Proposal to implement switch expressions throughout the Flutter repo. #136139
Description
switch expressions are designed for specific use cases; several such cases exist in the flutter repo, but right now they're implemented as switch statements.
Example (animation.dart):
String toStringDetails() {
switch (status) {
case AnimationStatus.forward:
return '\u25B6'; // >
case AnimationStatus.reverse:
return '\u25C0'; // <
case AnimationStatus.completed:
return '\u23ED'; // >>|
case AnimationStatus.dismissed:
return '\u23EE'; // |<<
}
}String toStringDetails() {
return switch (status) {
AnimationStatus.forward => '\u25B6'; // >
AnimationStatus.reverse => '\u25C0'; // <
AnimationStatus.completed => '\u23ED'; // >>|
AnimationStatus.dismissed => '\u23EE'; // |<<
};
}They both work, but in my opinion the latter is easier to understand and thus more helpful for debugging.
Additionally, there are places where implementing switch expressions can remove the need for a variable, or allow you to make it final or non-nullable when you otherwise wouldn't be able to:
Example 2 (list_tile.dart):
EdgeInsetsGeometry? padding = widget.padding;
if (padding == null) {
switch (widget._type) {
case _CupertinoListTileType.base:
padding = widget.subtitle == null ? _kPadding : _kPaddingWithSubtitle;
case _CupertinoListTileType.notched:
padding = widget.leading == null ? _kNotchedPaddingWithoutLeading : _kNotchedPadding;
}
}final EdgeInsetsGeometry padding = widget.padding ?? switch (widget._type) {
_CupertinoListTileType.base => widget.subtitle == null ? _kPadding : _kPaddingWithSubtitle,
_CupertinoListTileType.notched => widget.leading == null ? _kNotchedPaddingWithoutLeading : _kNotchedPadding,
};