ADO Events with win32com

[Paul Moore]

On 25 Jul 2001 12:59:44 -0700, nmack at pacbell.net (angusm) wrote:
>You might want to wait for a more convincing explanation from someone
>else but I was able to duplicate the problem and the code below worked
>for me...it ain't pretty :-).

Thank you, thank you, thank you! It's perfectly clear now. Your code may not be
pretty, but it gave me all the pointers I needed...

>I encountered two problems based on your code:
>1)It appears the event class sees a different 'finished' variable from
>what you define in your module.

Doh! Yes, Python treats any variable which gets assigned to in a function as
local unless it's explicitly declared using 'global'. If I could actually write
code in Python, I'd be dangerous :-)

>2)adAsyncConnect doesn't seem to work because the infinite loop that
>gets created to wait for the events hogs the entire thread. There is
>no way for the dispatched event to break in asynchronously...

Again, I probably should have known this. In order to get COM events, the
application must pump the Windows message loop. Your solution works fine for me,
but there's also a win32gui.PumpWaitingMessages() call which just services any
waiting messages. You can just put a call to this inside the wait loop (which,
of course, would be doing real work if this was a proper application...)

>hope this helps,
>Angus

It does. Thanks for your help. FWIW, the following is a working version of my
code:

from win32com.client import DispatchWithEvents, constants
import win32gui

finished = 0

class ADOEvents:
    def OnWillConnect(*args):
        pass
    def OnConnectComplete(*args):
        print `args`
        global finished
        finished = 1

def Test():
    Conn = DispatchWithEvents("ADODB.Connection", ADOEvents)
    ConnStr = "Provider=msdaora;Prompt=complete"
    Conn.Open(ConnStr, Options=constants.adAsyncConnect)
    while not finished:
        win32gui.PumpWaitingMessages()
        print '...'
        pass

if __name__ == '__main__':
    Test()

Paul