[PyChecker-list] Pychecker and ZODB, anyone?

[Greg W. <gw...@me...>]

Has anyone had any luck running Pychecker on a ZODB application?  The
problem, I suspect, is that ZODB does some evil magic at import time,
and that disagrees with Pychecker.  Actually, it disagrees with a lot of
tools, and I have learned that the usual solution is to manually
"import ZODB" before doing anything else.  With Pychecker, this didn't
help much.

Illustration: mems.lib.database is the heart of our application; in a
nutshell, everything in our system imports mems.lib.database, and
mems.lib.database imports almost nothing except ZODB.  So that seemed
like a logical place to start running pychecker, at least as long as
pychecker insists on checking code in modules other than the one you ask
it to check.

But things get hairy just pychecking mems.lib.database.  With my patch
#523136 applied to pychecker, I get this:

  $ pychecker mems.lib.database
  Processing mems.lib.database...
    Caught exception importing module mems.lib.database:
      File "/home/gward/bin/pychecker", line 422, in load()
        return self.initModule(self.setupMainCode())
      File "/home/gward/bin/pychecker", line 459, in setupMainCode()
        module = imp.load_module(self.moduleName, file, filename, smt)
      File "/www/mxpython/mems/lib/database.py", line 12
        from ZODB import DB
      File "lib.linux-i686-2.2/ZODB/__init__.py", line 32
    KeyError: ZODB

  Warnings...

  mems.lib.database:1: NOT PROCESSED UNABLE TO IMPORT

Here's a possibly-relevant snippet of ZODB/__init__.py, line numbers
courtesy of "cat -n":

    13  import sys, ExtensionClass, TimeStamp, cPersistence, Persistence
    14  import cStringIO, cPickle
    15  from zLOG import register_subsystem
    16  register_subsystem('ZODB')
    17
    18  # This is lame. Don't look. :(
    19  sys.modules['cPersistence']=cPersistence
    20
    21  Persistent=cPersistence.Persistent
    22
    23  # Install Persistent and PersistentMapping in Persistence
    24  if not hasattr(Persistence, 'Persistent'):
    25      Persistence.Persistent=Persistent
    26      Persistent.__module__='Persistence'
    27      Persistence.Overridable=cPersistence.Overridable
    28      Persistence.Overridable.__module__='Persistence'
    29      if not hasattr(Persistence, 'PersistentMapping'):
    30          import PersistentMapping
    31          sys.modules['PersistentMapping']=PersistentMapping
    32          sys.modules['BoboPOS']=sys.modules['ZODB']
                                                   ^^^^^^

It's pretty clear where the KeyError is coming from.  It's not clear why
it's happening: perhaps Pychecker's import fails to emulate Python's
exactly?  Ie. from the code, I presume that Python sets
sys.modules['ZODB'] before starting to execute the code in
ZODB/__init__.py, but Pychecker does not.  Is this correct?  If so,
would it be easy to fix?

Off for more investigating -- would appreciate any tips or hints!

        Greg
-- 
Greg Ward - software developer                gw...@me...
MEMS Exchange                            http://www.mems-exchange.org