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CdbBdbNTupleT2P.hh

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#ifndef CDBBDBTABLE_NTUPLE_T2P_HH
#define CDBBDBTABLE_NTUPLE_T2P_HH

// File and Version Information:
//      $Id: CdbBdbNTupleT2P.hh,v 1.2 2004/08/06 05:54:31 bartoldu Exp $

#include "CdbBdbTable/CdbBdbNTupleConversionImpl.hh"
#include "CdbBdbTable/CdbBdbNTupleConversionRules.hh"

/// A front-end class for "transient-to-persistent" conversion facility
/**
  * DESCRIPTION:
  *
  *   This class is meant to be used as a primary API for user's code who needs
  *   to convert a transient n-tuple into the corresponding persistent form.
  *   The convertor's design allows to avoid passing explicit template parameters
  *   of (both transient and persistent) n-tuples.
  *
  *   Note that this is a template class having template method(s). The only parameter
  *   of the template class is:
  *
  *     ELEMENT_CONVERSION_RULES
  *
  *   which is a policy for user defined element conversion. The policy is meant
  *   to help in situations when there is no straight-forward mapping between
  *   transient and persistent types of elements, or in cases when a user wishes
  *   to pack rather small transient types (bit strings, enums, etc.) into
  *   bigger persistent elements.
  *
  *     NOTE: this way of transient-to-persistent and vs. transformation
  *           of elements has its own "pros" and "cons".
  *
  *   By default the conversion facility uses default rules for elements conversion.
  *   See class's specialization below.
  *
  * @see class CdbNTupleConversionImpl
  * @see class CdbBdbNTupleConversionRules_UseDefault
  * @see class CdbBdbNTupleConversionRules_Default
  */
template < class ELEMENT_CONVERSION_RULES = CdbBdbNTupleConversionRules_UseDefault >
class CdbBdbNTupleT2P {

public:

  /// Try to convert
  /**
    * @see CdbBdbNTupleConversionImpl::to_persistent()
    */
    template < class        T,
               unsigned int NCOL >
    static CdbStatus convert( ooRef(BdbObject)&                     thePersRef,
                              const CdbCPtr< CdbNTuple< T,NCOL > >& thePtr,
                              const BdbRefAny&                      theHintRef )
    {
        return CdbBdbNTupleConversionImpl< T, NCOL, ELEMENT_CONVERSION_RULES >::to_persistent( thePersRef,
                                                                                               thePtr,
                                                                                               theHintRef );
    }
};

/// A specialized version of the above defined conversion class
/**
  * This class is used when default conversion rules for alements of
  * the class seems to be sufficient. Here is an example of how it can
  * be used:
  *
  *   ooRef(BdbObject)                 pObjectRef;        // A persistent object to be created
  *   CdbCPtr< CdbNTuple< float, 3 > > tuplePtr = ...;    // Have a pointer pointing onto an existing tuple
  *   BdbRefAny                        hintRef = ...;     // Obtain a placement and clustering hint
  *
  *   if( CdbStatus::Success != CdbBdbNTupleT2P<>::convert( pObjectRef, tuplePtr, hintRef )) {
  *       std::cout << "error: failed to convert a transient n-tuple into a persistent." << std::endl;
  *       ...
  *   }
  *
  */
template < >
class CdbBdbNTupleT2P< CdbBdbNTupleConversionRules_UseDefault > {

public:

  /// Try to convert
  /**
    * @see CdbBdbNTupleConversionImpl::to_persistent()
    */
    template < class        T,
               unsigned int NCOL >
    static CdbStatus convert( ooRef(BdbObject)&                     thePersRef,
                              const CdbCPtr< CdbNTuple< T,NCOL > >& thePtr,
                              const BdbRefAny&                      theHintRef )
    {
      // Delegate the actual work to the above defined non-specialized version
      // of the conversion facility.

        return CdbBdbNTupleT2P<  CdbBdbNTupleConversionRules_Default<T> >::convert( thePersRef,
                                                                                    thePtr,
                                                                                    theHintRef );
    }
};

#endif // CDBBDBTABLE_NTUPLE_T2P_HH

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