No deprecation warning, while calling a function of an imported module about polars HOT 3 CLOSED

Thanks for the report, but this is not an issue with Polars.

The Python docs are really clear about this. DeprecationWarnings are ignored outside the current main.

Also, FutureWarning is not applicable here. It is intended for end users, not for developers. Polars should not throw any FutureWarnings.

If you want to see DeprecationWarnings outside of the main module, you can explicitly opt in to that:

import warnings

warnings.filterwarnings("always", category=DeprecationWarning)

from polars.

I am not sure. Users of a library that is written in Polars shouldn't see that deprecation warning. That warning is intended for the developers of that library, not the users up the stack.

from polars.

Sure but like this direct users of Polars who have defined their own convenience functions (e.g. @stfdxv ) risk not seeing the warning

The other extreme is to do what pandas currently does which is to always raise FutureWarning, which is always shown. This is too noisy in my opinion, users see warnings which they can't do anything about.

A middle-ground option, which I'm hoping pandas will move to too (long discussion here pandas-dev/pandas#54970), is:

• start by raising DeprecationWarning. This will be seen my library developers and end users directly invoking deprecated functions
• after some time, change it to FutureWarning. This will be visible by everyone, including end users who have defined their own convenience functions (e.g. @stfdxv )
• finally, enforce the deprecation

Example following the Polars policy:

• Polars 0.20.11 deprecates pl.col('a').meta.write_json in favour of pl.col('a').meta.serialize, and emits a DeprecationWarning
• In Polars 1.1.0 (some time in the middle of the 1.x series? When there's a feeling that the next minor release will be the final non-breaking one? Up for discussion), the DeprecationWarning changes to FutureWarning
• In Polars 2.0.0, Expr.meta.write_json is removed

from polars.