如何让ruamel.yaml识别NamedTuple为tuple以避免序列化报错？

以下是测试代码：

import sys
from typing import NamedTuple

import ruamel.yaml as ryaml


class Loc(NamedTuple):
    lat: float
    long: float


data = {
    "APAC": {
        "rating": 5,
        "leads": ["Jane", "John"],
        "locs": [Loc(1.0, 1.0), Loc(2.0, 2.0)],
    },
    "EMEA": {
        "rating": 5,
        "leads": ["Jane", "Jack"],
        "locs": [Loc(3.0, 3.0), Loc(4.0, 4.0)],
    }
}


def main():
    # 验证Loc实例确实是tuple子类
    assert all(map(lambda o: isinstance(o, tuple), data["APAC"]["locs"]))
    assert all(map(lambda o: isinstance(o, tuple), data["EMEA"]["locs"]))

    yml = ryaml.YAML()
    yml.register_class(Loc)
    yml.dump(data, sys.stdout)


if __name__ == '__main__':
    main()

执行后抛出如下错误：

File "C:\Repos\@Venv\myproj-cpy3.11-1\Lib\site-packages\ruamel\yaml\representer.py", line 1090, in represent_yaml_object
    anchor = state.pop(Anchor.attrib, None)
             ^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'pop'

直接使用原生tuple替代Loc()则无错误，环境为CPython 3.11 + ruamel.yaml==0.17.21。

方法一：自定义Representer，将Loc实例转为tuple序列化 #

不需要调用yml.register_class(Loc)，而是给Loc类添加自定义的序列化逻辑，让ruamel.yaml按tuple规则处理：

修改后的main函数：

def main():
    assert all(map(lambda o: isinstance(o, tuple), data["APAC"]["locs"]))
    assert all(map(lambda o: isinstance(o, tuple), data["EMEA"]["locs"]))

    yml = ryaml.YAML()
    
    # 自定义Loc的序列化逻辑，转为tuple处理
    def represent_loc(dumper, loc_instance):
        return dumper.represent_tuple(tuple(loc_instance))
    
    yml.representer.add_representer(Loc, represent_loc)
    yml.dump(data, sys.stdout)

方法二：给Loc类指定yaml_tag为tuple类型 #

直接在Loc类中添加yaml_tag属性，指定为!!python/tuple，ruamel.yaml会自动用tuple的序列化规则处理：

修改后的Loc类：

class Loc(NamedTuple):
    lat: float
    long: float
    yaml_tag = '!!python/tuple'

然后main函数中去掉yml.register_class(Loc)即可：

def main():
    assert all(map(lambda o: isinstance(o, tuple), data["APAC"]["locs"]))
    assert all(map(lambda o: isinstance(o, tuple), data["EMEA"]["locs"]))

    yml = ryaml.YAML()
    yml.dump(data, sys.stdout)

内容的提问来源于stack exchange，提问作者pepoluan