Question

I am making a wxpython app that needs to have internet connection as a must . So , i need to check if connection is present , and if not , then do an exit . So my code looks like this .

class Example(wx.Frame):

    def __init__(self, parent, title):
        super(Example, self).__init__(parent, title=title, 
            size=(700,650))
        self.InitUI()
        self.Centre()

#*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.
#--------------------------------------------------------------------------------

        favicon = wx.Icon(ICON_PATH, wx.BITMAP_TYPE_ICO)
        wx.Frame.SetIcon(self, favicon)
        self.Show()     

    def InitUI(self):
        #checkConnection()
        checkInstances()

        panel = wx.Panel(self)

        font = wx.SystemSettings_GetFont(wx.SYS_SYSTEM_FONT)
        font.SetPointSize(9)

        font1 = wx.SystemSettings_GetFont(wx.SYS_SYSTEM_FONT)
        font1.SetPointSize(10)

#Layout 

        vbox = wx.BoxSizer(wx.VERTICAL)

        hbox1 = wx.BoxSizer(wx.HORIZONTAL)
        st1 = wx.StaticText(panel, label='Select Slot :')
        st1.SetFont(font1)
        hbox1.Add(st1, flag=wx.ALL, border=8)

        try:
            handler = urllib.urlopen("http://%s/api/get-slots/?api_key=%s"%(BASE_DOMAIN, API_KEY))
        except:

            wx.MessageBox("Error communicating with the server.", 'WARNING',wx.OK |wx.ICON_INFORMATION)
            handler = None
            sys.exit(0)

So i want to check for that link above (some link) , and if it fails , i display a message box , and then I exit . When i run this (with internet off) , the app does shows the message , and after clicking OK , another traceback box opens with a print

SystemExit:0

It does not actually exit . Tried using self.Close also . That does’nt work too .
Thought of making a checkconnection function as soon as we run the app .

def checkConnection():

    try:
        test = urllib.urlopen("http://www.google.com")
    except:
        sys.exit(0)

Placed it at

 def InitUI(self):
        checkConnection()
        .........
        .........

This also did the same thing . So is there some way to avoid the printing
and ACTUALLY EXIT?

os._exit worked but I just thought that sys.exit should have worked too .
So any hints guys?

Answer 1

Instead of sys.exit (or os._exit) use

self.Destroy()

os._exit halts the process abruptly without calling any cleanup handlers and should generally not be used (except to halt child processes after a fork).

sys.exit raises a SystemExit exception. wxpython must be catching this exception and choosing to print the error message without quitting the app.

self.Destroy() should quit the app.

---

try:
    test = urllib.urlopen("http://www.google.com")
except IOError:
    wx.MessageBox("Error communicating with the server.")
    self.Destroy()