Re: [Matplotlib-users] segfaults in ipython

[Fernando P. <Fer...@co...>]

John Hunter wrote:
> but in ipython I get the segfault
> 
>     peds-pc311:~> ipython
>     Python 2.4.1 (#2, Mar 30 2005, 21:51:10)
>     Type "copyright", "credits" or "license" for more information.
> 
>     IPython 0.6.16_cvs -- An enhanced Interactive Python.
>     ?       -> Introduction to IPython's features.
>     %magic  -> Information about IPython's 'magic' % functions.
>     help    -> Python's own help system.
>     object? -> Details about 'object'. ?object also works, ?? prints more.
> 
>     In [1]: from matplotlib.transforms import unit_bbox
> 
>     In [2]: b = unit_bbox()
> 
>     In [3]: b
>     Segmentation fault

This one is going to be hard to track, since I can't reproduce it on my system 
(Fedora 3):

planck[~]> ip
Python 2.3.4 (#1, Feb  2 2005, 12:11:53)
Type "copyright", "credits" or "license" for more information.

IPython 0.6.16_svn -- An enhanced Interactive Python.
?       -> Introduction to IPython's features.
%magic  -> Information about IPython's 'magic' % functions.
help    -> Python's own help system.
object? -> Details about 'object'. ?object also works, ?? prints more.

In [1]: from matplotlib.transforms import unit_bbox

In [2]: b = unit_bbox()

In [3]: b
Out[3]: <Bbox object at 0x965d6d4>

In [4]:

In [4]:
planck[~]> pylab

In [1]: from matplotlib.transforms import unit_bbox

In [2]: b = unit_bbox()

In [3]: b
Out[3]: <Bbox object at 0x893866c>

So neither plain ipython nor 'ipython -pylab' show me any sign of trouble here.

I'm afraid we'll have to debug this one by proxy, since I can't see any 
problem here.  The code which is executed when output is to be printed is the 
__call__ method of the CachedOutput object.  Look around line 476 in 
IPython/Prompts.py.  Adding some print/debug statements to that function might 
shed some light.

One thing you could try is toggling %Pprint back and forth.  This is the 
pretty printer used by ipython, which is part of the stdlib (module pprint). 
It might be triggering some problem in the underlying pycxx objects.

Cheers,

f