wxpython - passing arg to wx.app OnInit

[Stuart McGraw]

I have a wxPython app, conventionally structured
with a Application class derived from wx.App.
My problem is that the app accepts a command
line argument that must be acted upon within the
OnInit() method of the Application class.  How do
I pass it cleanly from main() into app.OnInit()?  In 
the simplified example below, dbfn is the piece of 
info that is in main() that OnInit() needs to use.
Is a global variable is the only way?  :-(

class Application (wx.App):
    def OnInit (self):
        oper = Operations (dbfn);
        frame = Frame (None, -1, "Title", oper)
        self.SetTopWindow (frame)
        return True

def main ():
    dbfn = sys.args[1]
    app = Application (redirect=0)
    app.MainLoop ()

Apologies if the answer is (or should be) obvious... this
is my first time using wxWindows and I am still rather new 
to Python.