//cpeer.h

#ifndef CPEER_H_
#define CPEER_H_

#include <string>
struct CPeer
{
    std::string name;
};
#endif /*CPEER_H_*/

//cpeermanager.h

#ifndef CPEERMANAGER_H_
#define CPEERMANAGER_H_

class CPeer;

#include <boost/shared_ptr.hpp>
#include <boost/scoped_ptr.hpp>


class CPeerManager
{
public:
  CPeerManager();
  boost::scoped_ptr<CPeer> cp_; //error
 // boost::shared_ptr<CPeer> cp_;  // ok
};

#endif /*CPEERMANAGER_H_*/

//cpeermanager.cpp

#include "cpeer.h"
#include "cpeermanager.h"



CPeerManager::CPeerManager():
cp_  (new CPeer() )
{
   
}

//main.cpp

#include "cpeermanager.h"

int main()
{
    CPeerManager cp;
}

i get