[Sugar-devel] [DESIGN] SL Bug# 2063 : Sugar should bring up an alert when an unhandled Python exception occurs

Mukul Gupta mukul at seeta.in
Mon Oct 25 14:29:10 EDT 2010


Wish to have your feedback on the design aspect of the ticket 2063 (Sugar
should bring up an alert when an unhandled Python exception occurs) - please
find the git diff attached below. This is an attempt to display an alert
when an unhandled Python exception occurs in the journal. Unfortunately,
when the exception takes place in journalactivity.py , I am neither unable
to notice the Journal Icon (it disappears),

Please find my explanations on the code added as comments.

diff --git a/journalactivity.py b/journalactivity.py
index 44cc018..36a2e2e 100644
--- a/journalactivity.py
+++ b/journalactivity.py
@@ -358,8 +358,20 @@ class JournalActivity(Window):

''' Defining an Error Alert function in the Journal Activity Class which
displays the message as

Operation could not be performed
Please check the logviewer activity for details
and an OK button

+    def uncaught_exception_alert(self):
+        alert = ErrorAlert(title="Operation could not be performed",
msg="Please check the logviewer activity for details ")
+    alert.connect('response', self.__alert_response_cb)
+    self.add_alert(alert)
+    alert.show()
 _journal = None

Defining a function which logs the unhandled exception as well as calls the
Error Alert in the Journal whenever any uncaught exception occurs

+def _alert_excepthook(exc_type, exc_value, traceback):
+    logging.exception('Unhandled Python exception: %s', repr((exc_type,
exc_value, traceback)))
+    _journal.uncaught_exception_alert()
When an exception is raised and uncaught, sys.excepthook is called with
three arguments, the exception class, exception instance, and a traceback
object.The function _alert_excepthook is called only when an unhandled
exception occurs.
+sys.excepthook = _alert_excepthook
 def get_journal():
     global _journal
     if _journal is None:

I wish to request you to please review the code and suggest desired changes,
if any.

Moreover, I have two important questions regarding the bug.

1. To catch all unhandled python exceptions in sugar, where exactly should
we be looking forward to be the venue for adding the functionality?

    Adding it in journalactivity.py doesn't seem to serve all purposes. It
has to be added somewhere which is being used all the time.

2. Wish if you could recommend on the GUI feature that could be used for
displaying the alert message to the user.

Looking forward to for your valuable suggestions,


Mukul Gupta
Research Engineer,SEETA
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