Groovy to Kotlin in Buildscripts (Kotlin Night Berlin March 2018)

Pros and cons of migrating build scripts from Groovy to Kotlin. Some examples and how the DSL works under the hood.

Talk recording:
https://www.youtube.com/watch?v=BAuP5Bfp-kk

1. Groovy to Kotlin in build scripts Nelson Osacky
2. •Some Pros and Cons •Examples •How it works under the hood
3. build.gradle -> build.gradle.kts
4. Motivations
5. Kotlin DSL v0.15.6
6. Experiment
7. Pros • Type safety • Auto complete • Kotlin Cons • Slower builds • Less examples • Pre-release state • Source digging
8. type safety
10. if (isCi) { foo }A
11. if (isCi) { foo }A
12. auto-complete
13. • autocompletion gif
14. Slower builds
17. Less docs https://github.com/gradle/kotlin-dsl/tree/master/samples
18. Must dig in source
19. Pros • type safety • better auto complete • kotlin Cons • slower builds • less examples • pre-release state • source digging
20. Examples
21. settings.gradle.kts
22. include ':app' include ':data' include ':service'
23. include( ":app", ":data", ":service" )
24. build.gradle.kts
25. plugins
26. apply plugin: 'java-library' apply plugin: 'kotlin' apply plugin: 'com.android.library' targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 dependencies { testCompile deps.junit compileOnly deps.support.annotations implementation deps.kotlin }
27. apply plugin: 'java-library' apply plugin: 'kotlin' apply plugin: 'com.android.library'
28. plugins { `java-library` kotlin("jvm") id("com.android.library") }A
29. plugins { `java-library` kotlin("jvm") id("com.android.library") }A java { targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 }B dependencies { testImplementation(deps("junit")) compileOnly((deps("support") as Map<*, *>) ["annotations"].toString()) }C
30. plugins { `java-library` kotlin("jvm") id("com.android.library") }A
31. plugins { `java-library` kotlin("jvm") id("com.android.library") }A
32. /** * Applies the given Kotlin plugin [module]. * * For example: `plugins { kotlin("jvm") version "1.2.21" }` * * @param module simple name of the Kotlin Gradle plugin module, for example "jvm", "android", "kapt", "plugin.allopen" etc... */ fun PluginDependenciesSpec.kotlin(module: String): PluginDependencySpec = id("org.jetbrains.kotlin.$module") org.gradle.kotlin.dsl.KotlinDependencyExtensions.kt
33. """ /** * Applies the given Kotlin plugin [module]. * * For example: `plugins { kotlin("jvm") version "$embeddedKotlinVersion" }` * * Visit the [plugin portal](https://plugins.gradle.org/search? term=org.jetbrains.kotlin) to see the list of available plugins. * * @param module simple name of the Kotlin Gradle plugin module, for example "jvm", "android", "kapt", "plugin.allopen" etc... */ fun PluginDependenciesSpec.kotlin(module: String): PluginDependencySpec = id(“org.jetbrains.kotlin.${‘$’}module”) """ 
 buildSrc/src/main/kotlin/codegen/GenerateKotlinDependencyExtensions.kt
34. val generateKotlinDependencyExtensions by task<GenerateKotlinDependencyExtensions> { val publishedPluginsVersion: String by rootProject.extra outputFile = File(apiExtensionsOutputDir, "org/gradle/kotlin/dsl/ KotlinDependencyExtensions.kt") embeddedKotlinVersion = kotlinVersion kotlinDslPluginsVersion = publishedPluginsVersion kotlinDslRepository = kotlinRepo } provider/build.gradle.kts
35. plugins { `java-library` kotlin("jvm") id("com.android.library") }A
36. plugins { `java-library` kotlin("jvm") id("com.android.library") }A
37. /** * The builtin Gradle plugin implemented by [org.gradle.api.plugins.JavaLibraryPlugin]. */ inline val PluginDependenciesSpec.`java-library`: PluginDependencySpec get() = id("org.gradle.java-library") BuiltInPluginExtensions.kt
38. internal fun generateApiExtensionsJar(outputFile: File, gradleJars: Collection<File>, onProgress: () -> Unit) { ApiExtensionsJarGenerator(onProgress = onProgress).generate(outputFile, gradleJars) } org.gradle.kotlin.dsl.codegen.ApiExtensionsJar.kt
39. apply plugin: 'java-library' apply plugin: 'kotlin' targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 dependencies { testImplementation 'junit:junit:4.12' compileOnly 'com.android.support:support- annotations:27.1.0' }A
40. dependencies { testImplementation 'junit:junit:4.12' }A
41. dependencies { testImplementation("junit:junit:4.12") }A
42. plugins { `java-library` kotlin("jvm") } java { targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 } dependencies { testImplementation("junit:junit:4.12") compileOnly("com.android.support:support- annotations:27.1.0") }A
43. apply plugin: 'java-library' apply plugin: 'kotlin' targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 dependencies { testImplementation 'junit:junit:4.12' compileOnly 'com.android.support:support- annotations:27.1.0' }A
44. plugins { `java-library` kotlin("jvm") } java { targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 } dependencies { testImplementation("junit:junit:4.12") compileOnly("com.android.support:support- annotations:27.1.0") }A
45. ext block
46. ext.deps = [ 'junit' : "junit:junit:4.12", 'support' : [ 'annotations': "com.android.support:support-annotations:$ {versions.supportLibrary}", ], ]
47. apply plugin: 'java-library' apply plugin: 'kotlin' targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 dependencies { testImplementation deps.junit compileOnly deps.support.annotations implementation deps.kotlin }W
48. dependencies { testImplementation deps.junit compileOnly deps.support.annotations }W
49. dependencies { testImplementation deps.junit }W
50. dependencies { testImplementation(deps("junit")) }W
51. dependencies { testImplementation deps.junit }Q 
 dependencies { testImplementation(deps("junit")) }W
52. dependencies { testImplementation deps.junit }Q 
 dependencies { testImplementation(deps("junit")) }W fun Project.deps(key: String): Any { return (rootProject.ext["deps"] as Map<*, *>)[key]!! }D
53. fun Project.deps(key: String): Any { return (rootProject.ext["deps"] as Map<*, *>)[key]!! }D
54. fun Project.deps(key: String): Any { return (rootProject.ext["deps"] as Map<*, *>)[key]!! }D ext.deps = [ 'junit' : "junit:junit:4.12", 'support' : [ 'annotations': "com.android.support:support-annotations:$ {versions.supportLibrary}", ], ]
55. fun Project.deps(key: String): Any { return (rootProject.ext["deps"] as Map<*, *>)[key]!! }D
56. dependencies { testImplementation(deps(“junit")) compileOnly((deps("support") as Map<*, *>)["annotations"].toString()) }A fun Project.deps(key: String): Any { return (rootProject.ext["deps"] as Map<*, *>)[key]!! }D
57. plugins { `java-library` kotlin("jvm") } java { targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 }A dependencies { testImplementation(deps("junit")) compileOnly((deps("support") as Map<*, *>)["annotations"].toString()) implementation(deps("kotlin")) }
58. apply plugin: 'java-library' apply plugin: 'kotlin' targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 dependencies { testImplementation deps.junit compileOnly deps.support.annotations implementation deps.kotlin }W
59. targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8
60. java { targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 }A
61. plugins { `java-library` kotlin("jvm") } java { targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 }A dependencies { testImplementation(deps("junit")) compileOnly((deps("support") as Map<*, *>)["annotations"].toString()) implementation(deps("kotlin")) }
62. // Groovy ext.isCi = System.getenv("CI") == "true"
63. // Kotlin extra.set("isCi", System.getenv("CI") == "true")
64. // Groovy ext.isCi = System.getenv("CI") == “true" // Kotlin extra.set("isCi", System.getenv("CI") == "true")
65. val ExtensionAware.isCi : Boolean get() = extra.properties["isCi"].toString().toBoolean()
66. // Groovy if (isCi) { // Do stuff on CI }B
67. // Kotlin if (isCi) { // Do stuff on CI }B
68. // Groovy if (isCi) { // Do stuff on CI }A // Kotlin if (isCi) { // Do stuff on CI }B
69. // Groovy if (isCi) { // Do stuff on CI }A // Kotlin if (isCi()) { // Do stuff on CI }B val ExtensionAware.isCi : Boolean get() = extra.properties["isCi"].toString().toBoolean()
70. • Experiments are fun • Build speeds are slower • Kotlin DSL is still pre-release • Everything is an extension function
71. Thanks nelson.osacky@zenjob.com
 https://www.zenjob.de/careers/ Questions? https://github.com/gradle/kotlin-dsl/tree/master/samples
72. targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8
73. java { targetCompatibility = JavaVersion.VERSION_1_8 sourceCompatibility = JavaVersion.VERSION_1_8 }A
74. public void setSourceCompatibility(Object value) { setSourceCompatibility(JavaVersion.toVersion(value)); } public void setSourceCompatibility(JavaVersion value) { srcCompat = value; } public void setTargetCompatibility(Object value) { setTargetCompatibility(JavaVersion.toVersion(value)); } public void setTargetCompatibility(JavaVersion value) { targetCompat = value; } org.gradle.api.JavaPluginConvention.java
75. public void apply(ProjectInternal project) { project.getPluginManager().apply(JavaBasePlugin.class); JavaPluginConvention javaConvention = project.getConvention() .getPlugin(JavaPluginConvention.class); } org.gradle.api.plugins.JavaPlugin.java
76. /** * Retrieves the [java][org.gradle.api.plugins.JavaPluginConvention] project convention. */ val Project.`java`: org.gradle.api.plugins.JavaPluginConvention get() = convention.getPluginByName<org.gradle.api.plugins.JavaPluginConvention>("java") /** * Configures the [java][org.gradle.api.plugins.JavaPluginConvention] project convention. */ fun Project.`java`(configure: org.gradle.api.plugins.JavaPluginConvention.() -> Unit): Unit = configure(`java`) org.gradle.kotlin.dsl.accessors.kt
77. java { sourceCompatibility = JavaVersion.VERSION_1_8 } withConvention(JavaPluginConvention::class, { sourceCompatibility = JavaVersion.VERSION_1_8 }) (this as HasConvention).convention.getPlugin(JavaPluginConvention::class).run { sourceCompatibility = JavaVersion.VERSION_1_8 }
78. // Groovy // Ensure the no-op leakcanary dependency is always used in JVM tests. configurations.all { config -> if (config.name.contains("UnitTest")) { config.resolutionStrategy.eachDependency { details -> if (details.requested.group == "com.squareup.leakcanary" && details.requested.name == "leakcanary-android") { details.useTarget(group: details.requested.group, name: "leakcanary-android-no-op", version: details.requested.version) }A }B }C }D
79. // Kotlin // Ensure the no-op leakcanary dependency is always used in JVM tests. configurations.all { if (name.contains("UnitTest")) { resolutionStrategy.eachDependency { if (requested.group == "com.squareup.leakcanary" && requested.name == “leakcanary-android") { useTarget(mapOf("group" to requested.group, "name" to "leakcanary-android-no-op", "version" to requested.version)) }A }B }C }D
80. // Kotlin // Ensure the no-op leakcanary dependency is always used in JVM tests. configurations.all { if (name.contains("UnitTest")) { resolutionStrategy.eachDependency { if (requested.group == "com.squareup.leakcanary" && requested.name == “leakcanary-android") { useTarget(mapOf("group" to requested.group, "name" to "leakcanary-android-no-op", "version" to requested.version)) }A }B }C }D
81. // Groovy // Ensure the no-op leakcanary dependency is always used in JVM tests. configurations.all { config -> if (config.name.contains("UnitTest")) { config.resolutionStrategy.eachDependency { details -> if (details.requested.group == "com.squareup.leakcanary" && details.requested.name == "leakcanary-android") { details.useTarget(group: details.requested.group, name: "leakcanary-android-no-op", version: details.requested.version) }A }B }C }D