在错误情况下应该返回模板的函数应该返回什么 <T> 值？

Question

I'm quite noob yet in OOP and is my first time handling exceptions and Templates, may be I planned the function in a wrong way... But I would like to know what should I return in this case if the execution goes wrong and the exception is thrown.... what kind of data error return in a function returning a Template? Sorry if I am not clear enough, english is not my mothertongue...

template<typename T>
const T& List<T>::Next()
{
    try
    {
        if (_actual->getNext() == NULL)
            throw out_of_range("No next elements, list out of bounds");
        else
        {
            _actual = _actual->getNext();
            _Position++;
            return _actual->getData();
        }
    }
    catch (out_of_range &e)
    {
        cerr << "Error, " << e.what() << endl << "Position: " << _Position << " Elements: " << _Elements << endl;
    }
// <--- what should I return here?? return NULL;? return 0;? return <T> thrash;??
}

Answer 1

If there's nothing to return then there's nothing to return.

Let the exception propagate, either by not catching it here , or by re-throwing it after your cerr statement with the throw statement:

catch (out_of_range &e)
{
    cerr << "Error, " << e.what() << endl
         << "Position: " << _Position
         << " Elements: " << _Elements << endl;
    throw;
}

Your next question will be how to handle the exception in the calling scope. :)
But at least you won't have to worry about return values any more.