// ========================================
// method
// ========================================
public void WriteExternal(IMemento memento, ExternalizeContext context)
{
memento.SetConstructorParamKeys(new[] { "ExternalizableProxy.SaveTo", "ExternalizableProxy.LoadFrom" });
memento.WriteSerializable("ExternalizableProxy.SaveTo", _saveTo);
memento.WriteSerializable("ExternalizableProxy.LoadFrom", _loadFrom);
_saveTo(_real, memento, context);
}