python-3.x - 在运行时从字符串创建 namedtuple 实例(反射/动态创建)

Question

如何动态创建命名元组的实例？可能吗？

Msg = collections.namedtuple('Msg', 'a b c')
...
mymsg = Msg(a=1,b=2,c=3)
msg_as_dict = mymsg._asdict()
msg_as_dict['recover_name'] = type(mymsg).__name__

如何在运行时从 msg['recover_name'] 创建 Msg 实例？

更新:如何在运行时获取 namedtuple 的类型？意思是，从现有实例中获取“消息”。

Answer 1

这将在不需要反射的情况下工作:

def test_tuple_builder(self):
    from collections import namedtuple

    name = "Foo"
    attribs = "bar baz goo tar taz"
    values = [100, "Hello", -1, "World", "1968"]

    tpl_cls = namedtuple(name, attribs)
    foo = tpl_cls(*values)

    self.assertEqual(values[0], foo.bar)
    self.assertEqual(values[1], foo.baz)
    self.assertEqual(values[2], foo.goo)
    self.assertEqual(values[3], foo.tar)
    self.assertEqual(values[4], foo.taz)

    print("We always use '{baz}, {tar}' as an example.".format(baz=foo.baz, tar=foo.tar))

所有测试通过，输出:

We always use 'Hello, World' as an example.