从派生 class 订阅基础 class 事件

Question

我一直在努力从派生 class 订阅基础 class 事件。目的是在我每次更改属性时在我的基础 class 中引发事件，并因此在我的派生 class 中运行一个方法。这是我的代码的简化版本：

namespace MyNamespace
{
public delegate void EventHandler();
[Serializable]
public class ChartGroupCollection : ObservableCollection<ChartGroup>, INotifyCollectionChanged
{

    public ChartGroupCollection()
    {
       base.DirtyFlagging += new EventHandler(MethodIWantToRun); //subscription to event
    }

    void MethodIWantToRun()
    {
        SomeVariable++;
    }


    #region NotifyPropertyChanged
    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
    #endregion
}


[Serializable]
public class ChartGroup : INotifyPropertyChanged
{
    public event EventHandler<EventArgs> DirtyFlagging;
    protected virtual void OnDirtyFlagging(EventArgs e)
    {
        EventHandler<EventArgs> handler = DirtyFlagging;
        if (handler != null)
        {
            handler(this, e);
        }
    }


    public ChartGroup()
    {

    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            DirtyFlagging.Invoke(this, someeventargs);  //Where i want to invoke the event
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }


}

Answer 1

我想你想做这样的事情

public class ChartGroupCollection : ObservableCollection<ChartGroup>
{
    public int SomeVariable { get; set; }

    public ChartGroupCollection()
    {
        CollectionChanged += ChartGroupCollection_CollectionChanged;
    }

    void ChartGroupCollection_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
    {
        if (e.OldItems != null)
        {
            foreach (ChartGroup item in e.OldItems)
            {
                item.PropertyChanged -= item_PropertyChanged;
            }
        }

        if (e.NewItems != null)
        {
            foreach (ChartGroup item in e.NewItems)
            {
                item.PropertyChanged += item_PropertyChanged;
            }
        }
    }

    void item_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        MethodIWantToRun(); 
    }

    private void MethodIWantToRun()
    {
        SomeVariable++;
    }
}

public class ChartGroup : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    int _myProperty;
    public int MyProperty
    {
        set {
            _myProperty = value;
            NotifyPropertyChanged();
        }
    }

    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        if (PropertyChanged != null)
        { 
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

调用触发事件：

ChartGroupCollection chartGroupCollection = new ChartGroupCollection();
var group = new ChartGroup();
chartGroupCollection.Add(group);
group.MyProperty = 3;

从派生 class 订阅基础 class 事件

Subscribe to base class event from derived class

c#

events

derived-class