What's New in Kotlin 1.3

Transcript

1. O QUE HÁ DE NOVO NO
   KOTLIN 1.3
   Kotlin Meetup SP
   

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2. /_rafaeltoledo
   /rafaeltoledo
   

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3. COROUTINES NÃO SÃO MAIS
   EXPERIMENTAIS
   

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4. KOTLIN NATIVE EM BETA
   

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5. KOTLIN MULTIPLATAFORMA
   

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6. CONTRACTS
   fun foo(s: String?) {
   if (s != null) s.length // Compiler automatically casts 's' to 'String'
   }
   

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7. CONTRACTS
   fun String?.isNotNull(): Boolean = this != null
   fun foo(s: String?) {
   if (s.isNotNull()) s.length // No smartcast :(
   }
   

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8. CONTRACTS
   fun require(condition: Boolean) {
   // This is a syntax form, which tells compiler:
   // "if this function returns successfully, then passed 'condition' is true"
   contract { returns() implies condition }
   if (!condition) throw IllegalArgumentException(...)
   }
   fun foo(s: String?) {
   require(s is String)
   // s is smartcasted to 'String' here, because otherwise
   // 'require' would have throw an exception
   }
   

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9. CAPTURANDO VALOR DO
   when EM UMA VARIÁVEL
   fun Request.getBody() =
   when (val response = executeRequest()) {
   is Success -> response.body
   is HttpError -> throw HttpException(response.status)
   }
   

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10. @JvmStatic e @JvmField
    EM INTERFACES
    interface Foo {
    companion object {
    @JvmField
    val answer: Int = 42
    @JvmStatic
    fun sayHello() {
    println("Hello, world!")
    }
    }
    }
    

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11. @JvmStatic e @JvmField
    EM INTERFACES
    interface Foo {
    public static int answer = 42;
    public static void sayHello() {
    // ...
    }
    }
    

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12. DECLARAÇÕES ANINHADAS
    EM CLASSES DE ANOTAÇÃO
    annotation class Foo {
    enum class Direction { UP, DOWN, LEFT, RIGHT }
    annotation class Bar
    companion object {
    fun foo(): Int = 42
    val bar: Int = 42
    }
    }
    

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13. MAIN SEM PARÂMETROS
    fun main() {
    println("Hello, world!")
    }
    

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14. ATÉ 255 PARÂMETROS EM
    LAMBDAS
    fun trueEnterpriseComesToKotlin(block: (Any, Any, ... /* 42 more */, Any) -> Any) {
    block(Any(), Any(), ..., Any())
    }
    

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15. Experimental
    

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16. INLINE CLASSES
    Inline classes can be viewed as a restricted version of the
    usual classes, in particular, inline classes must have exactly
    one property
    The Kotlin compiler will use this restriction to aggressively
    optimize runtime representation of inline classes and
    substitute their instances with the value of the underlying
    property where possible removing constructor calls, GC
    pressure, and enabling other optimizations
    

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17. INLINE CLASSES
    inline class Name(val s: String)
    fun main() {
    // In the next line no constructor call happens, and
    // at the runtime 'name' contains just string "Kotlin"
    val name = Name("Kotlin")
    println(name.s)
    }
    

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18. UNSIGNED INTEGERS
    // You can define unsigned types using literal suffixes
    val uint = 42u
    val ulong = 42uL
    val ubyte: UByte = 255u
    // You can convert signed types to unsigned and vice versa via stdlib extensions:
    val int = uint.toInt()
    val byte = ubyte.toByte()
    val ulong2 = byte.toULong()
    // Unsigned types support similar operators:
    val x = 20u + 22u
    val y = 1u shl 8
    val z = "128".toUByte()
    val range = 1u..5u
    

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19. @JvmDefault
    interface Foo {
    // Will be generated as 'default' method
    @JvmDefault
    fun foo(): Int = 42
    }
    

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20. Tooling
    

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21. kotlinx.serialization
    kotlinx.serialization is a library which provides
    multiplatform support for (de)serializing objects in Kotlin.
    Previously, it was a separate project, but since Kotlin 1.3, it
    ships with the Kotlin compiler distribution on par with the
    other compiler plugins. The main difference is that you don't
    need to manually watch out for the Serialization IDE Plugin
    being compatible with the Kotlin IDE Plugin version you're
    using: now the Kotlin IDE Plugin already includes serialization!
    

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22. Como começar a experimentar?
    

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23. Links
    WHAT'S COMING IN KOTLIN 1.3
    https://kotlinlang.org/docs/reference/whatsnew13.html
    A MAJOR RELEASE JUST AROUND THE CORNER - KOTLIN 1.3 M2
    https://blog.jetbrains.com/kotlin/2018/08/kotlin-1-3-m2/
    SEE WHAT'S COMING IN KOTLIN 1.3 M1
    https://blog.jetbrains.com/kotlin/2018/07/see-whats-coming-in-kotlin-1-3-m1/
    JETBRAINS TV - KOTLIN CONF 2018
    https://www.youtube.com/user/JetBrainsTV
    23
    

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24. OBRIGADO
    Para perguntas e sugestões:
    Rafael Toledo
    rdtoledo@thoughtworks.com
    

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