Let's assume that I have following class template:  

<> - read as template 

```
template<template<class T> class Policy>
struct
{

};

```

How (without adding additional params to this <>) can I expose Policy type to external world?  

typedef won't work, and why for the loG can't I write something like this: 

```
typedef Policy<T> Policy;

```

Why can't I use the T type from << param>>? Is this T type unaccessible?