When to Marshall.Release

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When to Marshall.Release
Release object out of function called? 
dan gallery




Posts: 83
 Joined: 2009-10-19
Hi guys, please consider the following code. Should getCellText(Excel.Range rng) perform a Marshal.Release of the com object variable that was passed in? Or should only the calling program do the Marshal.release?

Thanks,
Dan


public void parentCode() {

Excel.Application excelApp = new Excel.ApplicationClass();
Excel.Workbook aWorkbook = excelApp .Application.Workbooks.Open("someFile.xls"...);
Excel.Range rng = (Excel.Range) aWorkbook.ActiveSheet.get_Range("A1", "A1");

string cellText = getCellText(rng);

if (excelApp != null) Marshal.ReleaseComObject(excelApp);
if (aWorkbook != null) Marshal.ReleaseComObject(aWorkbook );
if (rng!= null) Marshal.ReleaseComObject(rng);
}

private string getCellText(Excel.Range rng) {

string cellText = "";
try {
cellText = rng.Value.ToString();
}
catch (Exception){}

// should I do this???
if (rng!= null) Marshal.ReleaseComObject(rng);

return cellText;

} [CODE]
Posted 17 Jan, 2012 12:50:09 Top
Andrei Smolin


Add-in Express team


Posts: 18821
 Joined: 2006-05-11
Hi Dan,

You should decide for yourself which of the procedures you prefer to release that COM object. I always use the approach "the caller is responsible for releasing a COM object that was passed in", in other words I'd comment out that line in getCellText.

Note that the parentCode method creates and leaves unreleased two COM objects:
- excelApp.Workbooks
- aWorkbook.ActiveSheet


Andrei Smolin
Add-in Express Team Leader
Posted 18 Jan, 2012 03:11:07 Top
dan gallery




Posts: 83
 Joined: 2009-10-19
Thanks Andrei, that's what I thought. And yes, right you are about the 2 unreleased variables.

Dan
Posted 18 Jan, 2012 20:46:14 Top