effect function

void effect(void fn())

Runs a side-effect whenever any reactive dependencies used inside fn change.

The effect function tracks all reactive values accessed during the execution of fn. When any of these dependencies update, fn is re-run automatically.

Example:

final count = Reactive<int>(0);

effect(() {
  print('Count changed: ${count.value}');
});
count.value = 1; // Triggers the effect and prints "Count changed: 1"

Implementation

void effect(void Function() fn) {
  late Observer observer;

  // Create an observer that disposes itself and re-runs the effect when triggered
  observer = Observer(() {
    observer.dispose();
    effect(fn);
  });

  // Track dependencies during the initial execution
  Observer.current = observer;
  fn();
  Observer.current = null;
}