Python Programming On Win32

Debugging COM Servers

At this point, we need to briefly explain how to debug a COM server. The theory behind this is covered in Chapter 12. It’s easy to use: just run the COM server script (comservers.py in our case) with the argument —debug: note the double hyphen. The output of any print statements in the server code can then be seen in the Trace Collector window on the PythonWin Tools menu.

Now it’s time to work with the form passed in from Visual Basic:

idForm = win32com.client.Dispatch(vbForm)

As before, you wrap the VB object using Dispatch:

# call a method we defined on the VB form
# arrays are converted automatically to Python tuples we can access
(width, height) = idForm.GetClientArea()
account = idForm.GetAccount()

The previous line is interesting for two reasons. First, you called a public method of the VB form you defined. This works in exactly the same way as calling methods of built-in VB objects. Second, you received back an array. Earlier we saw that a Python list or tuple can be passed to VB, where it’s interpreted as a variant array. The GetClientArea() method of our VB form returned a two-element variant array, which is received as a straightforward tuple. You can pass arrays easily in both directions. (Bear in mind that if VB returns an array containing strings, they are Unicode strings that must be tidied with the str function).

# access a built-in property of the VB form idForm.Caption = "Account " + account ############################################################# ...