[REQ] Allow overriding `__init__` of struct.dataclass

Python data classes allow the ovverriding of frozen data classes __init__ methods, that essentially just set all the relevant fields correctly.

I would like to ask that you expose that kwargument in your data class wrapper.

This is useful if a frozen data class is usually constructed starting from object_A but does not store object_A itself, but rather something computed starting from it. We can get around this by using a constructor method, but for a series of reasons the easiest things for us to do in NetKet would be to just override the __init__.

I don’t see reasons not to allow this, as it is allowed by the standard dataclass specification.

[jheek]

You can always define a vanilla dataclass with a custom flatten/unflatten. But in this case it’s your own responsibility to reconstruct without a trivial constructor(*fields) call.

Disclaimer I’m a big Rust fanboy: But I think “smart” constructors are not a good pattern. IMO a constructor should always be simple and what you want instead is a classmethod that creates your dataclass from some other value. A simple argument for this is that once the constructor starts being smart you could imagine wanting multiple constructors. But to maintain sanity these constructors should probably have a self-explanatory name. So I think what you should do is something like: FMJacobian.from_model(model, params, data)

The one exception to this could be simple type transformations that operate like a fixpoint. So for example transforming int -> (int,) such that when I pass in the (int,) again it stays (int,).

[marcvanzee]

@jheek Would it make sense to move this to a GH Discussion?