David Abrahams wrote:
Vladimir Prus <ghost@cs.msu.su> writes:
but it that I'm not sure what operator++(int) should return...
That's the important question. Writable non-lvalue iterator cannot return a proxy storing the value inside, since there's no value to store. So making iterator_facade return proxy with stored value for all non-lvalue iterators is too simple solution :-(
Actually I think a proxy storing the iterator_facade's "reference" type is probably enough. Think about it.
For writable iterators, that's fine (well, provided it's required that return type of *a is iterator_traits<X>::reference). For readable iterators, you have to store value_type, not reference, since if you store reference, *r++ won't work. The question is how to distinguish between readable and writable iterators. Maybe, using 'is_convertible' on the reference type? BTW, are there any examples of writable iterator made with iterator facade? - Volodya