typedef which can be inherited, but isn't available from inside

[KarlisRepsons]

I've tried to sort this out before, but came back with the
following example:

// CAN later access from outside an inherited typedef
template <int N>
struct tdBase { typedef int Xtype; };
template <int N>
struct tdDeri: public tdBase<N>
{
   // BUT
   //Xtype xx = 112; // not declared!
};

const tdDeri<0>::Xtype i = 123;

Why can't it compile?:

Xtype xx = 112;

[Peter87]

You have to write typename tdBase<N>::Xtype xx = 112;

[KarlisRepsons]

I know that. What I desire to read is an explanation of the reasons
why C++ is in that way... Seem like a flaw...

[Cubbi]

The C++FAQ has an article on that: http://www.parashift.com/c++-faq-lite/templates.html#faq-35.18