use of calldll

[Piero]

I use the very good calldll module to interface to Windows DLL.

Now I have a problem with this type of function 'C 'prototype :

BOOL ReadOPCItem(HANDLE hConnect,HANDLE hGroup,HANDLE hItem,VARIANT
*pVar,FILETIME * pTimeStamp, DWORD quality)

I make this Python routine  :

def ReadOPCItem(self,hGroup,hItem):
	#~ ' May be used by an application to read the current value of an
item.
	#~ ' Is only valid if EnableDLLBuffering has been set to TRUE when
the
	#~ ' connection was established.
	#~ Public Type FileTime
	#~ dwLowDateTime As Long
	#~ dwHighDateTime As Long
	#~ End Type
	#~ Declare Function ReadOPCItem Lib "WTClient" Alias
"_ReadOPCItem at 24" (ByVal hConnect As Long, ByVal hGroup As Long, ByVal
hItem As Long, Var As Variant, pTimeStamp As FileTime, Quality As
Long) As Long
	ReadOPCItem =calldll.get_proc_address(self.opcclient,"_ReadOPCItem at 24")
		var_buf = calldll.membuf(8)
		filetime_buf = calldll.membuf(8)
		quality_buf = calldll.membuf(4)
		stato = calldll.call_foreign_function   (ReadOPCItem,'llllll', 'i',
			(self.handle,hGroup,hItem,var_buf.address(),filetime_buf.address(),quality_buf.address()))
		quality = struct.unpack ('l', quality_buf.read())
		value = struct.unpack ('bbbbbbb', var_buf.read())
		filetime = struct.unpack ('ll', filetime_buf.read())
		
		return stato,value,quality,filetime


Something can help on using VARIANT type in Python and CALLDLL

Thanks

Piero Dell'OSte