build.py 文件源码

def __env(envdir):
    # http://stackoverflow.com/a/1883251
    if hasattr(sys, 'real_prefix'):
        # We're already inside someone else's virtualenv.
        return sys.prefix
    elif hasattr(sys, 'base_prefix') and sys.base_prefix != sys.prefix:
        # We're already inside someone else's pyvenv.
        return sys.prefix
    elif os.path.exists(envdir):
        # We've already built our own virtualenv.
        return envdir

    args = [sys.executable] + ENV_ARGS + [envdir]
    run(*args)
    return envdir