Excel automation: Close event missing

Question

Another hi all,

I am doing Excel automation via Interop in C#, and I want to be informed when a workbook is closed. However, there is no Close event on the workbook

Answer 1

I've created a hack using a polling-like approach, and it works:

Given the workbook to observe, I create a thread which periodically tries to find that workbook in the workbooks collection.

(The DisposableCom class is my current solution to properly cleanup COM objects.)

Excel.Application app = wbWorkbook.Application;
string sWorkbookName = wbWorkbook.Name;

Thread overseeWorkbooksThread = new Thread(new ThreadStart(
    delegate()
    {
        bool bOpened = false;

        Excel.Workbooks wbsWorkbooks = app.Workbooks;
        using (new DisposableCom(wbsWorkbooks))
        {
            while (true)
            {
                Thread.Sleep(1000);

                if (wbsWorkbooks.ContainsWorkbookProperly(sWorkbookName))
                    bOpened = true;
                else
                    if (bOpened)
                        // Workbook was open, so it has been closed.
                        break;
                    else
                    {
                        // Workbook simply not finished opening, do nothing
                    }
            }

            // Workbook closed
            RunTheCodeToBeRunAfterWorkbookIsClosed();
        }
    }));

overseeWorkbooksThread.Start();

The "ContainsWorkbookProperly" extension methods looks like this:

public static bool ContainsWorkbookProperly(this Excel.Workbooks excelWbs,
    string sWorkbookName)
{
    Excel.Workbook wbTemp = null;
    try
        wbTemp = excelWbs.Item(sWorkbookName);
    catch (Exception)
    {
        // ignore
    }

    if (wbTemp != null)
    {
        new DisposableCom(wbTemp).Dispose();
        return true;
    }

    return false;
}

Still I would be interested if there is a simpler or better solution.