StateHolder

Synchronous state container with change notification. Pure Dart, no Flutter dependency.

late final count = state(0);

count.value = 10;               // Set
count.update((c) => c + 1);     // Transform
count.build((v) => Text('$v'))  // Rebuild on change

Creating State

class CounterViewModel extends ViewModel {
  late final count = state(0);
  late final name = state('');
  late final items = state<List<String>>([]);
}

Automatically disposed when the ViewModel disposes.

Reading and Writing

// Read
int current = vm.count.value;

// Write directly
vm.count.value = 10;

// Transform current value
vm.count.update((c) => c + 1);
vm.items.update((list) => [...list, 'new']);

Building UI

vm.count.build((count) => Text('$count'))

See Building UI for buildWithChild() and other patterns.

Side Effects

For navigation, snackbars, or other effects without rebuilding:

vm.isDeleted.listen(
  onChange: (prev, curr) {
    if (curr) Navigator.of(context).pop();
  },
  child: DeleteButton(),
)

Standalone Usage

Outside ViewModels, manage disposal manually:

final counter = StateHolder(0);
// ...
counter.dispose();

API Summary

Operation	Code
Create	late final count = state(0)
Read	count.value
Write	count.value = 10
Update	count.update((c) => c + 1)
Build UI	count.build((v) => Text('$v'))
Listen	count.listen(onChange: ..., child: ...)