ipython debugger: full traceback on interactive pdb?

Question

I recently switched from ipython0.10 to ipython0.11. In ipython0.11, I only see a small snippet of the full traceback when the python debugger engages (i.e. using %pdb), whereas in ipython0.10 I'd see the full traceback. As far as I can tell, the full traceback is not directly accessible from the pdb command line - you can navigate through it with 'u' but can't see it directly.

So, is there any way to show the full traceback? Such as a configuration parameter?

Or, even more usefully, is there any way to have ipython just show the Exception that was caught, rather than showing where in the code it was caught?

EDIT: Example:

In [1]: pdb
Automatic pdb calling has been turned ON

In [2]: 1/0
> <ipython-input-2-05c9758a9c21>(1)<module>()
     -1 1/0

ipdb> q
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)
/Users/adam/<ipython-input-2-05c9758a9c21> in <module>()
----> 1 1/0

ZeroDivisionError: integer division or modulo by zero

I'd like to see the ZeroDivisionError before q'ing out of the pdb.

Answer 1

is there any way to have ipython just show the Exception that was caught, rather than showing where in the code it was caught?

You could use sys.excepthook:

import sys

def exc_hook(type, value, traceback):
    print type

sys.excepthook = exc_hook

From the sys module documentation:

sys.excepthook(type, value, traceback)

This function prints out a given traceback and exception to sys.stderr.

When an exception is raised and uncaught, the interpreter calls sys.excepthook with three arguments, the exception class, exception instance, and a traceback object. In an interactive session this happens just before control is returned to the prompt; in a Python program this happens just before the program exits. The handling of such top-level exceptions can be customized by assigning another three-argument function to sys.excepthook.

sys.__displayhook__
sys.__excepthook__

These objects contain the original values of displayhook and excepthook at the start of the program. They are saved so that displayhook and excepthook can be restored in case they happen to get replaced with broken objects.

---

You can also try starting ipython with the --xmode option set to Plain

From IPython reference:

$ ipython [options] files

--xmode=<modename>

Mode for exception reporting.

Valid modes: Plain, Context and Verbose.

Plain: similar to python’s normal traceback printing.

Context: prints 5 lines of context source code around each line in the traceback.

Verbose: similar to Context, but additionally prints the variables currently visible where the exception happened (shortening their strings if too long). This can potentially be very slow, if you happen to have a huge data structure whose string representation is complex to compute. Your computer may appear to freeze for a while with cpu usage at 100%. If this occurs, you can cancel the traceback with Ctrl-C (maybe hitting it more than once).

Here are some example usages. Notice the difference in lines for each traceback:

--xmode=Plain:

[ 19:55 jon@hozbox ~/SO/python ]$ ipython --xmode=Plain ipython-debugger-full-traceback-on-interactive-pdb.py 
------------------------------------------------------------
Traceback (most recent call last):
  File "ipython-debugger-full-traceback-on-interactive-pdb.py", line 2, in <module>
    1 / 0
ZeroDivisionError: integer division or modulo by zero

--xmode=Context:

[ 19:55 jon@hozbox ~/SO/python ]$ ipython --xmode=Context ipython-debugger-full-traceback-on-interactive-pdb.py 
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)

/home/jon/SO/python/ipython-debugger-full-traceback-on-interactive-pdb.py in <module>()
      1 
----> 2 #!/usr/bin/python
      3 1 / 0
      4 
      5 

ZeroDivisionError: integer division or modulo by zero

--xmode=Verbose:

[ 19:54 jon@hozbox ~/SO/python ]$ ipython --xmode=Verbose ipython-debugger-full-traceback-on-interactive-pdb.py 
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)

/home/jon/SO/python/ipython-debugger-full-traceback-on-interactive-pdb.py in <module>()
      1 
----> 2 #!/usr/bin/python
      3 1 / 0
      4 
      5 

ZeroDivisionError: integer division or modulo by zero

And without specifying a .py file:

--xmode=Plain:

[ 19:55 jon@hozbox ~/SO/python ]$ ipython --xmode=Plain

In [1]: 1 / 0
------------------------------------------------------------
Traceback (most recent call last):
  File "<ipython console>", line 1, in <module>
ZeroDivisionError: integer division or modulo by zero

--xmode=Context:

[ 20:03 jon@hozbox ~/SO/python ]$ ipython --xmode=Context

In [1]: 1 / 0
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)

/home/jon/SO/python/<ipython console> in <module>()

ZeroDivisionError: integer division or modulo by zero

--xmode=Verbose:

[ 20:01 jon@hozbox ~/SO/python ]$ ipython --xmode=Verbose


In [1]: 1 / 0
---------------------------------------------------------------------------
ZeroDivisionError                         Traceback (most recent call last)

/home/jon/SO/python/<ipython console> in <module>()

ZeroDivisionError: integer division or modulo by zero

---

Using the Python debugger.