/// <summary>
 /// 获取附加到 <paramref name="attachedObject"/> 的属性值
 /// </summary>
 /// <param name="attachedObject"></param>
 /// <returns></returns>
 public T GetValue(object attachedObject) =>
 NamedAttachedPropertyExtension.GetNamedAttachedProperty <T>(attachedObject, InnerPropertyKey, _defaultValue);
 /// <summary>
 /// 给 <paramref name="attachedObject"/> 附加 <paramref name="value"/> 值
 /// </summary>
 /// <param name="attachedObject"></param>
 /// <param name="value"></param>
 public void SetValue(object attachedObject, T value) =>
 NamedAttachedPropertyExtension.SetNamedAttachedProperty(attachedObject, InnerPropertyKey, value);