2017-05-10 17:21 UTC+0200 Przemyslaw Czerpak (druzus/at/poczta.onet.pl)

* contrib/hbwin/olecore.c
    + added functions which changes default method of NIL conversion to
      OLE variant:
         __oleVariantNil2Null( [<lNewNil2NullFlag>] ) -> <lPrevNil2NullFlag>
      By default NIL values passed to foreign OLE code are converted to
      VT_EMPTY variants. __oleVariantNil2Null( .t. ) changes this behavior
      so NIL values are converted to VT_NULL variants.
    ; Warning: This function was added for tests. Looks that it's expected
               behavior for communication with MS-Excel and allows to use
               NIL as default parameter value but potentially it may create
               problems with some custom OLE interfaces so this modification
               should be widely tested in real life before we change the
               default behavior.

ChangeLog.txt

@@ -10,6 +10,21 @@
      * Change, ! Fix, % Optimization, + Addition, - Removal, ; Comment
  */
 
+2017-05-10 17:21 UTC+0200 Przemyslaw Czerpak (druzus/at/poczta.onet.pl)
+  * contrib/hbwin/olecore.c
+    + added functions which changes default method of NIL conversion to
+      OLE variant:
+         __oleVariantNil2Null( [<lNewNil2NullFlag>] ) -> <lPrevNil2NullFlag>
+      By default NIL values passed to foreign OLE code are converted to
+      VT_EMPTY variants. __oleVariantNil2Null( .t. ) changes this behavior
+      so NIL values are converted to VT_NULL variants.
+    ; Warning: This function was added for tests. Looks that it's expected
+               behavior for communication with MS-Excel and allows to use
+               NIL as default parameter value but potentially it may create
+               problems with some custom OLE interfaces so this modification
+               should be widely tested in real life before we change the
+               default behavior.
+
 2017-05-10 16:39 UTC+0200 Przemyslaw Czerpak (druzus/at/poczta.onet.pl)
   * contrib/hbwin/olecore.c
     - removed support for VT_DECIMAL and VT_PTR arrays from

contrib/hbwin/hbwin.hbx

@@ -432,6 +432,7 @@ DYNAMIC __oleIsDisp
 DYNAMIC __oleVariantGetType
 DYNAMIC __oleVariantGetValue
 DYNAMIC __oleVariantNew
+DYNAMIC __oleVariantNil2Null
 DYNAMIC __oleVariantNullDate
 DYNAMIC __wapi_DEVMODE_Get
 DYNAMIC __wapi_DEVMODE_New

contrib/hbwin/olecore.c

@@ -86,6 +86,7 @@ typedef struct
 {
    HRESULT lOleError;
    HB_BOOL fNullDate;
+   HB_BOOL fNil2Null;
    int     iInit;
 } HB_OLEDATA, * PHB_OLEDATA;
 
@@ -93,6 +94,10 @@ static void hb_oleDataInit( void * cargo )
 {
    PHB_OLEDATA pOleData = ( PHB_OLEDATA ) cargo;
 
+   /* default settings: */
+   pOleData->fNullDate = HB_FALSE;
+   pOleData->fNil2Null = HB_FALSE;
+
 #if defined( HB_OS_WIN_CE )
    if( CoInitializeEx( NULL, COINIT_APARTMENTTHREADED ) == S_OK )
 #else
@@ -148,6 +153,17 @@ static HB_BOOL hb_oleGetNullDateFlag( void )
 }
 
 
+static void hb_oleSetNil2NullFlag( HB_BOOL fNil2Null )
+{
+   hb_getOleData()->fNil2Null = fNil2Null;
+}
+
+static HB_BOOL hb_oleGetNil2NullFlag( void )
+{
+   return hb_getOleData()->fNil2Null;
+}
+
+
 static void hb_olecore_init( void * cargo )
 {
    HB_SYMBOL_UNUSED( cargo );
@@ -799,6 +815,7 @@ static void hb_oleItemToVariantRef( VARIANT * pVariant, PHB_ITEM pItem,
       case HB_IT_TIMESTAMP:
       {
          double dDate = hb_itemGetTD( pItem );
+
          if( dDate == 0 && hb_oleGetNullDateFlag() )
          {
             V_VT( pVariant ) = VT_NULL;
@@ -896,6 +913,11 @@ static void hb_oleItemToVariantRef( VARIANT * pVariant, PHB_ITEM pItem,
          }
          break;
 
+      case HB_IT_NIL:
+         if( hb_oleGetNil2NullFlag() )
+            V_VT( pVariant ) = VT_NULL;
+         /* fallthrough */
+
       default:
          if( pVarRef )
          {
@@ -2602,7 +2624,7 @@ HB_FUNC( __OLEVARIANTNEW )
       hb_errRT_OLE( EG_ARG, 1018, 0, NULL, HB_ERR_FUNCNAME, NULL );
 }
 
-/* __oleVariantNullDate( [<lNewNullFlag>] ) -> <lPrevNullFlag> */
+/* __oleVariantNullDate( [<lNewNullDateFlag>] ) -> <lPrevNullDateFlag> */
 HB_FUNC( __OLEVARIANTNULLDATE )
 {
    hb_retl( hb_oleGetNullDateFlag() );
@@ -2610,6 +2632,14 @@ HB_FUNC( __OLEVARIANTNULLDATE )
       hb_oleSetNullDateFlag( hb_parl( 1 ) );
 }
 
+/* __oleVariantNil2Null( [<lNewNil2NullFlag>] ) -> <lPrevNil2NullFlag> */
+HB_FUNC( __OLEVARIANTNIL2NULL )
+{
+   hb_retl( hb_oleGetNil2NullFlag() );
+   if( HB_ISLOG( 1 ) )
+      hb_oleSetNil2NullFlag( hb_parl( 1 ) );
+}
+
 HB_CALL_ON_STARTUP_BEGIN( _hb_olecore_init_ )
    hb_vmAtInit( hb_olecore_init, NULL );
 HB_CALL_ON_STARTUP_END( _hb_olecore_init_ )