Getting call trace while executing "modules spam" at help prompt

[rishikesh]

BPO	7015
Nosy	@birkenfeld, @pitrou, @ned-deily, @merwok, @bitdancer
Superseder	bpo-7425: Improve the robustness of "pydoc -k" in the face of broken modules
Files	pkgutil.py.patch: pkgutil.py resistance against modules errors.

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2011-06-09.16:11:27.393>
created_at = <Date 2009-09-29.06:38:07.097>
labels = ['type-bug', 'library']
title = 'Getting call trace while executing "modules spam" at help prompt'
updated_at = <Date 2011-10-07.07:10:20.973>
user = 'https://bugs.python.org/rishikesh'

bugs.python.org fields:

activity = <Date 2011-10-07.07:10:20.973>
actor = 'ned.deily'
assignee = 'none'
closed = True
closed_date = <Date 2011-06-09.16:11:27.393>
closer = 'eric.araujo'
components = ['Library (Lib)']
creation = <Date 2009-09-29.06:38:07.097>
creator = 'rishikesh'
dependencies = []
files = ['15007']
hgrepos = []
issue_num = 7015
keywords = ['patch']
message_count = 7.0
messages = ['93253', '93282', '93361', '93366', '93377', '137999', '145059']
nosy_count = 7.0
nosy_names = ['georg.brandl', 'pitrou', 'ned.deily', 'eric.araujo', 'r.david.murray', 'rishikesh', 'jankratochvil']
pr_nums = []
priority = 'low'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '7425'
type = 'behavior'
url = 'https://bugs.python.org/issue7015'
versions = ['Python 2.6']

[rishikesh]

[root@ ~]# python
Python 2.6.2 (r262:71600, Aug 21 2009, 12:23:57) 
[GCC 4.4.1 20090818 (Red Hat 4.4.1-6)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> help()

Welcome to Python 2.6! This is the online help utility.

If this is your first time using Python, you should definitely check out
the tutorial on the Internet at http://docs.python.org/tutorial/.

Enter the name of any module, keyword, or topic to get help on writing
Python programs and using Python modules. To quit this help utility and
return to the interpreter, just type "quit".

To get a list of available modules, keywords, or topics, type "modules",
"keywords", or "topics". Each module also comes with a one-line summary
of what it does; to list the modules whose summaries contain a given word
such as "spam", type "modules spam".

help> modules spam

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

** (.:18352): WARNING **: Trying to register gtype 'WnckWindowState' as
flags when in fact it is of type 'GEnum'

** (.:18352): WARNING **: Trying to register gtype 'WnckWindowActions'
as flags when in fact it is of type 'GEnum'

** (.:18352): WARNING **: Trying to register gtype
'WnckWindowMoveResizeMask' as flags when in fact it is of type 'GEnum'
Adding pauses to default speech formatting strings.
Adding pauses to Gecko speech formatting strings.
Adding pauses to soffice speech formatting strings.
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python2.6/site.py", line 433, in __call__
    return pydoc.help(*args, **kwds)
  File "/usr/lib64/python2.6/pydoc.py", line 1720, in __call__
    self.interact()
  File "/usr/lib64/python2.6/pydoc.py", line 1738, in interact
    self.help(request)
  File "/usr/lib64/python2.6/pydoc.py", line 1757, in help
    self.listmodules(split(request)[1])
  File "/usr/lib64/python2.6/pydoc.py", line 1862, in listmodules
    apropos(key)
  File "/usr/lib64/python2.6/pydoc.py", line 1962, in apropos
    ModuleScanner().run(callback, key)
  File "/usr/lib64/python2.6/pydoc.py", line 1927, in run
    for importer, modname, ispkg in pkgutil.walk_packages(onerror=onerror):
  File "/usr/lib64/python2.6/pkgutil.py", line 110, in walk_packages
    __import__(name)
  File "/usr/lib/python2.6/site-packages/gdb/__init__.py", line 19, in
<module>
    import gdb.command.require
  File "/usr/lib/python2.6/site-packages/gdb/command/require.py", line
21, in <module>
    class RequireCommand (gdb.Command):
AttributeError: 'module' object has no attribute 'Command'
>>>

[pitrou]

It's a problem with one of your installed modules. I don't think Python
can do anything, unless you propose silencing all errors.

[jankratochvil]

This patch will make the modules' command succeeed. Later requesting the specific gdb' module will cause:

help> gdb
problem in gdb - <type 'exceptions.AttributeError'>: 'module' object has
no attribute 'Command'

I think this is right in general, a single broken module should not
abort the whole modules traversal.

Another issues is why the gdb' module fails: It expects the bindings inside the native /usr/bin/gdb' process to exist. Should it just
silently skip its functions if no /usr/bin/gdb' binding is found? Or should these gdb modules be located outside of /usr/lib*/python2.x'?
There are already some glue python modules
in `/usr/share/gdb/auto-load/'. Thanks for advice.

[bitdancer]

It may well be possible to improve the handling of exceptions (I haven't
looked at your patch yet), but fixing gdb, or rather the python bindings
for it, are out of the scope of this bug tracker since it is third-party
code.

[jankratochvil]

The python bindings were therefore fixed downstream:
gdb-6.8.91.20090930-2.fc12
http://koji.fedoraproject.org/koji/buildinfo?buildID=134595

[merwok]

Looks like this is an external bug.

[ned-deily]

The problem of pydoc apropos failing due to exceptions raised by pkgutil walk_packages is fixed in 2.7.3 by the changes for bpo-7425; they were already fixed in 3.x.