Listing 8: Holds object identifier

// Persist.h

#if !defined(PERSIST_H)
#define PERSIST_H

#include <afx.h>    // For BOOL
#include "Connect.h"

class Persist
{
public:
    virtual ~Persist();
    virtual BOOL write() = 0;
    virtual BOOL remove() = 0;
    operator void*() const;

    // Accessors
    long getObjID() const;
    Connection* getConnection() const;

protected:
    Persist(Connection* cp, long id = 0L);

    // Attributes common to all persistent
    // objects:
    long objID;
    Connection* connectp;
    BOOL valid;

private:
    // Disallowed operations
    Persist(const Persist&);
    void operator=(const Persist&);
};

inline Persist::Persist(Connection* cp,
                        long  id)
{
    objID = id;
    connectp = cp;
    connectp->attach();
    // Must be determined in concrete class
    valid = FALSE;              
}

inline long Persist::getObjID() const
{
    return objID;
}

inline Connection* 
Persist::getConnection() const
{
    return connectp;
}

inline Persist::~Persist()
{
    connectp->detach();
}

inline Persist::operator void*() const
{
    return valid ? (void*) this : 0;
}

#endif

/* End of File */