privablic.h

#ifndef INCLUDED_PRIVABLIC_H
#define INCLUDED_PRIVABLIC_H

namespace privablic 
{  
// Generate a static data member of type Stub::type in which to store
// the address of a private member.  It is crucial that Stub does not
// depend on the /value/ of the the stored address in any way so that
// we can access it from ordinary code without directly touching
// private data.
template <class Stub>
struct member
{
  static typename Stub::type value;
}; 
template <class Stub> 
typename Stub::type member<Stub>::value;

// Generate a static data member whose constructor initializes
// member<Stub>::value. This type will only be named in an explicit
// instantiation, where it is legal to pass the address of a private
// member.
template <class Stub, typename Stub::type x>
struct private_member
{
  private_member() { member<Stub>::value = x; }
  static private_member instance;
};
template <class Stub, typename Stub::type x> 
private_member<Stub, x> private_member<Stub, x>::instance;

template<typename Stub>
struct func {
  /* export it ... */
  typedef typename Stub::type type;
  static type ptr;
};

template<typename Stub>
typename func<Stub>::type func<Stub>::ptr;

template<typename Stub, typename Stub::type p>
struct private_method : func<Stub> {
  /* fill it ... */
  struct _private_method {
    _private_method() { func<Stub>::ptr = p; }
  };
  static _private_method private_method_obj;
};

template<typename Stub, typename Stub::type p>
typename private_method<Stub, p>::_private_method private_method<Stub, p>::private_method_obj;
}
#endif