从另一个 class 监听 PropertyChanged

Question

如何在 class B 中监听来自 class A 的 PropertyChanged 事件？我想听听 属性 从 class A.

的变化

class A : INotifyPropertyChanged
{
        private int _x;

        public int X
        {
            get => _x;
            set
            {
                if (_x == value) return;
                _x = value;
                OnPropertyChanged(nameof(X));
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
}

class B
{
        public B(int x)
        {
            // In this class I want to listen to changes of the property X from class A
        }
}

Answer 1

只听事件：

class B
{
    public A _myA;

    public B(int x)
    {
        _myA = new A();
        _myA.PropertyChanged += A_PropertyChanged;
    }

    private void A_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if (e.PropertyName != nameof(_myA.X)) return;
    }
}