[joshuamorton]

Ignore all of the validation aspects. In python, you have tuples, (x, y, z), then you have namedtuples and then attrs/dataclasses/pydantic-style shorthand classes.

These are useful even if only due to the "I can take the three related pieces of information I have and stick them next to each other". That is, if I have some object I'm modelling and it has more than a single attribute (a user with a name and age, or an event with a timestamp and message and optional error code), I have a nice way to model them.

Then, the important thing is that these are still classes, so you can start with

    @dataclass
    class User:
        name: str
        age: int

and have that evolve over time to

    @dataclass
    class User:
        name: str
        age: int
        ...
        permissions: PermissionSet
        
        @property
        def location():
            # send off an rpc, or query the database for some complex thing.

and since it's still just a class, it'll still work. It absolutely makes modelling the more complex cases easier too.

[lambdadmitry]

Note that that "location" property should be a method instead of property to signal that it does something potentially complex and slow. Making it a property practically guarantees that someone will use it in a loop without much second thought, and that's how you get N+1.

[joshuamorton]

Fair point! one of various @cached_property decorators might fix this, depending on the precise use case, but yeah this is an important consideration when defining your API.