The Weird and The Wonderful

public FileContentResult ExportToExcel(object datasource)
{
   var grid = new GridView();
   grid.DataSource = datasource;
   grid.DataBind();

   var sw = new StringWriter();
   var htw = new HtmlTextWriter(sw);

   grid.RenderControl(htw);

   byte[] excelFileBytesContent = this.Response.ContentEncoding.GetBytes(sw.ToString());
   var excelFileContentResult = new FileContentResult(excelFileBytesContent, "application/vnd.ms-excel");

   return excelFileContentResult;
}

void ReduceCandidates(OblongCollection candidateOblongs)
{
    for (int index = 0; index < candidateOblongs.Count; ++index)
    {
        Oblong fittedOblong = candidateOblongs[index].Reduce(); // <---------- Object Disposed exception here
        // <snip code that uses fittedOblong>
    }
}

void ReduceCandidates(OblongCollection candidateOblongs)
{
    for (int index = 0; index < candidateOblongs.Count; ++index)
    {
        using (Oblong currentCandidate = candidateOblongs[index])
        {
            Oblong fittedOblong = currentCandidate.Reduce();
            // <snip code that uses fittedOblong>
        }
    }
}