How to get a Class name dynamically (from a string) in Dart, then create an instance?

Question

I would like to be able to do something like this:

class MyClass() {...}

var class_name = "MyClass"; // user input here
new class_name();           // so here, class_name is supposed to be a class constant

Can anybody suggest a simple way to do it?

Answer 1

One way to do it, is:

library my_library;

import 'dart:mirrors';

void main() {
  var userInput = 'MyClass';
  var symbol = new Symbol(userInput);
  var myClasses = currentMirrorSystem().findLibrary(#my_library).declarations.values.where((dm) => dm is ClassMirror);
  var cm = myClasses.firstWhere((cm) => cm.simpleName == symbol);
  var instance = cm.newInstance(const Symbol(''), []).reflectee;
}

class MyClass {}

If you compile to JS, you should also look into using @MirrorsUsed otherwise the size of the generated JS will be quite large.