TabBarSelection({Key key, T value, @required List<T> values, ValueChanged<T> onChanged, @required Widget child })

Creates a tab bar selection.

The values argument must be non-null, non-empty, and each value must be unique. The value argument must either be null or contained in the values argument. The child argument must be non-null.

Source 

TabBarSelection({
  Key key,
  this.value,
  @required this.values,
  this.onChanged,
  @required this.child
}) : super(key: key)  {
  assert(values != null && values.isNotEmpty);
  assert(new Set<T>.from(values).length == values.length);
  assert(value == null ? true : values.where((T e) => e == value).length == 1);
  assert(child != null);
}