Builder for dynamic objects?


#1

I wonder why there is not builder constructor for dynamic objects in kotlin-js standard library.
I am playing around with calling javascript library from kotlin code and configuration object looks like that:

json(
                "width" to "100%",
                "height" to "400px",

                "controller" to json(
                        "loadData" to { filter: dynamic ->
                            println("loading items with filter: $filter")
                            data.toTypedArray()
                        },
                        "insertItem" to { item: dynamic ->
                            println("inserting item: $item")
                            val point = DataPoint(
                                    phi1 = item.phi1,
                                    psio = item.psio,
                                    psie = item.psie
                            )
                            _data.add(point)
                            point
                        },
                        "updateItem" to { item: dynamic ->
                            println("updating item: $item")
                            item as Any
                        },
                        "deleteItem" to { item: dynamic ->
                            println("removing item: $item")
                            _data.remove(item as DataPoint)
                            item as Any
                        }
                )
}

It works fine but looks not good at all. but introducing a very simple function:

fun js(builder: dynamic.() -> Unit): dynamic {
        val obj = Any().asDynamic()
        builder.invoke(obj)
        return obj
}

into much cleaner code:

js {
            width = "100%"
            height = "400px"

            controller = js {
                loadData = { filter: dynamic ->
                    println("loading items with filter: $filter")
                    data.toTypedArray()
                }
                insertItem = { item: dynamic ->
                    println("inserting item: $item")
                    val point = DataPoint(
                            phi1 = item.phi1,
                            psio = item.psio,
                            psie = item.psie
                    )
                    _data.add(point)
                    point
                }
                updateItem = { item: dynamic ->
                    println("updating item: $item")
                    item
                }
                deleteItem = { item: dynamic ->
                    println("removing item: $item")
                    _data.remove(item as DataPoint)
                    item
                }
            }
}

Is there a reason why it is not done this way? Or maybe it is already defined somewhere and I just have not found it?


: Operator Please
#2

At the moment you wouldn’t be able to create something like { "0": "" }, because

js { `0` = ''}

doesn’t compile

Otherwise historical reasons I guess.