6.2.2 Implementing Dynamic

Extern classes can implement Dynamic and Dynamic<T> which enables arbitrary field access. In the former case, fields can have any type, in the latter, they are constrained to be compatible with the parameter type:

 extern class ImplementsDynamic implements Dynamic<String> {  public var present:Int;  public function new(); } class Main {  static public function main() {  var c = new ImplementsDynamic();  // valid, present is an existing field  c.present = 1;  // valid, assigned value is a String  c.stringField = "foo";  // error, Int should be String  // c.intField = 1;  } } 

Implementing Dynamic does not satisfy the requirements of other implemented interfaces. The expected fields still have to be implemented explicitly.

Trivia: Implementing Dynamic on non-externs

Starting with Haxe 4, implementing Dynamic is only allowed on extern classes. In previous versions any class could implement Dynamic, allowing arbitrary fields to be read or written. Additionally a special resolve method could be used to resolve read access to a non-existend field. A similar feature is now available as field access operator overload on abstracts.

---