[Pythonmac-SIG] wxPython -- getting Traceback on errors (was: some disappointment using it.)

[Louis Pecora]

Charles Hartman wrote:
> It occurs to me that if you added an OnExit() handler to your app -- 
> any app that's giving quit-too-soon trouble. The handler could simply 
> put up a wx.MessageBox, which gets an OK from the user. This would 
> pause the app on the way out, and therefore permit the normal app 
> output window (without changing redirection) to stay onscreen as long 
> as one liked. A little baroque, but pretty easy.
>
> Charles Hartman 

I think I've found the right circumstances in which getting Traceback works.

I tried what you said above, but it didn't work, although I did get the 
code to work by providing more path info.  Below is the App portion of 
the code (the hello.py example 3 in the book Chap.1).  I get the code to 
work now so long as I have the full path to the graphic image.  If I 
make an error in the path, the app exits (as it should, I would guess).  
The OnExit is not invoked if there is an error.  Here are the 
circumstances in which it is invoked or not (I tried to put this in a 
logical order) :

(1) __init__ (and hence, wx.App.__init__) are not called (both commented 
out)
          (a)   path is wrong, error     NO OnExit
          (b)   path is right, no error  NO OnExit

(2) __init__ (and hence, wx.App.__init__) are both called as shown below
          (a) redirect= True
                (i)  path is wrong  NO OnExit  , but output is in 
external file
                (ii) path is right  YES OnExit , and output is in 
external file

          (b) redirect= False
                (i)  path is wrong  NO OnExit , but output is to 
Terminal with traceback (!)
                (ii) path is right  YES OnExit, and output is to Terminal

Bottom line:  OnExit is only invoked if the program runs without error.  
If you want the traceback you have to include a call to wx.App.__init__ 
and set the type of redirect you want.  Note that redirect to the 
Terminal works fine then and the whole Traceback appears as one would 
like. A good hint for newbies like me.


App portion of my code:

class App(wx.App):
    """Application Class;"""
   
    def __init__(self):
        wx.App.__init__(self,redirect=True, 
filename="/Users/louispecora/Desktop/Hello.out")
   
    def OnInit(self):
        print "***here"
        
image=wx.Image('/Users/louispecora/Code/python/test_folder/wxPython_learn/rappin_cover150.jpg',
            wx.BITMAP_TYPE_JPEG)
        self.frame = Frame(image)
        self.frame.Show()
        self.SetTopWindow(self.frame)
        return True
       
    def OnExit(self):
        print "In OnExit()"
        retCode=wx.MessageBox("Quit?", caption="Message on Quit.")



-- 
Cheers,

Lou Pecora

Code 6362
Naval Research Lab
Washington, DC  20375
USA
Ph:  +202-767-6002
email:  pecora at anvil.nrl.navy.mil