whenOrNull<TResult extends Object?> method

  1. @optionalTypeArgs
TResult? whenOrNull<TResult extends Object?>(
  1. TResult? $default(
    1. ElementTheme theme,
    2. Map<String, String>? variables,
    3. Map<String, Map<String, String>>? rules,
    4. ElementAppearanceLabels labels,
    )?
)

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( ElementTheme theme,  Map<String, String>? variables,  Map<String, Map<String, String>>? rules,  ElementAppearanceLabels labels)?  $default,) {final _that = this;
switch (_that) {
case _ElementAppearance() when $default != null:
return $default(_that.theme,_that.variables,_that.rules,_that.labels);case _:
  return null;

}
}