Peder Holt wrote:
On Fri, 10 Dec 2004 03:50:58 -0700, Larry Evans <cppljevans@cox-internet.com> wrote:
On 12/10/2004 03:25 AM, Larry Evans wrote:
where the problem with typedef's is mentioned as the show-stopper.
Actually, Rani Sharoni's post in that thread is the best explanation I've seen to date.
Still, the problem in his post applies to typedefs. If A<T>::B is a nested class or struct under A<T>, and not a typedef, deduction should always be possible.
In the case where B is a typedef: typedef typename some_class<T> B; you can deduce some_class<T> instead of A<T>::B
No, you can't. Given some_class<V> as input to the pattern A<T>::B, you have no way to deduce T. template<class T> struct A { typedef typename arbitrarily_complex_metafunction<T>::type B; }; And of course getting back to iterators, you have no way of determining whether T* is T*, vector<T, A>::iterator, or basic_string<T, Tr, A>::iterator, much less deducing A or Tr.