Wincom and Excel example

This example puts "foo" in the first row of the 1st column of an Excel Sheet.

DEFINE xlapp INTEGER
DEFINE xlwb INTEGER
MAIN
  DEFINE result INTEGER
  DEFINE str STRING
--initialization of global variables
  LET xlapp = -1
  LET xlwb = -1
--first, we must create an Instance of an Excel Application
  CALL ui.Interface.frontCall("WinCOM", "CreateInstance",
  ["Excel.Application"], [xlapp])
  CALL CheckError(xlapp, __LINE__)
--then adding a Workbook to the current document
  CALL ui.interface.frontCall("WinCOM", "CallMethod",
  [xlapp, "WorkBooks.Add"], [xlwb])
  CALL CheckError(xlwb, __LINE__)
--then, setting it to be visible
  CALL ui.interface.frontCall("WinCOM", "SetProperty",
  [xlapp, "Visible", true], [result])
  CALL CheckError(result, __LINE__)
--then CALL SetProperty to set the value of the cell
  CALL ui.Interface.frontCall("WinCOM", "SetProperty", 
  [xlwb, 'activesheet.Range("A1").Value', "foo"],[result])
  CALL CheckError(result, __LINE__)
--then CALL GetProperty to check the value again
  CALL ui.Interface.frontCall("WinCOM", "GetProperty",
  [xlwb, 'activesheet.Range("A1").Value'], [str])
  CALL CheckError(str, __LINE__)
  DISPLAY "content of the cell is: " || str

 --then Free the memory on the client side
  CALL freeMemory()
END MAIN

FUNCTION freeMemory()
 DEFINE res INTEGER
  IF xlwb != -1 THEN
    CALL ui.Interface.frontCall("WinCOM","ReleaseInstance", [xlwb], [res] )
  END IF
  IF xlapp != -1 THEN
    CALL ui.Interface.frontCall("WinCOM","ReleaseInstance", [xlapp], [res] )
  END IF
END FUNCTION

FUNCTION checkError(res, lin)
  DEFINE res INTEGER
  DEFINE lin INTEGER
  DEFINE mess STRING
  IF res = -1 THEN
    DISPLAY "COM Error for call at line:", lin
    CALL ui.Interface.frontCall("WinCOM","GetError",[],[mess])
    DISPLAY mess
--let's release the memory on the GDC side
    CALL freeMemory()
    DISPLAY "Exit with COM Error."
    EXIT PROGRAM (-1)
  END IF
END FUNCTION