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Title: code.InteractiveConsole ignores sys.excepthook
Type: behavior Stage: resolved
Components: Library (Lib) Versions: Python 3.3
Status: closed Resolution: fixed
Dependencies: Superseder:
Assigned To: Nosy List: aliles, asvetlov, berker.peksag, flox, ncoghlan, pitrou, python-dev, vstinner
Priority: normal Keywords: patch

Created on 2011-07-27 12:10 by aliles, last changed 2022-04-11 14:57 by admin. This issue is now closed.

File name Uploaded Description Edit aliles, 2011-07-27 12:10 Demonstrate sys.excepthook behaviour from code.InteractiveConsole aliles, 2011-07-27 12:56
issue12643.diff aliles, 2012-08-20 08:11 Add unit tests. Call sys.excepthook if overridden review
issue12643_2.diff aliles, 2012-08-20 12:32 Updated patch to address feedback review
Messages (14)
msg141222 - (view) Author: Aaron Iles (aliles) * Date: 2011-07-27 12:10
code.InteractiveConsole doesn't match the CPython interactive interpreter with respect to allowing sys.excepthook to handle exceptions. Unlike the interactive interpreter, replacing sys.excepthook with an alternate function will not change exception handling behaviour from inside a code.InteractiveConole

This affects downstream interpreters such as PyPy.
msg141224 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2011-07-27 12:29
What do you suggest?
msg141225 - (view) Author: Aaron Iles (aliles) * Date: 2011-07-27 12:43
OK. Not something I was expecting to be asked. But cool :D

If it's not possible for InteractiveConsole to allow exceptions to propagate through sys.excepthook. (I assume they are being caught in a try: catch: block) check sys.excepthook for a custom exception handler and call present.

As InteractiveConsole is supposed to "Closely emulate the behaviour of the interactive Python interpreter", any existing code that replies on it's current could be viewed as relying on a bug.

I'd be happy to attempt a patch if it's worthwhile preparing one.
msg141226 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2011-07-27 12:48
> If it's not possible for InteractiveConsole to allow exceptions
> to propagate through sys.excepthook.

Ok, I was not sure that I understood correctly. This change should be an option to not break existing code.
msg141227 - (view) Author: Aaron Iles (aliles) * Date: 2011-07-27 12:56
Yes. I have code that behaves differently under CPython and PyPy because of this issue.

Admittedly that code is somewhat evil. It's attached for reference, in particular the __HelpSyntax class.
msg141367 - (view) Author: Antoine Pitrou (pitrou) * (Python committer) Date: 2011-07-29 13:10
If someone is setting sys.excepthook, they are not expecting it to be ignored, so I think there's no reason to preserve existing behaviour. On the other hand, it is easy to customize exception printout by subclassing InteractiveConsole and overriding the showtraceback() method.

aliles, if you want to work on a patch, we have a developer's guide at
msg141369 - (view) Author: Antoine Pitrou (pitrou) * (Python committer) Date: 2011-07-29 13:11
Another possibility yet is to add an "excepthook" argument to the InteractiveInterpreter / InteractiveConsole constructors.
msg168635 - (view) Author: Aaron Iles (aliles) * Date: 2012-08-20 08:11
Submitted patch. Patch creates a new unit test suite with basic unit tests for InteractiveConsole. Enhances InteractiveConsole to call sys.excepthook instead of it's own handler if the user has overridden the excepthook.

The unit tests use the new unittest.mock module and ExitStack class for contextlib.
msg168652 - (view) Author: Aaron Iles (aliles) * Date: 2012-08-20 12:32
New patch to address comments provide by Nick Coghlan in person at PyCon-AU 2012.
msg168656 - (view) Author: Roundup Robot (python-dev) (Python triager) Date: 2012-08-20 13:02
New changeset a812de69b493 by Nick Coghlan in branch 'default':
Issue #12643: Respect sys.excepthook in code.InteractiveConsole
msg168662 - (view) Author: Andrew Svetlov (asvetlov) * (Python committer) Date: 2012-08-20 14:39
Is it finished or not?
Also looks like patch applied to 3.3 while issue marked for 2.7 and 3.2 also.
msg168665 - (view) Author: Nick Coghlan (ncoghlan) * (Python committer) Date: 2012-08-20 14:50
The patch also adds a test suite for the code module, in order to demonstrate that the issue is actually fixed.

However, due to the interactive nature of the component, the new tests rely on unittest.mock. Backporting the test suite would mean eliminating that dependency (which is doable, but somewhat tedious).

So we can either leave the issue open, indicating that a backport of the tests and change to 2.7 (and perhaps 3.2) is still acceptable, or else declare that we aren't going to worry about that and just leave this as something that is only supported properly in 3.3+
msg168666 - (view) Author: Andrew Svetlov (asvetlov) * (Python committer) Date: 2012-08-20 14:58
I'm ok with current status.
Thanks for clarification.
msg275909 - (view) Author: Berker Peksag (berker.peksag) * (Python committer) Date: 2016-09-12 01:49
3.2 is now dead and it's probably not worth to backport tests to 2.7 in 2016 :) Closing this as 'fixed'.
Date User Action Args
2022-04-11 14:57:20adminsetgithub: 56852
2016-09-12 01:49:27berker.peksagsetstatus: open -> closed

versions: + Python 3.3, - Python 2.7, Python 3.2
nosy: + berker.peksag

messages: + msg275909
resolution: fixed
stage: needs patch -> resolved
2012-08-20 14:58:29asvetlovsetmessages: + msg168666
2012-08-20 14:50:02ncoghlansetmessages: + msg168665
versions: - Python 3.3
2012-08-20 14:39:05asvetlovsetmessages: + msg168662
2012-08-20 13:02:43python-devsetnosy: + python-dev
messages: + msg168656
2012-08-20 12:32:31alilessetfiles: + issue12643_2.diff

messages: + msg168652
2012-08-20 10:36:53asvetlovsetnosy: + asvetlov
2012-08-20 08:11:46alilessetfiles: + issue12643.diff

nosy: + ncoghlan
messages: + msg168635

keywords: + patch
2012-03-28 17:19:25floxsetnosy: + flox
2011-07-29 13:11:44pitrousetmessages: + msg141369
2011-07-29 13:10:06pitrousetversions: + Python 3.3
nosy: + pitrou

messages: + msg141367

stage: needs patch
2011-07-27 12:56:38alilessetfiles: +

messages: + msg141227
2011-07-27 12:48:15vstinnersetmessages: + msg141226
2011-07-27 12:43:29alilessetmessages: + msg141225
2011-07-27 12:29:45vstinnersetnosy: + vstinner
messages: + msg141224
2011-07-27 12:10:06alilescreate