获取对象之间的引用

Question

Following is my code block:

class MyClass: INotifyPropertyChanged
{
     ClearPendingBill cpb;
     public ClearPendingBill CPB
     {
        get { return cpb; }
        set
        {
            cpb = value;
            RaisePropertyChanged("CPB");
        }
     }
}

public partial class ClearPendingBill : UserControl, INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }

    protected bool SetField<T>(ref T field, T value, string propertyName)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return false;
        field = value;
        OnPropertyChanged(propertyName);
        return true;
    }

    double _selected_pending_amt = 0;
    public string SelectedPendingAmount
    {
        get { return "₹ " + string.Format("{0:0,0.00}", _selected_pending_amt); }
        set
        {
            SetField(ref _selected_pending_amt, Convert.ToDouble(value), "SelectedPendingAmount");
        }
    }
}

In the above code object of ClearPendingBill is created inside MyClass. Is it possible somehow to refer MyClass object from ClearPendingBill object?

Answer 1

Of course there is, you have to pass it on construction, or through some other method on ClearPendingBill .

If you wrote:

ClearPendingBill cpb = new ClearPendingBill(this);

It would give it a reference to the owning object (of course you need a constructor to handle it). Static methods on MyClass are always accessible (as long as they are public).

As written though, there is no way to get the owning object.

Answer 2

Not without a back-reference, because the object could be contained by multiple (or no) objects.

I assume you're wanting to notify the containing class that a property has changed. One way to do that is to have MyClass add a handler for the PropertyChanged event of the ClearPendingBill class.