__init__.py 文件源码

def cache_py2_modules():
    """
    Currently this function is unneeded, as we are not attempting to provide import hooks
    for modules with ambiguous names: email, urllib, pickle.
    """
    if len(sys.py2_modules) != 0:
        return
    assert not detect_hooks()
    import urllib
    sys.py2_modules['urllib'] = urllib

    import email
    sys.py2_modules['email'] = email

    import pickle
    sys.py2_modules['pickle'] = pickle

    # Not all Python installations have test module. (Anaconda doesn't, for example.)
    # try:
    #     import test
    # except ImportError:
    #     sys.py2_modules['test'] = None
    # sys.py2_modules['test'] = test

    # import dbm
    # sys.py2_modules['dbm'] = dbm