whenOrNull<TResult extends Object?> method

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

A variant of when that fallback to returning null

It is equivalent to doing:

switch (sealedClass) {
  case Subclass(:final field):
    return ...;
  case _:
    return null;
}

Implementation

@optionalTypeArgs TResult? whenOrNull<TResult extends Object?>({TResult? Function( String chatRoomId,  ChatMessage? message,  String? messageId)?  newMessageArrived,}) {final _that = this;
switch (_that) {
case MessengerExternalEventNewMessageArrived() when newMessageArrived != null:
return newMessageArrived(_that.chatRoomId,_that.message,_that.messageId);case _:
  return null;

}
}