when<TResult extends Object?> method

  1. @optionalTypeArgs
TResult when<TResult extends Object?>({
  1. required TResult idle(),
  2. required TResult loading(),
  3. required TResult error(
    1. F failure
    ),
  4. required TResult success(
    1. T data
    ),
})

A switch-like method, using callbacks.

As opposed to map, this offers destructuring. It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case Subclass2(:final field2):
    return ...;
}

Implementation

@optionalTypeArgs TResult when<TResult extends Object?>({required TResult Function()  idle,required TResult Function()  loading,required TResult Function( F failure)  error,required TResult Function( T data)  success,}) {final _that = this;
switch (_that) {
case Idle():
return idle();case Loading():
return loading();case Error():
return error(_that.failure);case Success():
return success(_that.data);case _:
  throw StateError('Unexpected subclass');

}
}