Is there any Scala feature that allows you to call a method whose name is stored in a string?

Question

Assuming you have a string containing the name of a method, an object that supports that method and some arguments, is there some language feature that allows you to call that dynamically?

Kind of like Ruby's send parameter.

Answer 1

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.)