feat(datatypes): support ibis.dtype(nullable=None) #11694
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NickCrews
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Oct 16, 2025
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| @classmethod | ||
| def from_string(cls, text: str, nullable: bool = True) -> DataType: | ||
| def from_string(cls, text: str, nullable: bool | None = None) -> DataType: |
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The subclasses SqlglotType and PostgresType already use this signature. So this is more of a bugfix to bring this ABC into compliance with how we actually are using them.
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NickCrews
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Oct 16, 2025
| nullable = True | ||
| if pa.types.is_null(typ): | ||
| return dt.null | ||
| return dt.null(nullable=nullable) |
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ah, I guess this is a tiny behavior change. Before, ibis.dtype(pa.null(), False) would still give dt.Null(nullable=True). Now it correctly gives dt.Null(nullable=False)
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This removes the footgun where currently
ibis.dtype("!int64", nullable=True)results in a non-nullable dtype. Besides that, this shouldn't affect users at all.This also removes the slightly smaller footgun where
ibis.dtype(existing_dtype)would always return a nullable version. I think it is preferable for this to be a no-op (return the original dtype unchanged), and only to adjust the nullability if it is explicitly provided.This also sets us up to work with any future type systems that have an inherent sense of nullability. All the ones we currently support (numpy, pandas, arrow, and polars) do not keep track of nullability, so this doesn't do much there. This might not be much of a reason to do this. IF you want, we could limit the changes just to the top-level dtype() function, and not adjust the TypeMapper.to_ibis() signature, but I thought I might as well make everything consistent, its a tiny bit more code but not much.
Finally, this adds a lot more examples to the docstring for dtype() so that users get a taste of the string DSL.
This was inspired by #11607, and would help reduce the scope of that PR.