Talk about creating your own Domain Specific Language using the power of Kotlin

1. Roll your own
DSL with Kotlin
A lightning talk by Miquel Beltran
Android Developer @ Nebenan.de
@Miqubel

2. What’s a DSL?
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3. android {
compileSdkVersion 26
buildToolsVersion "26.0.2"
defaultConfig {
…
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4. SELECT name FROM users WHERE age >= 30
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5. verticalLayout {
padding = dip(32)
imageView(…).lparams {
margin = dip(16)
gravity = Gravity.CENTER
}
…
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6. // Old School Java Style
val ratingView = RatingView()
ratingView.setStars(3)
ratingView.setMaxStars(5)
// Kotlin DSL Style
rating {
initial = 3
maximum = 5
}
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7. // Creating our DSL
fun rating(func:() -> Unit)
// Using our DSL
rating({})
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8. // Creating our DSL
fun rating(func:() -> Unit)
// Using our DSL
rating({
})
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9. // Creating our DSL
fun rating(func:() -> Unit)
// Using our DSL
rating {
}
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10. // Creating our DSL
fun rating(func:() -> Unit)
// Using our DSL
rating {
initial = 3
maximum = 5
}
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11. // Creating our DSL
fun rating(func: RatingDsl.() -> Unit)
// Using our DSL
rating {
initial = 3
maximum = 5
}
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12. // Creating our DSL
fun rating(func: RatingDsl.() -> Unit)
class RatingDsl(var initial: Int = 1,
var maximum: Int = 5)
// Using our DSL
rating {
initial = 3
maximum = 5
}
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13. // Creating our DSL
fun rating(func: RatingDsl.() -> Unit)
= RatingDsl().apply { func() }
class RatingDsl(var initial: Int = 1,
var maximum: Int = 5)
// Using our DSL
rating {
initial = 3
maximum = 5
}
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14. // Creating our DSL
fun rating(func: RatingDsl.() -> Unit)
= RatingDsl()
.apply { func() }
.build()
class RatingDsl(var initial: Int = 1,
var maximum: Int = 5) {
fun build(): RatingView {
return RatingView().apply {
setStars(initial)
setMaxStars(maximum)
}
}
}
// Using our DSL
rating {
initial = 3
maximum = 5
}
@Miqubel

15. Thanks!
If you would be interested in a full length
talk about this, let me know!
@Miqubel