struct inside a class

[George2]

Hello everyone,


For the MSDN sample,

http://msdn2.microsoft.com/en-us/library/2af6btx2.aspx

  template <class U>
      struct rebind { typedef stingyallocator<U> other; };

My question is, what is the purpose of defining an internal struct which has only a type? How to use it? Why class U is different from _Ty?

(I see similar code in STL internal implementation for allocator class, seems like a pattern which I do not know.)


thanks in advance,
George