[Tutor] exception question

[Dave S]

Michael Janssen wrote:

>On Wed, 28 Apr 2004, Danny Yoo wrote:
>
>  
>
>>[Dave]
>>    
>>
>>>My problem is I do not know what the exception error will be. I have a
>>>script that will run 247, If an error occurs I want it to e-mail me with
>>>the exception error that caused the crash.
>>>      
>>>
>
>  
>
>>We can get a better stack trace out of the error by using the 'traceback'
>>module:
>>
>>    http://www.python.org/doc/lib/module-traceback.html
>>
>>So we can probably just trap all "Exception" things, and then use
>>traceback to extract more specific information out of the exception.
>>    
>>
>
>The traceback-module is the way to do it. Otherwise one will lose all this
>"line XX, in foo" information. Since traceback is somewhat complicated
>(too much slightly different functions to choose from) I feel like it's
>okey, when I post a more or less complete solution.
>
>Assuming you have done your best catching possible errors but you can't be
>shure which errors else might show up. The programm is running
>automatically or via web, so the printed traceback isn't of that much
>help.
>
>Then you put your "main" function (i.e. the function that contains all of
>your programm - it's allways good to organize your scripts that way)
>within a catchall try-except clause:
>
>
>if __name__ == "__main__":
>    try: main()
>    except:
>        import traceback, sys
>        tb_list = traceback.format_exception(*sys.exc_info())
>        body = "Script: %s\n" % sys.argv[0]
>        body += ''.join(tb_list)
>        mail(body, subject="Script Error", addr="Your address")
>        # give it back to console in case somebody is watching
>	raise
>
>
>Explanations:
>
>'if __name__ == "__main__"' is just a ward against running the code when
>*importing* the file as a module. It's nice to have when you ever want to
>import the script (to reuse its tricky functions). Has nothing to do with
>our topic ;-)
>
>"sys.exc_info()": this is where the traceback-object comes from. There is
>a warning on http://www.python.org/doc/lib/module-sys.html about problems
>with garbage collection. Nevertheless above code should be save (at least
>because the programm will terminate soon ;-).
>
>"*sys.exc_info()": sys.exc_info returns a tuple. "*" unfolds the tuple as
>arguments to format_exception. This special syntax is described in:
>http://docs.python.org/tut/  Section 4.7.4
>
>traceback.format_exception: from all those functions from the
>traceback-module this seems proper to me.
>
>"mail": I hope you got your own mail-function? Use smtplib.
>
>
>The result looks very much like a traceback as written to console. Adding
>the hostname into the mail might be a good idea (with socket.gethostname).
>
>
>Michael
>
>_______________________________________________
>Tutor maillist  -  Tutor at python.org
>http://mail.python.org/mailman/listinfo/tutor
>
>
>  
>
This is invaluable stuff. Thank you so much for taking the time to explain.
You have given me some new ideas - and explained the

 __name__ == "__main__"

thing !

Cheers again

Dave

 :-)  :-)  :-)  :-)