mapOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? mapOrNull<TResult extends Object?>({
  1. TResult? inProgress(
    1. FetchProgressInProgress value
    )?,
  2. TResult? completed(
    1. FetchProgressCompleted value
    )?,
  3. TResult? failed(
    1. FetchProgressFailed value
    )?,
  4. TResult? idle(
    1. FetchProgressIdle value
    )?,
})

A variant of map that fallback to returning null.

It is equivalent to doing:

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

Implementation

@optionalTypeArgs TResult? mapOrNull<TResult extends Object?>({TResult? Function( FetchProgressInProgress value)?  inProgress,TResult? Function( FetchProgressCompleted value)?  completed,TResult? Function( FetchProgressFailed value)?  failed,TResult? Function( FetchProgressIdle value)?  idle,}){
final _that = this;
switch (_that) {
case FetchProgressInProgress() when inProgress != null:
return inProgress(_that);case FetchProgressCompleted() when completed != null:
return completed(_that);case FetchProgressFailed() when failed != null:
return failed(_that);case FetchProgressIdle() when idle != null:
return idle(_that);case _:
  return null;

}
}