Subclassing built in types

[davetapley]

This currently doesn't work:

class Id(str):
    def __repr__(self) -> str:
        return 'ID  ' + self

@dataclass
class Config:
    id: Id

If I to_yaml(Config(id=Id('b'))) I get:

yaml.representer.RepresenterError: ('cannot represent an object', 'b')

and when I from_yaml I get back a str, not an Id:

config = from_yaml(Config, '''
id: b
''')

print(config.id) # is just 'b', not 'ID b'

---

My use case for this is that I want to:

a. Add extra methods on to Id

b. Support multiple ID types via a union, and have serde select the correct one, e.g.:

class SingleId(str):
    def __repr__(self) -> str:
        return 'ID  ' + self

class DoubleId(list[str]):
    def __repr__(self) -> str:
        return 'ID  ' + '/'.join(self)

@dataclass
@serde(tagging=Untagged)
class Config:
    id: SingleId | DoubleId

c1 = Config(id=SingleId('a'))
c2 = Config(id=DoubleId([ 'a', 'b' ]))

print(c1)
print(c2)

c3 = from_yaml(Config, '''
id: a
''')
print(c3)

c4 = from_yaml(Config, '''
id: [ a, b ]
''')
print(c4)

which currently fails with:

serde.compat.SerdeError: Can not deserialize 'a' of type str into Union[SingleId, DoubleId].
Reasons:
 Failed to deserialize into SingleId: name 'SingleId' is not defined
 Failed to deserialize into DoubleId: Unsupported type: str

---

I can work around for now, by just using the built in types and then casting after, but it would be great if supported by serde.
Thoughts?