Dart Annotation - Unable to pass non constant method-CodePudding

How can I pass-in non-constant method in Dart Annotations?

Here is my annotation:


class Injectable {
  final String name;
  final Scope scope;
  final List<Provider>? provider;

  const Injectable({this.name = '', this.scope = Scope.factory, this.provider});
}


class Provider<T> {
  final Type? useClass;
  final Object? useValue;
  final T? Function()? usefactory;
  final List<Type> deps;

 const Provider(
      {this.useClass, this.useValue, this.usefactory, this.deps = const []});
}

This works fine:

But when I try to directly pass-in the function. I am getting a compile error:

Any idea what is happening?

Error:
Arguments of a constant creation must be constant expressions. (Documentation)
Try making the argument a valid constant, or use 'new' to call the constructor.

Invalid constant value.

The argument type 'ServiceA' can't be assigned to the parameter type 'ServiceA? Function()?'. (Documentation)

CodePudding user response：

Please try to remove the brackets from inject<ServiceA>(). Just make it inject<ServiceA>.

usefactory-s type is a function, but in your case, you are passing ServiceA type data.