Creating function with variable number of arguments or parameters in Dart

Question

I am looking for a way to create a function with a variable number of arguments or parameters in Dart. I know I could create an array parameter instead, but I would prefer to not do that because I'm working on a library where syntactic brevity is important.

For example, in plain JavaScript, we could do something like this (borrowed from here):

function superHeroes() {
  for (var i = 0; i < arguments.length; i++) {
    console.log("There's no stopping " + arguments[i]);
  }
}

superHeroes('UberMan', 'Exceptional Woman', 'The Hunk');

However, in dart, that code will not run. Is there a way to do the same thing in dart? If not, is this something that is on the roadmap?

question from:https://stackoverflow.com/questions/13731631/creating-function-with-variable-number-of-arguments-or-parameters-in-dart

Answer 1

You can't do that for now.

I don't really know if varargs will come back - they were there some times ago but have been removed.

However it is possible to emulate varargs with Emulating functions. See the below code snippet.

typedef OnCall = dynamic Function(List arguments);

class VarargsFunction {
  VarargsFunction(this._onCall);
  
  final OnCall _onCall;

  noSuchMethod(Invocation invocation) {
    if (!invocation.isMethod || invocation.namedArguments.isNotEmpty)
      super.noSuchMethod(invocation);
    final arguments = invocation.positionalArguments;
    return _onCall(arguments);
  }
}

main() {
  final superHeroes = VarargsFunction((arguments) {
    for (final superHero in arguments) {
      print("There's no stopping ${superHero}");
    }
  }) as dynamic;
  superHeroes('UberMan', 'Exceptional Woman', 'The Hunk');
}