Kotlin DSL in under an hour, DevoxxUK 2023

Transcript

1. Kotlin DSL in under an hour @antonarhipov
3. Why Kotlin?
4. Null-safety Coroutines Multiplatform Syntax Why Kotlin?
5. Null-safety Coroutines Multiplatform Syntax Why Kotlin?
6. Null-safety Coroutines Multiplatform Syntax Why Kotlin?
7. Null-safety Coroutines Multiplatform Syntax Why Kotlin?
8. Null-safety Coroutines Multiplatform Syntax Why Kotlin? DSL
9. “Domain-speci fi c”, i.e.
10. tailored for a speci fi c task “Domain-speci fi c”, i.e.
11. External
12. External VS Internal
13. External VS Internal
14. External VS Internal
15. External VS Internal
16. External VS Internal
17. Internal
20. Exposed https://github.com/JetBrains/Exposed object Cities : Table() { val id = integer("id").autoIncrement().primaryKey() // Column<Int> val name = varchar("name", 50) // Column<String> }
21. Exposed https://github.com/JetBrains/Exposed object Cities : Table() { val id = integer("id").autoIncrement().primaryKey() // Column<Int> val name = varchar("name", 50) // Column<String> } transaction { create (Cities) val tallinnId = Cities.insert { it[name] = "Tallinn" } get Cities.id for (city in Cities.selectAll()) { println("${city[Cities.id]}: ${city[Cities.name]}") } }
22. Kotlin DSL in TeamCity project { vcsRoot(ApplicationVcs) buildType { id("Application") name = "Application" vcs { root(ApplicationVcs) } artifactRules = "target/*jar" steps { maven { goals = "clean package" } } triggers { vcs {} } dependencies { snapshot(Library) {}
23. fun main() { embeddedServer(Netty, port = 8080, host = “0.0.0.0", module = Application :: module).start(wait = true) } fun Application.main() { install(DefaultHeaders) install(CallLogging) routing { get("/") { call.respondHtml { head { title { +"Ktor App" } } body { p { +"Hello from Ktor!" } Ktor + kotlinx.html
24. fun main() { embeddedServer(Netty, port = 8080, host = “0.0.0.0", module = Application :: module).start(wait = true) } fun Application.main() { install(DefaultHeaders) install(CallLogging) routing { get("/") { call.respondHtml { head { title { +"Ktor App" } } body { p { +"Hello from Ktor!" } Ktor + kotlinx.html
25. fun main() { embeddedServer(Netty, port = 8080, host = “0.0.0.0", module = Application :: module).start(wait = true) } fun Application.main() { install(DefaultHeaders) install(CallLogging) routing { get("/") { call.respondHtml { head { title { +"Ktor App" } } body { p { +"Hello from Ktor!" } Ktor + kotlinx.html
26. +
31. They all look similar!
32. foo { bar { baz = "Hello!" qux = quux { corge = "Blah" } } }
33. foo { bar { baz = "Hello!" qux = quux { corge = "Blah" } } }
34. foo { bar { baz = "Hello!" qux = quux { corge = "Blah" } } }
35. foo { bar { baz = "Hello!" qux = quux { corge = "Blah" } } }
36. foo { bar(grault = 1) { baz = "Hello!" qux = quux { corge = "Blah" } } }
37. foo { bar(grault = 1) { baz = "Hello!" qux = quux { corge = Blah() } } }
38. foo { bar(grault = 1) { baz = "Hello!" qux = quux { corge = Blah() } } }
39. Let’s write some code! https://github.com/antonarhipov/kotlin-dsl-examples
40. Let’s write some code! https://github.com/antonarhipov/kotlin-dsl-examples
41. Type-safe builders https://kotlinlang.org/docs/reference/type-safe-builders.html
42. final ClientBuilder builder = new ClientBuilder(); builder.setFirstName("Anton"); builder.setLastName("Arhipov"); final TwitterBuilder twitterBuilder = new TwitterBuilder(); twitterBuilder.setHandle("@antonarhipov"); builder.setTwitter(twitterBuilder.build()); final CompanyBuilder companyBuilder = new CompanyBuilder(); companyBuilder.setName("JetBrains"); companyBuilder.setCity("Tallinn"); builder.setCompany(companyBuilder.build()); final Client client = builder.build(); System.out.println("Created client is: " + client); val client = createClient { firstName = "Anton" lastName = "Arhipov" twitter { handle = "@antonarhipov" } company { name = "JetBrains" city = "Tallinn" } } println("Created client is: " + client.consoleString)
43. //extension property val Client.consoleString: String get() = "${twitter.handle} ${company.name}" //extension method fun Client.toConsoleString(): String { return "${twitter.handle} ${company.name}" }
44. fun createClient(c: ClientBuilder.() -> Unit): Client { val builder = ClientBuilder() c(builder) return builder.build() } fun ClientBuilder.company(t: CompanyBuilder.() -> Unit) { company = CompanyBuilder().apply(t).build() } fun ClientBuilder.twitter(t: CompanyBuilder.() -> Unit) { twitter = TwitterBuilder().apply(t).build() } Lambda with receiver Extension functions
45. In fi x notation https://kotlinlang.org/docs/reference/functions.html
46. dateTime = LocalDateTime.of(2018, Month.DECEMBER, 11, 0, 0) dateTime = 11 December 2018 at (14 hh 0) infix fun Int.December(n: Int) : LocalDate { return LocalDate.of(n, Month.DECEMBER, this) } infix fun LocalDate.at(n: Pair<Int, Int>): LocalDateTime { return this.atTime(n.first, n.second) } infix fun Int.hh(n: Int): Pair<Int, Int> { return Pair(this, n) }
47. Context Receivers KEEP-259 Experimental
48. context(DateContext) @DateDsl infix fun Int.March(n: Int): LD = LD.of(n, Month.MARCH, this) class DateContext Context object Context requirement
49. context(DateContext) @DateDsl infix fun Int.March(n: Int): LD = LD.of(n, Month.MARCH, this) class DateContext fun client(block: context(DateContext) ClientBuilder.() - > Unit): Client { val builder = ClientBuilder() with(DateContext()) { block(builder) } return builder.build() } Context object Context requirement Context requirement Context scope
50. context(DateContext) @DateDsl infix fun Int.March(n: Int): LD = LD.of(n, Month.MARCH, this) class DateContext val client = client { // .. . dob = 24 March 2000 } 24 March 2000 fun client(block: context(DateContext) ClientBuilder.() - > Unit): Client { val builder = ClientBuilder() with(DateContext()) { block(builder) } return builder.build() } Context object Context requirement Context requirement Context scope The function is available in the context scope The function is not available, missing DateContext
51. T.() -> Unit
52. kotlin { youtube = "youtube.com/kotlin" slack = "slack.kotl.in" } me { name = "Anton Arhipov" twitter = "@antonarhipov" slides = speakerdeck.com/antonarhipov code = github.com/antonarhipov }