Is there any Scala feature that allows you to call a method whose name is stored in a string?
You can do this with reflection in Java:
class A {
def cat(s1: String, s2: String) = s1 + " " + s2
}
val a = new A
val hi = "Hello"
val all = "World"
val method = a.getClass.getMethod("cat",hi.getClass,all.getClass)
method.invoke(a,hi,all)
And if you want it to be easy in Scala you can make a class that does this for you, plus an implicit for conversion:
case class Caller[T>:Null<:AnyRef](klass:T) {
def call(methodName:String,args:AnyRef*):AnyRef = {
def argtypes = args.map(_.getClass)
def method = klass.getClass.getMethod(methodName, argtypes: _*)
method.invoke(klass,args: _*)
}
}
implicit def anyref2callable[T>:Null<:AnyRef](klass:T):Caller[T] = new Caller(klass)
a call ("cat","Hi","there")
Doing this sort of thing converts compile-time errors into runtime errors, however (i.e. it essentially circumvents the type system), so use with caution.
(Edit: and see the use of NameTransformer in the link above--adding that will help if you try to use operators.)
Yes. It's called reflection. Here's a link to one way, using some experimental stuff However you should remember that Scala is not a dynamic language, and may not be able to easily do some things that scripting languages can do. You're probably better doing a match on the string, and then calling the right method.
Yes you can!
You would need .invoke()
method of the method object. Simple example below:
import scala.util.Try
case class MyCaseClass(i: String) {
def sayHi = {
println(i)
}
}
val hiObj = MyCaseClass("hi")
val mtdName = "sayHi"
// Method itself as an object
val mtd = hiObj.getClass.getMethod(mtdName)
Try {mtd.invoke(hiObj)}.recover { case _ => ()}
see code here: https://scastie.scala-lang.org/vasily802/WRsRpgSoSayhHBeAvogieg/9