---

d_Ref.h

Go to the documentation of this file.

//------------------------------------------------------------------------------
#ifndef d_Ref_h
#define d_Ref_h 1
//------------------------------------------------------------------------------

#include "d_Ref_Any.h"
//------------------------------------------------------------------------------

/**
 * Expresses relationships to objects.
 * 
 * You had to use this class for referencing persistent objects rather than C++
 * pointers. It's implemented as a template class. The user must specify the
 * persistent class (derived from d_Object class) of the relationship as
 * template-argoument. Being a template class there is no need to cast the
 * result to own class.
 * 
 * It can be used as attribute of a class for 1 to 1 relationship between
 * objects of the same or different class.
 * 
 * If it's used as template-argoument of a class container in a class attribute
 * can express 1 to N relationships.
 *
 * LOCATION:
 * d_Ref.h
 *
 * Usage:
 * d_Ref< <linked-class> >              <property-name>;
 * 
 * WHERE:
 * 
 * <linked-class>:      Name of class to link. Can be only a persistent class
 *                  (inherited from d_Object)
 * 
 * <property-name>:     name of property
 *
 * EXAMPLES:
 * class Invoice : public d_Object
 * {
 *    * Relationship 1-1 to customer object
 *   d_Ref<Customer>                    customer;
 * 
 *    * Relationship 1-N to product objects
 *   d_Set< d_Ref<Product> >    products;
 * };
 * 
 *  * Reference to Invoice object 
 * d_Ref<Invoice>       myInvoice;              
 *
 * SEE ALSO:
 * d_Ref_Any, d_Object
 *
 * ODMG:
 * Compliant 
 */

template <class T>
class _ODLL d_Ref : public d_Ref_Any
{
  public:
    /**
     * Default constructor.
     *
     * Creates a null reference.
     *
     * ODMG    :  Compliant 
     */
    d_Ref();

    /**
     * Creates a reference to <iObject> object.
     *
     * ODMG    :  Compliant 
     */
    d_Ref( const T* iObject );

    /**
     * Copy constructor.
     *
     * Copy the reference of <iRef>.
     *
     * ODMG    :  Compliant 
     */
    d_Ref( const d_Ref<T>& iRef );

    /**
     * Creates a reference by the d_Ref_Any object <iRef>.
     *
     * ODMG    :  Compliant 
     */
    d_Ref( const d_Ref_Any& iRef );

    /**
     * Set the reference to <iSource> object.
     *
     * ODMG    :  Compliant 
     */
    d_Ref<T>& operator =( const T* iSource );

    /**
     * Returns the persistent object in memory.
     *
     * If the object is not present in memory Orient ODBMS loads the object
     * from database to memory trasparently.
     *
     * If the reference is null then an exception d_Error_RefNull or
     * d_Error_RefInvalid is raised.
     *
     * This operator permits to handle d_Ref<> as common C++ pointer.
     *
     * SEE ALSO:  operator *(), ptr()
     * ODMG    :  Compliant 
     */
    T* operator -> ();

    /**
     * Returns the persistent object in memory.
     *
     * If the object is not present in memory Orient ODBMS loads the object
     * from storage to memory trasparently.
     *
     * If the reference is null then an exception d_Error_RefNull or
     * d_Error_RefInvalid is raised.
     *
     * SEE ALSO:  operator ->(), ptr()
     * ODMG    :  Compliant 
     */
    T & operator * ();

    /**
     * Returns the persistent object in memory.
     *
     * If the object is not present in memory Orient ODBMS loads the object
     * from storage to memory trasparently.
     *
     * If the reference is null then an exception d_Error_RefInvalid is
     * raised.
     *
     * SEE ALSO:  operator ->(), operator *()
     * ODMG    :  Compliant 
     */
    T * ptr ();

    /**
     * Force loading of object in memory.
     *
     * If the object is not present in memory Orient ODBMS loads the object
     * from storage to memory.
     *
     * If the reference is null then an exception d_Error_RefInvalid is
     * raised.
     *
     * SEE ALSO:  operator ->(), operator *(), ptr()
     * ODMG    :  Extension 
     */
    void load ();
};
//------------------------------------------------------------------------------

#include "d_Ref.cti"
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------

#endif

---