Earlier quoted context omitted.
well one appeal is that you dont have to write constructors, that‘s already enough of a win for me. then you get sane eq, and sane str, and already you remove 90% boilerplate
I really, genuinely don't get the appeal. I don't follow the "less code = better" ideology so maybe that's a contributor but I really don't see how this: class Person: def __init__(self, name, age): self.name = name self.age = age is any worse than this: @dataclass class Person: name: str age: int I'm not writing an eq method or a repr method in most cases, so it just doesn't add much for the cost.
> I'm not writing an eq method or a repr method in most cases, so it just doesn't add much for the cost.
That's part of the appeal. With vanilla classes, `__repr__`, `__eq__`, `__hash__` et. al. are each an independent, complex choice that you have to intentionally make every time. It's a lot of cognitive overhead. If you ignore it, the class might be fit for purpose for your immediate needs, but later when debugging, inspecting logs, etc, you will frequently have to incrementally add these features to your data structures, often in a haphazard way. Quick, what are the invariants you have to verify to ensure that your `__eq__`, `__ne__`, `__gt__`, `__le__`, `__lt__`, `__ge__` and `__hash__` methods are compatible with each other? How do you verify that an object is correctly usable as a hash key? The testing burden for all of this stuff is massive if you want to do it correctly, so most libraries that try to eventually add all these methods after the fact for easier debugging and REPL usage usually end up screwing it up in a few places and having a nasty backwards compatibility mess to clean up.
With `attrs`, not only do you get this stuff "for free" in a convenient way, you also get it implemented in a way which is very consistent, which is correct by default, and which also provides an API that allows you to do things like enumerate fields on your value types, serialize them in ways that are much more reliable and predictable than e.g. Pickle, emit schemas for interoperation with other programming languages, automatically provide documentation, provide type hints for IDEs, etc.
Fundamentally attrs is far less code for far more correct and useful behavior.