With javaScript I can do something like this:
var parameters = {}
for (object in objects) {
if (someCondition(object)) {
parameters.[object.getName()] = object.getValue();
}
}
myFunction(parameters)
The idea is to collect parameters and pass them as object (!) not as array to the function. How do something similar with scala?
This is what Maps are used for. In JavaScript, we use objects interchangeably for "records" and "dictionaries". In Scala, and most statically typed languages, we use Maps instead for the dictionary use case. One advantage of Maps compared to JS dictionaries is that the keys can be of a type different than String.
So I would translate your example as the following, with ObjClass being the class of your objects:
import scala.collection.mutable
val parameters = mutable.Map.empty[String, ObjClass]
for (obj <- objects) {
parameters(obj.name) = obj.value
}
myFunction(parameters)
Note that the above is very imperative, and can be rewritten in a more functional style like this:
val parameters = (
for (obj <- objects)
yield obj.name -> obj.value
).toMap
val parameters = (for (obj <- objects) yield obj.name -> obj.value).toMap returns a Map not parameters object.
parameters object acts essentially in the same way as an associative array, which is implemented as Map in Scala. You get the same behaviour but what you lose is static type inference and verification that is one of the major benefits of a statically typed language.
myFunction?Try with case classes. Define default values as default parameters.
case class Parameters(
param1:String = "a"
param2:Int = 1
)
val params = Parameters("b", 2)
myFunction(params)
val paramsWithDefault = Parameters()
myFunction(paramsWithDefault)
You can get something like jquery $.extend behavior with inbuilt features (case classes and default values) of scala. But actually javascript is a dynamic language where you can merge objects, where as scala is static. You define your object in compile time. So what we are doing here is not exactly merging objects.
Furthermore, using parameter objects is not common in scala for clarity of the code.
myFunction is.