Question

I’ve got the excelRTDserver.py up and running in Excel 2010 (32bit) by changing the EXCEL_TLB_MINOR value to 7. I can see the server in the add-ins list and if I enter =RTD("Python.RTD.TimeServer","","seconds","5") into a cell, I get the current time. But it never updates. If I change the “5” to another number, I get an update but after the initial change it never changes again.

How do I get it to update? I found someone else with a similar problem here, but no solution.

UPDATE: I’ve got a little further – there is an exception raised within ServerStart when casting the PyIDispatch callback object into a IRTDUpdateEvent callback object. Using this method to capture the error message, I get “Cannot create a file when that file already exists.”. If I follow the suggestion here and use win32com.client.CastTo(CallbackObject,'IRTDUpdateEvent') I get “This COM object can not automate the makepy process – please run makepy manually for this object”, but I have already run makepy for Microsoft Excel 12.0 Object Library (1.6).

Any help would be greatly appreciated.

Answer 1

I think you may be out of luck.

According to the author of excelRTDServer.py in a recent python-win32 thread:

^{The message that this is in response to describes your exact problem, and it’s recent, so maybe you already got this info directly, but in case you didn’t…}

I fear that things with IRTDUpdateEvent have changed with recent versions
of excel (since Excel 2007? I guess that’s not so ‘recent’ anymore…).

While hunting around for news of interface changes, I came across this
thread in a java forum:

http://www.nevaobject.com/phpbb3/viewtopic.php?t=516

The part that worries me is this comment:

“Apparently in Excel 12 (Excel 2007) the RTD callback object that
implements dual IRTDUpdateEvent interface throws exception (generic COM
exception 0x80020009) when is called via IDispatch. If you use v-table
binding the call to UpdateNotify succeeds. I don’t really know whether it
is a bug in Excel 12 or a feature.”

So far I haven’t been able to confirm this against the MSDN information…
But if this is true, it does explain the problem being seen. Many older
examples on the web, and pywin32+makepy treat this interface as IDispatch,
and wrap it accordingly.

I don’t think we can fix this with pywin32 as it is right now. My
understanding is that it relies on IDispatch support. May need to look at
comtypes (http://starship.python.net/crew/theller/comtypes/) to wrap the
(new?) IRTDUpdateEvent objects, or maybe a C extension. 🙁