Dart - 带有泛型的类，扩展带有第二类泛型的第二类 - 这可能吗？

Question

Here is the code I would like to do:

abstract class StateBase<E> {
  void restoreState( E target );
  void saveState( E source );
}

class StateController<T extends StateBase<E>> {
  final List<T> _states = [];

  void takeSnapshot( E target ) { ... }
  void addState( T state ) { ... }

But in the line:

class StateController<T extends StateBase<E>> {

When I add the <E> bit it gives me the error:

The name 'E' isn't a type so it can't be used as a type argument.  

Dynamic typing means I can get by with out the 'E' bit, and just use 'StateBase', but I'd prefer the type checking that I can get using the second generic E.

Is this possible to do in Dart?

Thanks for your time!

Answer 1

只需添加E作为另一个类型参数：

class StateController<E, T extends StateBase<E>>