question about introspection using inspect module

[Benjamin Rutt]

I'm trying to learn about introspection in Python.  my ultimate goal
is to be able to build a module "text database" of all modules that
are in the sys.path, by discovering all candidate modules (I've
already done that), importing all of them, and then introspecting on
each module to discover its functions, globals and classes.  But for
now I am having a problem with the latter.

I would like to import a module and figure out the names of its
defined functions, globals, and classes.  Here's my attempt, file
foo.py, which has a single function, class, and global defined:

    #!/usr/bin/env python

    def somefunction(i):
        i = i + 1

    class someclass:
        def __init__(self):
            self.x = 0
            self.y = 1

    someglobal = 1.2

    if __name__ == "__main__": # when run as a script
        import foo
        import inspect
        from inspect import *
        isfuncs = filter(lambda x: re.match("^is", x) and x, dir(inspect))
        print isfuncs
        print filter(lambda x: re.match("some", x[0]) and x[0], getmembers(foo))
        for f in isfuncs:
            exec('print "trying %20s: ",; print getmembers(foo, %s)' % (f, f))

the output of running it as a script is the following:

    ['isbuiltin', 'isclass', 'iscode', 'isdatadescriptor', 'isframe', 'isfunction', 'ismethod', 'ismethoddescriptor', 'ismodule', 'isroutine', 'istraceback']
    [('someclass', <class foo.someclass at 0x40058ddc>), ('somefunction', <function somefunction at 0x40066a74>), ('someglobal', 1.2)]
    trying            isbuiltin:  []
    trying              isclass:  [('someclass', <class foo.someclass at 0x40058ddc>)]
    trying               iscode:  []
    trying     isdatadescriptor:  []
    trying              isframe:  []
    trying           isfunction:  [('somefunction', <function somefunction at 0x40066a74>)]
    trying             ismethod:  []
    trying   ismethoddescriptor:  []
    trying             ismodule:  []
    trying            isroutine:  [('somefunction', <function somefunction at 0x40066a74>)]
    trying          istraceback:  []

I was trying to use inspect.getmembers(foo, <PRED>) with an
appropriate predicate ("is" function).  it looks like I am able to
discover that 'someclass' is a class, and that 'somefunction' is a
function (and also a routine, apparently).  However, I cannot seem to
discover that 'someglobal' is a global.  How to do so?  Thanks,
-- 
Benjamin Rutt