strongIfWeak method

T? strongIfWeak({ bool keepWeakRef = true, })

Promotes this reference to strong only if currently weak.

If this reference is already strong, it is returned unchanged and no manager access handling is triggered.

If currently weak and the object is still reachable:

• A strong reference is restored
• The manager is notified to track the new strong reference

If the object was already garbage-collected:

• The weak reference is cleared
• Returns null

When keepWeakRef is true, the weak reference is preserved alongside the strong one. Otherwise, the weak handle is discarded.

Implementation

T? strongIfWeak({bool keepWeakRef = true}) {
  var ref = _strongRef;
  if (ref != null) {
    // Already a strong reference:
    return ref;
  }

  _strongRef = ref = _weakRef?.target;

  if (ref == null) {
    // Lost reference, not reachable either strongly or weakly:
    _weakRef = null;
  } else {
    if (!keepWeakRef) {
      // Dispose weak reference, but still reachable through `_strongRef`:
      _weakRef = null;
    }

    // Weak ref state, not queued:
    assert(!_queued);

    // New strong reference, handle it:
    final manager = _manager;
    if (manager != null) {
      manager._handleNewStrongRef(this);
      assert(_queued);
    }
  }

  return ref;
}