Microsoft KB Archive/253501

= How to pass a COleDispatchDriver as an argument for a method expecting a VARIANT =

Article ID: 253501

Article Last Modified on 5/14/2007

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APPLIES TO


 * Microsoft Office Word 2007
 * Microsoft Office Word 2003
 * Microsoft Word 2002 Standard Edition
 * Microsoft Word 2000 Standard Edition
 * Microsoft Word 97 Standard Edition
 * Microsoft Office Excel 2007
 * Microsoft Office Excel 2003
 * Microsoft Excel 2002 Standard Edition
 * Microsoft Excel 2000 Standard Edition
 * Microsoft Excel 97 Standard Edition
 * Microsoft Office PowerPoint 2007
 * Microsoft Office PowerPoint 2003
 * Microsoft PowerPoint 2002 Standard Edition
 * Microsoft PowerPoint 2000 Standard Edition
 * Microsoft PowerPoint 97 Standard Edition
 * Microsoft Visual C++ 6.0 Professional Edition
 * Microsoft Foundation Class Library 4.2

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This article was previously published under Q253501



SUMMARY
Some methods require that you pass a VARIANT that represents an Automation object. With MFC, these objects are typically handled by COleDispatchDriver-derived classes. To pass one of these to a method expecting a VARIANT, you can create a new VARIANT that has the vt member set to VT_DISPATCH and the pdispVal member set to the m_lpDispatch of the COleDispatchDriver class.



MORE INFORMATION
The following sample uses Microsoft Office Excel as the Automation server. However, the technique that is illustrated can be used with other Microsoft Office applications also.

Sample code
Excel has several methods that require an object as a parameter. One method is the Worksheet::Add method. The following sample code demonstrates passing a COleDispatchDriver as a parameter to the Worksheet::Add method. // Start Excel. _Application app; COleException e;  if(!app.CreateDispatch("Excel.Application", &e)) { char buf[80]; sprintf(buf, "Error on CreateDispatch: %ld (%08lx)", e.m_sc, e.m_sc); AfxMessageBox(buf, MB_SETFOREGROUND); return; }  // Make it visible. app.SetVisible(TRUE); // Add a workbook. COleVariant covOpt((long)DISP_E_PARAMNOTFOUND, VT_ERROR); Workbooks books(app.GetWorkbooks); _Workbook book(books.Add(covOpt)); // Get sheets collection of book1. Worksheets sheets(book.GetSheets); // Get a reference to sheet1. _Worksheet sheet1(sheets.GetItem(COleVariant((short)1))); // encapsulate sheet1 object in a VARIANT. VARIANT sheet1Var = {0}; sheet1Var.vt = VT_DISPATCH; sheet1Var.pdispVal = sheet1.m_lpDispatch; sheet1.m_lpDispatch->AddRef; // Add a sheet just after sheet1. Excel's Sheets.Add method // requires the 'After' parameter to be a sheet object, not // a sheet name or index. _Worksheet newSheet(sheets.Add(covOpt, sheet1Var, covOpt, covOpt)); AfxMessageBox("All done.", MB_SETFOREGROUND); // Cleanup. VariantClear(&sheet1Var); book.SetSaved(TRUE); app.Quit;

