Dart/Flutter - 调用未知混凝土 class 的构造函数（从 Type 获取 class）

Question

I want to call the constructor of a concrete class, but I only have a Type which implements an interface. Is it possible to get the concrete class from that Type and call its constructor without actually having to know it?

My current workaround is a switch with a cast, but that does not seem reasonable, because I have to maintain the switch whenever another class implements that interface.

abstract class IFace {
  String foo();
}

class Bar implements IFace {
  String foo() => 'I am Bar';
}

T? getObject<T extends IFace>() {
  // what I'd like to do, but does not work:
  // return T();
  
  // what I have to do instead:
  switch (T) {
    case Bar:
      return Bar() as T;
    default:
      return null;
  }
}


void main() {
  Bar? bar = getObject<Bar>();
  
  print(bar?.foo()); // I am Bar
}

Answer 1

This is not easy thing to do just because, what if T does not have public constructor, or it has named constructor instead? ;)

I think it could be possible only with use of dart:mirrors package, which is not available on Flutter (due to AOT compilation).

As alternative, you can try using reflectable package, but it is not easy to do either.