Hi,
I have been attempting to solve a problem with the reference counts of a COM object, preventing it from being freed. After more than a year I've discovered it only occurs when in the wxPython MainLoop(). I have included two files: main.py and itunes.py.
Here is the output from running the main.py with gui set to False:
OnAboutToPromptUserToQuitEvent
self.iTunes ref count: 2
self.Events ref count: 2
InterfaceCount: 0
GatewayCount: 0
With gui set to True, the following occurs:
OnAboutToPromptUserToQuitEvent
self.iTunes ref count: 2
self.Events ref count: 8
InterfaceCount: 1
GatewayCount: 3
OnCOMCallsDisabledEvent
OnCOMCallsEnabledEvent
OnQuittingEvent
OnCOMCallsDisabledEvent
The reference count does not decrease after the objects are deleted, and events are still dispatched. If the MainLoop() is used, the reference count of the COM object is retained when it is deleted. If anyone can offer any suggestions to reduce the reference count when wxPython is used I would be grateful.
Cheers,
Dave
main,py
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import itunes
import time
from wxPython.wx import *
wxID_TIMER = 1001
gui = False
class TaskBarApp(wxFrame):
def __init__(self, parent, id, title):
wxFrame.__init__(self, parent, id, title, size = (1,1), style=wxFRAME_NO_TASKBAR)
self.timer = wxTimer(self, wxID_TIMER)
self.Bind(EVT_TIMER, self.OnTimer, id=wxID_TIMER)
self.timer.Start(1000)
def OnTimer(self,event):
itunes.pumpevents()
class MyApp(wxApp):
def OnInit(self):
frame = TaskBarApp(None, -1, "MyApp")
frame.Center(wxBOTH)
frame.Show(false)
return true
if __name__ == "__main__":
itunes = itunes.iTunesConnection()
itunes.connect()
if gui:
app = MyApp(0)
app.MainLoop()
else:
while True:
itunes.pumpevents()
time.sleep(1)
itunes.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import pythoncom
import win32com.client
import gc
import sys
class iTunesConnection:
def __init__(self):
pass
def pumpevents(self):
pythoncom.PumpWaitingMessages()
if hasattr(self,"Events"):
if self.Events.quit:
self.cleanup()
def cleanup(self):
pythoncom.CoUninitialize()
pythoncom.CoFreeUnusedLibraries()
print "self.iTunes ref count: %s" % sys.getrefcount(self.iTunes)
print "self.Events ref count: %s" % sys.getrefcount(self.Events)
del self.Events
del self.iTunes
gc.collect()
print "InterfaceCount: %s" % pythoncom._GetInterfaceCount()
print "GatewayCount: %s" % pythoncom._GetGatewayCount()
def connect(self):
pythoncom.CoInitialize()
self.iTunes = win32com.client.dynamic.Dispatch("iTunes.Application")
self.Events = win32com.client.WithEvents(self.iTunes, iTunesEvents)
class iTunesEvents:
def __init__(self):
self.quit = False
def OnAboutToPromptUserToQuitEvent(self):
print "OnAboutToPromptUserToQuitEvent"
self.quit = True
def OnQuittingEvent(self):
print "OnQuittingEvent"
self.quit = True
def OnCOMCallsDisabledEvent(self,code):
print "OnCOMCallsDisabledEvent"
def OnCOMCallsEnabledEvent(self):
print "OnCOMCallsEnabledEvent"
def OnPlayerPlayEvent(self,track):
print "OnPlayerPlayEvent"
def OnPlayerStopEvent(self,track):
print "OnPlayerStopEvent"
def OnPlayerPlayingTrackChangedEvent(self,track):
print "OnPlayerPlayingTrackChangedEvent"