import imp, sys
#import string

def dynamically_load_module(name):
    if sys.modules.has_key(name):
        print name, "was already loaded!"
        return

    fp, filename, desc = imp.find_module(name)
    try:
        imp.acquire_lock()
        mod = imp.load_module(name, fp, filename, desc)
        imp.release_lock()
        print "Loaded: ", mod
    finally:
        if fp:
            fp.close()

print sys.modules.keys()
dynamically_load_module("string")
print sys.modules.keys()
print "sys.modules:", sys.modules["string"]
print string
# ^--- fails here with: 
#Traceback (most recent call last):
#  File "./idea9.py", line 23, in ?
#    print string
#NameError: name 'string' is not defined