https://kotlinlang.org logo
Channels
Powered by
#announcements
  • p

    pavel

    10/31/2018, 10:28 PM
    now, if you for some reason want to have both scala and kotlin source code in the same project there are issues
  • b

    Bernhard

    10/31/2018, 10:29 PM
    yeah, chicken egg compiler issues
  • b

    Bernhard

    10/31/2018, 10:29 PM
    what should be compiled first
  • p

    pavel

    10/31/2018, 10:29 PM
    we currently have a couple of projects that are a mix of groovy and kotlin and that’s suboptimal
  • p

    pavel

    10/31/2018, 10:29 PM
    we opted for chicken 😀
  • k

    kenkyee

    10/31/2018, 10:30 PM
    We have the same issue with Scala and java in the backend made worse by using Pants for a build tool 😔
    👖 2
  • h

    Hamza

    11/01/2018, 12:43 AM
    list = [1, 2, 3] instead of list = listOf(1, 2, 3)
  • u

    user

    11/01/2018, 6:45 AM
    https://twitter.com/kotlin/status/1057886395681910785 19004 members, 38434 messages in the last month and 299 public channels! Join the conversation on Slack https://slack.kotlinlang.org Twitter
    K 1
    K 14
    S 7
  • p

    phldavies

    11/01/2018, 10:44 AM
    Are there implicit interfaces I can use to match data classes component functions? I'd like to be able to have an extension function for any data class that has 
    component1(): Double
    and 
    component2(): Double
    . I can declare my own interface and have my data classes extend it but it feels like something that should be implicit.
  • i

    iex

    11/01/2018, 12:49 PM
    this compiles:
    Copy code
    var bar: String by Delegates.observable("bar") { property, old, new ->
    println("$property has changed from $old to $new")
}
  • i

    iex

    11/01/2018, 12:49 PM
    but if I make the type 
    String?
    instead of 
    String
    it doesn't. How do I fix it?
  • i

    iex

    11/01/2018, 12:54 PM
    Error:(15, 24) Property delegate must have a 'setValue(Foo, KProperty<*>, String?)' method. None of the following functions is suitable:
    public abstract operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String): Unit defined in kotlin.properties.ReadWriteProperty`
  • d

    Dias

    11/01/2018, 12:54 PM
    Copy code
    var bar: String? by Delegates.observable("bar") { property, old: String?, new: String? ->
        println("$property has changed from $old to $new")
    }
  • i

    iex

    11/01/2018, 12:55 PM
    ah got it, was just typing that
  • i

    iex

    11/01/2018, 12:55 PM
    I did an attempt where it set only the optional on 
    new
    🙈
  • i

    iex

    11/01/2018, 12:55 PM
    thanks
  • i

    ilya.gorbunov

    11/01/2018, 1:13 PM
    @iex Or specify the type argument of the delegate explicitly
    Copy code
    var bar by Delegates.observable<String?>("bar") { property, old, new ->
    println("${property.name} has changed from $old to $new")
}
    That's a known problem in type inference https://youtrack.jetbrains.com/issue/KT-10930
  • i

    iex

    11/01/2018, 1:13 PM
    that's better, thanks!
  • b

    Bernhard

    11/01/2018, 1:34 PM
    why are delegates (e.g. stuff by cssclass()) used so frequently?
  • b

    Bernhard

    11/01/2018, 1:34 PM
    why not use a class
  • a

    agrosner

    11/01/2018, 1:34 PM
    convenience. outside consumers treat it as if its the object
  • b

    Bernhard

    11/01/2018, 1:35 PM
    to me it looks like they are simply objects which only hold one value
  • b

    Bernhard

    11/01/2018, 1:35 PM
    and allow you to override get/set for that value
  • a

    agrosner

    11/01/2018, 1:36 PM
    You can “type” it to something like 
    String
    ., so when you use it you dont have to do 
    object.value
    or 
    object.get()
    you can just use 
    object
  • b

    Bernhard

    11/01/2018, 1:37 PM
    right, I get the lazy use case
  • a

    agrosner

    11/01/2018, 1:37 PM
    yes they hold one value, but you keep the API of the property the same without outside or inside consumers need to know exactly how it gets its value
  • b

    Bernhard

    11/01/2018, 1:38 PM
    ah, so you can keep compatibility and pimp values later on
  • a

    agrosner

    11/01/2018, 1:39 PM
    like say you have:
    Copy code
    val age = calculateAge()
    and then you realize, hey i cant do this on class creation because now 
    calculateAge()
    now depends on another property set later. but you dont want to change the API or have to rewrite all usages of 
    age
    to use 
    age.get()
    or something.
  • a

    agrosner

    11/01/2018, 1:40 PM
    so you can change it to:
    Copy code
    val age by lazy { calculateAge(someOtherVar) }
    and then thats it
  • b

    Bernhard

    11/01/2018, 1:40 PM
1...329532963297...3338Latest