wxPython: How do you start a wxPython application from a wxPython application? - python-2.7

Question

I am attempting to start a wxPython application but I want a banner to be displayed before it is started.
One way to do this is to start a wxPython application which in turn starts another wxPython application, the reason for doing it this way is since the App part of the second wxPython application needs to do some processing before starting and may take some time.
The issue is how do I start the other application and know that it has started?
Currently I do this which blocks for the entire GUI session:
subprocess.check_output(["python", "src/gui.py"], stderr=subprocess.STDOUT, shell=True)
I have attempted to do the following but the frame of the first application does not seem to close:
loadCompleted, EVT_LOAD_COMPLETED = wx.lib.newevent.NewEvent()
class MyRegion(wx.Frame):
def __init__(self, parent):
wx.Frame.__init__(self, parent, title="My Region")
self.label = wx.StaticText(self, label="Hello, World!")
sizer = wx.BoxSizer(wx.VERTICAL)
sizer.Add(self.label, 0, wx.ALL, 5)
self.SetSizer(sizer)
self.startThread = Thread(target=self.Start)
self.startThread.start()
self.Bind(EVT_LOAD_COMPLETED, self.OnClose)
def OnClose(self, result):
self.Close()
def Start(self):
try:
subprocess.check_output(["python", "src/gui.py"], stderr=subprocess.STDOUT, shell=True)
except:
pass
wx.PostEvent(self, loadCompleted(result=(None)))
if __name__ == "__main__":
app = wx.App()
frame = MyRegion(None)
frame.Show()
app.MainLoop()

Answer 1

I don't think starting a second wxPython application is the way to go. Instead, I would just load the banner inside your frame's __init__ method, then do your processing. When the processing finishes, you can destroy the banner and show your main app. Here's some psuedo-code:
#
class MyFrame(wx.Frame):
""""""
#----------------------------------------------------------------------
def __init__(self):
"""Constructor"""
wx.Frame.__init__(self, None, title="Test")
banner = MyBanner()
# do a bunch of stuff
banner.Destroy() # or banner.Close()
self.Show()
Now if the processing takes a really long time, you can put that into a thread and have the thread send a message back to the UI that tells it that the thread is finished. When the app receives the message, it can close the banner in the handler and show the App at that point. Please note that you need to use a thread-safe method, such as wx.CallAfter or wx.PostEvent.
Check out the following articles for ideas:
http://www.blog.pythonlibrary.org/2010/05/22/wxpython-and-threads/
http://www.blog.pythonlibrary.org/2013/09/05/wxpython-2-9-and-the-newer-pubsub-api-a-simple-tutorial/