在類調用一個方法時注入對象的屬性改變

Question

如果我有一個成員，構造函數和方法，像這樣

//The injected object exposes a public property of type bool which will raise 
//a NotifyPropertyChangedEvent 
IInjectedObject _injectedObject; 

public someClass(IInjectedObject injectedObject) 
{ 
    _injectedObject = injectedObject; 
} 

public void DoSomething() 
{ 

} 

有沒有一種方法調用的方法在我上課的時候屬性上注入的對象改變了？

Answer 1

您聲明您的接口繼承自INotifyPropertyChanged，因此可合理預期通過「PropertyChanged」事件通知監聽器屬性更改。假設是這樣的：

public interface IInjectedObject : INotifyPropertyChanged 
{ 
    bool MyImportantProperty { get; } 
} 

那麼，你的依賴對象必須監聽INotifyPropertyChanged.PropertyChanged事件：

public class MyDependantClass 
{ 
    public MyDependantClass(IInjectedObject injectedObject) 
    { 
     MyInjectedObject = injectedObject; 
    } 

    // We wrap the private field in a protected property, 
    // to capture the event subscriptions 
    private IInjectedObject _myInjectedObject; 
    protected IInjectedObject MyInjectedObject 
    { 
     get { return _myInjectedObject; } 
     set 
     { 
      // unsubscribe from the old property's event 
      if(_myInjectedObject!= null) 
       _myInjectedObject.PropertyChanged -= OnPropertyChanged; 

      _myInjectedObject= value; 

      // subscribe to the new property's event 
      if(_myInjectedObject!= null) 
       _myInjectedObject.PropertyChanged += OnPropertyChanged; 
     } 
    } 

    private void OnPropertyChanged(object sender, PropertyChangedEventArgs args) 
    { 
     if(args.PropertyName == "MyImportantProperty") 
     { 
      //react to the changed property here! 
     } 
    } 
}