProject.name = "DevFestLille"
    :app :agenda :shared :buildSrc
    settings.gradle > settings.gradle.kts
    

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18. :app :agenda :shared
    :buildSrc
    → build.gradle.kts
    plugins {
    `kotlin-dsl`
    }
    repositories {
    jcenter()
    }
    

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19. :app :agenda :shared
    object Versions {
    val library = "1.0"
    // ...
    }
    object Dependencies {
    val library = "my.package:library:${Versions.library}"
    // ...
    }
    :buildSrc
    → src/main/kotlin
    → Dependencies.kt
    

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20. :app :agenda :shared
    buildscript {
    repositories {
    google()
    jcenter()
    }
    dependencies {
    classpath(Dependencies.androidPlugin)
    classpath(Dependencies.androidx.navigation.plugin)
    classpath(Dependencies.kotlin.plugin)
    }
    }
    :buildSrc
    build.gradle > build.gradle.kts
    

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21. :app :agenda :shared
    buildscript {
    // ...
    }
    - task clean(type: Delete) {
    - delete rootProject.buildDir
    - }
    + tasks {
    + val clean by registering(Delete::class) {
    + delete(buildDir)
    + }
    + }
    :buildSrc
    build.gradle > build.gradle.kts
    

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22. :agenda
    → build.gradle.kts
    :shared
    → build.gradle.kts
    plugins {
    // ...
    }
    android {
    compileSdkVersion(Versions.targetSdk)
    defaultConfig {
    minSdkVersion(Versions.minSdk)
    targetSdkVersion(Versions.targetSdk)
    versionCode = 1
    versionName = "1.0"
    }
    buildTypes {
    // ...
    }
    dataBinding {
    // ...
    }
    }
    :buildSrc
    :app
    → build.gradle.kts
    

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23. :agenda
    → build.gradle.kts
    :shared
    → build.gradle.kts
    plugins {
    // ...
    }
    android {
    compileSdkVersion(Versions.targetSdk)
    defaultConfig {
    // ...
    }
    buildTypes {
    - release {
    - minifyEnabled = false
    + named("release") {
    + isMinifyEnabled = false
    proguardFiles(getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro")
    }
    }
    dataBinding {
    // ...
    }
    }
    :buildSrc
    :app
    → build.gradle.kts
    

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24. :app
    → build.gradle.kts
    :agenda
    → build.gradle.kts
    :shared
    → build.gradle.kts
    plugins {
    // ...
    }
    android {
    compileSdkVersion(Versions.targetSdk)
    defaultConfig {
    // ...
    }
    buildTypes {
    // ...
    }
    dataBinding {
    - enable = true
    + isEnabled = true
    }
    }
    :buildSrc
    

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25. Personal Feedback
    Pros & Cons
    

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26. # 100% Kotlin
    

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27. # 100% Kotlin
    API incompatible $
    

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28. % IDE experience
    

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29. % IDE experience
    New module Groovy only &
    

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30. ' Refactoring code
    

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31. ' Refactoring code
    Autocomplete slow (
    

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32. ) Official documentation
    

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33. ) Official documentation
    Not many blog posts *
    

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34. So what?
    Should I migrate to Kotlin?
    

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35. Thank you!
    @GerardPaligot
    

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36. References
    • DevFest Android Sample https://github.com/GerardPaligot/devfestlille-android
    • Gradle Kotlin DSL Primer https://docs.gradle.org/current/userguide/kotlin_dsl.html
    • Migration blog post https://medium.com/@stoltmanjan/migrating-gradle-to-
    kotlin-dsl-in-android-studio-3-3-18651f37227f
    • Migration blog post https://proandroiddev.com/migrating-android-build-scripts-
    from-groovy-to-kotlin-dsl-f8db79dd6737
    

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