_tblib.py 文件源码

def _init():
    global _installed
    global tb_set_next
    if _installed:
        return

    _installed = True
    import platform
    try:
        if platform.python_implementation() == 'CPython':
            tb_set_next = _init_ugly_crap()
    except Exception as exc:
        sys.stderr.write("Failed to initialize cpython support: {!r}".format(exc))

    try:
        from __pypy__ import tproxy
    except ImportError:
        tproxy = None

    if not tb_set_next and not tproxy:
        raise ImportError("Cannot use tblib. Runtime not supported.")
    _import_dump_load()
    install()