[IPython-user] interactive help question

[Fernando Perez]

Arnd Baecker wrote:

> When I do the following on a "normal" python prompt
> ##############
> def add_xy(x,y):
>     """return sum of x and y
>     """
>     return(x+y)
> 
> help(add_xy)
> ##############
> 
> I get the expected help.
> However for Ipython I end up with a KeyError.

No, it's not an ipython thing.  Check the behavior with a _clean_ python vs 
ipython session, where you have just started.  I did a bunch of tests, and the 
problem is actually caused by scipy.  What I found is that, if I am in a 
session where scipy has been previously brougth in via @run, or in python via 
'from foo import *', where foo.py has an 'import scipy', then the kind of 
help() call you show indeed fails.  I have seen both the error you mention and 
a different one.

Here is an example, from a _plain_ python shell, not ipython:

 >>> from Operator import *  # Operator.py does an 'import scipy'
 >>> def foo():
...     'a docstring'
...     pass
...
 >>> help(foo)
Traceback (most recent call last):
   File "<stdin>", line 1, in ?
   File "/usr/lib/python2.2/site-packages/scipy_base/ppimport.py", line 258, 
in __call__
     return _pydoc.help(*new_args, **kwds)
   File "/usr/lib/python2.2/pydoc.py", line 1510, in __call__
     self.help(request)
   File "/usr/lib/python2.2/pydoc.py", line 1546, in help
     else: doc(request, 'Help on %s:')
   File "/usr/lib/python2.2/pydoc.py", line 1338, in doc
     module = inspect.getmodule(object)
   File "/usr/lib/python2.2/inspect.py", line 363, in getmodule
     modulesbyfile[getabsfile(module)] = module.__name__
   File "/usr/lib/python2.2/inspect.py", line 344, in getabsfile
     return os.path.normcase(
   File "/usr/lib/python2.2/inspect.py", line 329, in getsourcefile
     filename = getfile(object)
   File "/usr/lib/python2.2/site-packages/scipy_base/ppimport.py", line 268, 
in _inspect_getfile
     object = object._ppimport_module
   File "/usr/lib/python2.2/site-packages/scipy_base/ppimport.py", line 222, 
in __getattr__
     module = self._ppimport_importer()
   File "/usr/lib/python2.2/site-packages/scipy_base/ppimport.py", line 200, 
in _ppimport_importer
     module = __import__(name,None,None,['*'])
   File "/usr/lib/python2.2/site-packages/scipy/xplt/__init__.py", line 47, in ?
     from Mplot import *
   File "/usr/lib/python2.2/site-packages/scipy/xplt/Mplot.py", line 46, in ?
     _user_path = _getdir()
   File "/usr/lib/python2.2/site-packages/scipy/xplt/Mplot.py", line 41, in 
_getdir
     if not weave.catalog.is_writable(path):
   File "/usr/lib/python2.2/site-packages/scipy_base/ppimport.py", line 223, 
in __getattr__
     return getattr(module, name)
AttributeError: 'module' object has no attribute 'catalog'


So in this case, blame scipy's ppimport magic for breaking the help system, 
not my poor ipython :)

Cheers,

f