Skip to main content

Async Macro Example

We define a function that schedules a macro call to update the format of the calling range.

public static DateTime asyncFormatCaller()
object caller = XlCall.Excel(XlCall.xlfCaller);
if (caller is ExcelReference)
// Set the desired selection, then apply formatting
using (new ExcelSelectionHelper((ExcelReference)caller))
XlCall.Excel(XlCall.xlcFormatNumber, "h:mm:ss");
return DateTime.Now;

Above we use the following helper class to keep track of the current selection in a macro, so that the selection is correctly restored after the macro has completed.

// Helper class to deal with Excel selections in 'using' style
public class ExcelSelectionHelper : XlCall, IDisposable
object oldScreenUpdating;
object oldSelectionOnActiveSheet;
object oldActiveCellOnActiveSheet;

object oldSelectionOnRefSheet;
object oldActiveCellOnRefSheet;

public ExcelSelectionHelper(ExcelReference refToSelect)
oldScreenUpdating = Excel(xlfGetWorkspace, 40);
Excel(xlcEcho, false);

// Remember old selection state on the active sheet
oldSelectionOnActiveSheet = Excel(xlfSelection);
oldActiveCellOnActiveSheet = Excel(xlfActiveCell);

// Switch to the sheet we want to select
string refSheet = (string)Excel(xlSheetNm, refToSelect);
Excel(xlcWorkbookSelect, new object[]() { refSheet });

// record selection and active cell on the sheet we want to select
oldSelectionOnRefSheet = Excel(xlfSelection);
oldActiveCellOnRefSheet = Excel(xlfActiveCell);

// make the selection
Excel(xlcFormulaGoto, refToSelect);

public void Dispose()
Excel(xlcSelect, oldSelectionOnRefSheet, oldActiveCellOnRefSheet);

string oldActiveSheet = (string)Excel(xlSheetNm, oldSelectionOnActiveSheet);
Excel(xlcWorkbookSelect, new object[]() { oldActiveSheet });

Excel(xlcSelect, oldSelectionOnActiveSheet, oldActiveCellOnActiveSheet);

Excel(xlcEcho, oldScreenUpdating);

An improved function could first check whether the format of the caller needs to be updated before scheduling the macro call.