watch<T> method
Reads the current state of watchable
and rebuilds the widget calling
this methods when the state changes.
Cannot be called outside a build method.
Implementation
T watch<T>(Watchable<T> watchable) {
assert(
widget is LayoutBuilder ||
widget is SliverWithKeepAliveWidget ||
debugDoingBuild,
'Cannot call watch() outside a build method.');
final keys = <BinderKey>[];
return watchScope(watchable, keys).read(watchable, keys);
}