Support for attrs dataclasses

[bilelomrani1]

attrs is a popular third-party package for defining dataclasses with additional convenient features (converters, more fine-grained initialization, etc.). Currently simple-parsing only supports native dataclasses, is there any interest to support attrs dataclasses as well?

[lebrice]

Hello there @bilelomrani1, thanks for posting!

Hmm that's interesting. Does attrs have an API that is interchangeable with the built-in dataclasses?

For parser.add_arguments(<attrs.dataclass>, dest="foo") to work, what we'd need are equivalents to:

• dataclasses.fields(dataclass_type_or_instance) -> Iterable[dataclasses.Field]
• dataclasses.is_dataclass(dataclass) -> bool
• dataclasses.Field attributes:
  • name: str
  • type: str | type
  • default: Any | dataclasses.MISSING
  • default_factory: Callable[[], Any] | dataclasses.MISSING
  • metadata: dict

If there's a way of get this information from the attrs.dataclass, then yeah, this would be feasible, nice contribution! :)

[lebrice]

Hey @bilelomrani1, do you know if attrs has this kind of interop with dataclasses ?

[bilelomrani1]

Hi @lebrice I'm sorry for the long delay. I no longer need this feature as I found an existing alternative for my use case. But I can still provide some answers if you are still interested in this feature, I once wrote a dataclasses/attrs parser some time ago, the code is available here.
Looking at it, here is what I used:

• attr.fields(attr_type): list of attrs fields, containing the field name, type, factory/default value.
• attr.has(attr_type) --> bool: equivalent of dataclasses.is_dataclass(dataclass) -> bool