site.py 文件源码

def force_global_eggs_after_local_site_packages():
    """
    Force easy_installed eggs in the global environment to get placed
    in sys.path after all packages inside the virtualenv.  This
    maintains the "least surprise" result that packages in the
    virtualenv always mask global packages, never the other way
    around.

    """
    egginsert = getattr(sys, '__egginsert', 0)
    for i, path in enumerate(sys.path):
        if i > egginsert and path.startswith(sys.prefix):
            egginsert = i
    sys.__egginsert = egginsert + 1