Question

I often write code like that:

MyObject property;
MyObject Property
{
    get { return property; }
    set {
            if (property != null)
                property.Changed -= property_Changed; // unsubscribe from the old value
            property = value;
            property.Changed += property_Changed; // subscribe to the new value
        }
}

I’m looking for an elegant way to make the unsubscribing automatic.
Any ideas?

Answer 1

Perhaps using Extensions Methods might be what you are looking for.

You could try something like this.

private MyProperty property;
public MyProperty Property
{
    get { return property; }
    set { property.SubPubValue(value, property_Changed); }
}

private static void property_Changed(object sender, PropertyChangedEventArgs e)
{
    throw new NotImplementedException();
}

public static class Extensions
{
    public static void SubPubValue<T>(this T value, T setValue, PropertyChangedEventHandler property_Changed) where T : MyProperty
    {
        if (setValue != null)
            value.PropertyChanged -= property_Changed;
        value = setValue;
        if (setValue != null)
            value.PropertyChanged += property_Changed;
    }
}