Kotlin DSL | Modularization for Mobile projects

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Kotlin DSL: Moduralización en proyectos Dinorah Tovar Mobile Engineer @ddinorahtovar @ddinorahtovar @dinorahto @dinorahto Doing code @ Konfio

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What the heck is DSL?

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What is DSL? A domain-specific language (DSL) is a computer language specialized to a particular application domain. This is in contrast to a general-purpose language (GPL), which is broadly applicable across domains. Wikipedia® Domain Speciﬁc Language

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Like, for real? •Provides you a flexible tool •Particular applications •Kotlin used it already

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Has anyone used this before? YES

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For real? Extension.function() + Lambda { //Code }

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Extension Functions //Extension function fun Int.someCoolStuff { this.stuff() }

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Extension Functions //Receiver fun Int.someCoolStuff { this.stuff() }

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Extension Functions //Lambda { () -> doStuff() }

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Extension Functions //Lambda with receiver { () -> this.doStuff() }

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Lets create an DSL function class IsleOfDogs { var type: String? = "" } fun isleOfDogs (lambda: IsleOfDogs.() -> Unit) : IsleOfDogs { return IsleOfDogs().apply(lambda) }

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Extension Functions class IsleOfDogs { var type: String? = "" } fun isleOfDogs (lambda: IsleOfDogs.() -> Unit) : IsleOfDogs { return IsleOfDogs().apply(lambda) }

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A common example with Kotlin fun buildString(action: (StringBuilder).() -> Unit): String { val stringBuilder = StringBuilder() action(stringBuilder) return stringBuilder.toString() }

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A common example with Kotlin buildString { append("<") append(“We love Kotlin at Konﬁo!”) append(">") }

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A common example textView.text = "We love Kotlin at Konﬁo" textView.setOnClickListener { //This is a listener } textView.setTextColor(Color.BLACK)

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Examples: textView.apply { text = "Hola Konﬁo!" setOnClickListener { //This is a listener } textColor(Color.BLACK) }

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Type-safe   Logic in Gradle

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Type-safe model accessors •Dependency and artifact configurations (such as implementation and runtimeOnly contributed by the Java Plugin) •Project extensions and conventions (such as sourceSets) •Elements in the tasks and configurations containers •Elements in project-extension containers (for example the source sets contributed by the Java Plugin that are added to the sourceSets container)

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This talk will not cover this, but here is something cool: https:!//www.youtube.com/watch?v=mAtrEPeAJSc&feature=youtu.be

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Gradle

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Gradle •Declarative elements describe the “what” • The underlying logic creates the “how” • Groovy provides an extensible DSL language

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How Gradle Works? Gradle Task Gradle Build Scripts Gradle Task Gradle Task Gradle task Execution Gradle task Executio Gradle task Executio

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Gradle and Kotlin

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Gradle + Kotlin DSL

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Gradle and Android dependencies { implementation("com.squareup.okio:okio:2.0.0") }

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The real problem: •Editing magic strings is error-prone. •How do I centralize dependencies in a multi-modules project? •Are there newer versions for my libs?

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.kt vs .kts vs .gradle.kts.

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Differences and similarities •They all contain Kotlin Code •.kt files are compiled by the Kotlin compiler •.kts files are executed by the Kotlin scripting support •.gradle.kts are hosted by Gradle

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.gradle.kts ❤ •Kotlin friendly extension of the Gradle API •Delegated properties for Gradle properties and collections •Dynamically generates Kotlin extensions •For models elements contributed by plugins, like task or configuration

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The solution

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The real problem:

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Multimodule projects •Manual Management •Google’s Recommendation using “ext” •Kotlin + buildSrc + DSL

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Multimodule projects //ModuleA - build.gradle implementation "com.android.support:support-annotations:27.0.2" implementation "com.android.support:appcompat-v7:27.0.2" implementation "com.squareup.retrofit2:retrofit:2.3.0" implementation "com.squareup.retrofit2:adapter-rxjava2:2.3.0"

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Multimodule projects //ModuleB - build.gradle implementation "com.android.support:support-annotations:27.0.2" implementation "com.android.support:appcompat-v7:27.0.2" implementation "com.squareup.retrofit2:retrofit:2.3.0" implementation "com.squareup.retrofit2:adapter-rxjava2:2.3.0"

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Multimodule projects ext { versions = [ support_lib: "27.0.2", retrofit: "2.3.0", ] libs = [ support_annotations: "com.android.support:support-annotations:${versions.support_lib}", support_appcompat: "com.android.support:appcompat-v7:${versions.support_lib}", retrofit :"com.squareup.retrofit2:retrofit:${versions.retrofit}" ] }

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Multimodule projects //Module-A / build.gradle implementation libs.support_annotations implementation libs.support_appcompat_v7 implementation libs.retroﬁt implementation libs.retroﬁt_rxjava_adapter implementation libs.rxjava

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The solution •You can create a buildSrc module with Kotlin code to manage dependencies and get IDE completion support.

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The solution •You can create a buildSrc module with Kotlin code to manage dependencies and get IDE completion support.

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The solution •Inside build.gradle.kts

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The solution •Inside Dependencies.kt

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The solution •Inside your App Gradle

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Kotlin DSL: Moduralización en proyectos Dinorah Tovar Mobile Engineer @ddinorahtovar @ddinorahtovar @dinorahto @dinorahto Doing code @ Konfio