Is sys.exit equivalent to raise SystemExit?

问题

According to the documentation on sys.exit and SystemExit, it seems that

def sys.exit(return_value=None):  # or return_value=0
    raise SystemExit(return_value)

is that correct or does sys.exit do something else before?

回答1:

According to Python/sysmodule.c, raising SystemExit is all it does.

static PyObject *
sys_exit(PyObject *self, PyObject *args)
{
    PyObject *exit_code = 0;
    if (!PyArg_UnpackTuple(args, "exit", 0, 1, &exit_code))
        return NULL;
    /* Raise SystemExit so callers may catch it or clean up. */
    PyErr_SetObject(PyExc_SystemExit, exit_code);
    return NULL;
}

回答2:

As you can see at source code https://github.com/python-git/python/blob/715a6e5035bb21ac49382772076ec4c630d6e960/Python/sysmodule.c

static PyObject *
sys_exit(PyObject *self, PyObject *args)
{
    PyObject *exit_code = 0;
    if (!PyArg_UnpackTuple(args, "exit", 0, 1, &exit_code))
        return NULL;
    /* Raise SystemExit so callers may catch it or clean up. */
    PyErr_SetObject(PyExc_SystemExit, exit_code);
    return NULL;
}

it's only raise SystemExit and doesn't do anything else

回答3:

Yes, raising SystemExit and calling sys.exit are functionally equivalent. See sys module source.

The PyErr_SetObject function is how CPython implements the raising of a Python exception.

来源：https://stackoverflow.com/questions/36302165/is-sys-exit-equivalent-to-raise-systemexit