How to implement dynamic properties in Dart?

Question

I would like to be able to back a dynamic property with a Map using a lookup in noSuchMethod(). However the latest changes makes the incoming property reference name unavailable. I can understand the minification scenario requiring us to use Symbols rather than Strings for names, but this makes implementing serializable dynamic properties difficult. Anyone have good ideas on how to approach this problem?

• I can't use String names since the String names are not fixed between calls to the minifier. (This would completely break serialization)

Answer 1

You can access the original name with MirrorSystem.getName(symbol)

So a dynamic class could look like :

import 'dart:mirrors';

class A {
  final _properties = new Map<String, Object>();

  noSuchMethod(Invocation invocation) {
    if (invocation.isAccessor) {
      final realName = MirrorSystem.getName(invocation.memberName);
      if (invocation.isSetter) {
        // for setter realname looks like "prop=" so we remove the "="
        final name = realName.substring(0, realName.length - 1);
        _properties[name] = invocation.positionalArguments.first;
        return;
      } else {
        return _properties[realName];
      }
    }
    return super.noSuchMethod(invocation);
  }
}

main() {
  final a = new A();
  a.i = 151;
  print(a.i); // print 151
  a.someMethod(); // throws
}