whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>({
  1. TResult? inProgress(
    1. int elapsedSeconds,
    2. int totalSeconds,
    3. double? fraction
    )?,
  2. TResult? completed(
    1. int totalSeconds
    )?,
  3. TResult? failed(
    1. String message,
    2. int? code,
    3. int? elapsedSeconds
    )?,
  4. TResult? idle()?,
})

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( int elapsedSeconds,  int totalSeconds,  double? fraction)?  inProgress,TResult? Function( int totalSeconds)?  completed,TResult? Function( String message,  int? code,  int? elapsedSeconds)?  failed,TResult? Function()?  idle,}) {final _that = this;
switch (_that) {
case MeasurementProgressInProgress() when inProgress != null:
return inProgress(_that.elapsedSeconds,_that.totalSeconds,_that.fraction);case MeasurementProgressCompleted() when completed != null:
return completed(_that.totalSeconds);case MeasurementProgressFailed() when failed != null:
return failed(_that.message,_that.code,_that.elapsedSeconds);case MeasurementProgressIdle() when idle != null:
return idle();case _:
  return null;

}
}