Visual C++-Erweiterungsheader

Die folgende Header, icrsint.h, beschreibt die Schnittstelle, mit der Clients Felder aus einem Recordset in Variablen abrufen können, die in einer Klasse definiert sind, die von CADORecordBinding abgeleitet ist. Sie müssen für jedes Feld, auf das Sie zugreifen möchten, ein ADO-Bindungsmakro angeben.

#ifndef _ICRSINT_H_  
#define _ICRSINT_H_  
  
#include <olectl.h>  
#include <stddef.h>  
  
// forwards  
class CADORecordBinding;  
  
#define classoffset(base, derived) ((DWORD)(static_cast<base*>((derived*)8))-8)  
  
enum ADOFieldStatusEnum  
{     
   adFldOK = 0,  
   adFldBadAccessor = 1,  
   adFldCantConvertValue = 2,  
   adFldNull = 3,  
   adFldTruncated = 4,  
   adFldSignMismatch = 5,  
   adFldDataOverFlow = 6,  
   adFldCantCreate = 7,  
   adFldUnavailable = 8,  
   adFldPermissionDenied = 9,  
   adFldIntegrityViolation = 10,  
   adFldSchemaViolation = 11,  
   adFldBadStatus = 12,  
   adFldDefault = 13  
};  
  
typedef struct stADO_BINDING_ENTRY  
{  
   ULONG      ulOrdinal;  
   WORD       wDataType;  
   BYTE       bPrecision;  
   BYTE       bScale;  
   ULONG      ulSize;  
   ULONG      ulBufferOffset;  
   ULONG      ulStatusOffset;  
   ULONG      ulLengthOffset;  
   ULONG      ulADORecordBindingOffSet;  
   BOOL       fModify;  
} ADO_BINDING_ENTRY;  
  
#define BEGIN_ADO_BINDING(cls) public: \  
   typedef cls ADORowClass; \  
   const ADO_BINDING_ENTRY* STDMETHODCALLTYPE GetADOBindingEntries() { \  
   static const ADO_BINDING_ENTRY rgADOBindingEntries[] = {   
  
//  
// Fixed length non-numeric data  
//  
#define ADO_FIXED_LENGTH_ENTRY(Ordinal, DataType, Buffer, Status, Modify)\  
   {Ordinal, \  
   DataType, \  
   0, \  
   0, \  
   0, \  
   offsetof(ADORowClass, Buffer), \  
   offsetof(ADORowClass, Status), \  
   0, \  
   classoffset(CADORecordBinding, ADORowClass), \  
   Modify},  
  
#define ADO_FIXED_LENGTH_ENTRY2(Ordinal, DataType, Buffer, Modify)\  
   {Ordinal, \  
   DataType, \  
   0, \  
   0, \  
   0, \  
   offsetof(ADORowClass, Buffer), \  
   0, \  
   0, \  
   classoffset(CADORecordBinding, ADORowClass), \  
   Modify},  
  
//  
// Numeric data  
//   
#define ADO_NUMERIC_ENTRY(Ordinal, DataType, Buffer, Precision, Scale, Status, Modify)\  
   {Ordinal, \  
   DataType, \  
   Precision, \  
   Scale, \  
   0, \  
   offsetof(ADORowClass, Buffer), \  
   offsetof(ADORowClass, Status), \  
   0, \  
   classoffset(CADORecordBinding, ADORowClass), \  
   Modify},  
  
#define ADO_NUMERIC_ENTRY2(Ordinal, DataType, Buffer, Precision, Scale, Modify)\  
   {Ordinal, \  
   DataType, \  
   Precision, \  
   Scale, \  
   0, \  
   offsetof(ADORowClass, Buffer), \  
   0, \  
   0, \  
   classoffset(CADORecordBinding, ADORowClass), \  
   Modify},  
  
//  
// Variable length data  
//  
#define ADO_VARIABLE_LENGTH_ENTRY(Ordinal, DataType, Buffer, Size, Status, Length, Modify)\  
   {Ordinal, \  
   DataType, \  
   0, \  
   0, \  
   Size, \  
   offsetof(ADORowClass, Buffer), \  
   offsetof(ADORowClass, Status), \  
   offsetof(ADORowClass, Length), \  
   classoffset(CADORecordBinding, ADORowClass), \  
   Modify},  
  
#define ADO_VARIABLE_LENGTH_ENTRY2(Ordinal, DataType, Buffer, Size, Status, Modify)\  
   {Ordinal, \  
   DataType, \  
   0, \  
   0, \  
   Size, \  
   offsetof(ADORowClass, Buffer), \  
   offsetof(ADORowClass, Status), \  
   0, \  
   classoffset(CADORecordBinding, ADORowClass), \  
   Modify},  
  
#define ADO_VARIABLE_LENGTH_ENTRY3(Ordinal, DataType, Buffer, Size, Length, Modify)\  
   {Ordinal, \  
   DataType, \  
   0, \  
   0, \  
   Size, \  
   offsetof(ADORowClass, Buffer), \  
   0, \  
   offsetof(ADORowClass, Length), \  
   classoffset(CADORecordBinding, ADORowClass), \  
   Modify},  
  
#define ADO_VARIABLE_LENGTH_ENTRY4(Ordinal, DataType, Buffer, Size, Modify)\  
   {Ordinal, \  
   DataType, \  
   0, \  
   0, \  
   Size, \  
   offsetof(ADORowClass, Buffer), \  
   0, \  
   0, \  
   classoffset(CADORecordBinding, ADORowClass), \  
   Modify},  
  
#define END_ADO_BINDING()   {0, adEmpty, 0, 0, 0, 0, 0, 0, 0, FALSE}};\  
   return rgADOBindingEntries;}  
  
//  
// Interface that the client 'record' class needs to support. The ADO Binding entries  
// provide the implementation for this interface.  
//  
class CADORecordBinding  
{  
public:  
   STDMETHOD_(const ADO_BINDING_ENTRY*, GetADOBindingEntries) (VOID) PURE;  
};  
  
//  
// Interface that allows a client to fetch a record of data into class data members.  
//  
struct __declspec(uuid("00000544-0000-0010-8000-00aa006d2ea4")) IADORecordBinding;  
DECLARE_INTERFACE_(IADORecordBinding, IUnknown)  
{  
public:  
   STDMETHOD(BindToRecordset) (CADORecordBinding *pAdoRecordBinding) PURE;  
   STDMETHOD(AddNew) (CADORecordBinding *pAdoRecordBinding) PURE;  
   STDMETHOD(Update) (CADORecordBinding *pAdoRecordBinding) PURE;  
};  
  
#endif // !_ICRSINT_H_  

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