[New-bugs-announce] [issue12894] pydoc help("modules keyword") is failing when a module throws an exception at the import time

[Christian S. Perone]

New submission from Christian S. Perone <christian.perone at gmail.com>:

Pydoc is failing when running the ModuleScanner().run() when you execute:

help("modules keyword")

... if some module throws an exception at the import time.
See this example:

>>> help("modules convolve")

Here is a list of matching modules.  Enter any module name to get more help.

numpy.numarray.convolve
scipy.fftpack.convolve
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python27\lib\site.py", line 467, in __call__
    return pydoc.help(*args, **kwds)
  File "C:\Python27\lib\pydoc.py", line 1727, in __call__
    self.help(request)
  File "C:\Python27\lib\pydoc.py", line 1768, in help
    self.listmodules(split(request)[1])
  File "C:\Python27\lib\pydoc.py", line 1873, in listmodules
    apropos(key)
  File "C:\Python27\lib\pydoc.py", line 1975, in apropos
    ModuleScanner().run(callback, key)
  File "C:\Python27\lib\pydoc.py", line 1938, in run
    for importer, modname, ispkg in pkgutil.walk_packages(onerror=onerror):
  File "C:\Python27\lib\pkgutil.py", line 125, in walk_packages
    for item in walk_packages(path, name+'.', onerror):
  File "C:\Python27\lib\pkgutil.py", line 125, in walk_packages
    for item in walk_packages(path, name+'.', onerror):
  File "C:\Python27\lib\pkgutil.py", line 125, in walk_packages
    for item in walk_packages(path, name+'.', onerror):
  File "C:\Python27\lib\pkgutil.py", line 125, in walk_packages
    for item in walk_packages(path, name+'.', onerror):
  File "C:\Python27\lib\pkgutil.py", line 110, in walk_packages
    __import__(name)
  File "C:\Python27\lib\site-packages\wx-2.8-msw-unicode\wx\lib\pubsub\core\arg1\__init__.py", line 16, in <module>
    raise RuntimeError(msg)
RuntimeError: Should not import this directly, used by pubsub.core if applicable

After suppressing the exception by changing the "apropos()" method inside the pydoc.py:

Line:
ModuleScanner().run(callback, key)

To:
ModuleScanner().run(callback, key, onerror=lambda error: error)

The problem is fixed, but I really don't know if this is the best way to suppress this and if we should suppress these exceptions, I think that as the intent of the help("modules keyword") is to find things with the keyword in the name, we shouldn't let the exception be propagated to the user.

----------
components: Library (Lib)
messages: 143502
nosy: Christian.S..Perone
priority: normal
severity: normal
status: open
title: pydoc help("modules keyword") is failing when a module throws an exception at the import time
type: behavior
versions: Python 2.6, Python 2.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue12894>
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