when<TResult extends Object?> method

  1. @optionalTypeArgs
TResult when<TResult extends Object?>({
  1. required TResult newMessageArrived(
    1. String chatRoomId,
    2. ChatMessage? message,
    3. String? messageId
    ),
})

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( String chatRoomId,  ChatMessage? message,  String? messageId)  newMessageArrived,}) {final _that = this;
switch (_that) {
case MessengerExternalEventNewMessageArrived():
return newMessageArrived(_that.chatRoomId,_that.message,_that.messageId);}
}