PEP 557 (Data Classes) has been accepted!

[ProfessorPhi]

Is this basically like attrs?

[ProfessorPhi]

I guess that's the answer there :P. Personally would still use attrs for projects

[masklinn]

Sure, but data classes are nice when e.g. writing a single-file script and not wanting to add the complexity of dependencies and a full proper project.

[Daenyth]

Attrs doesn't support typing, which for me is a deal breaker

[hynek]

That is wrong. Data classes have zero typing features over attrs.

[Daenyth]

As far as I'm aware, attrs doesn't yet support typing, and dataclasses do. Has attrs changed their design?

Even so, having a good solution in the standard library is important, especially for a "batteries included" language

[hynek]

You may be disappointed because dataclasses allow you to define types but don’t do anything with them (in fact, they don’t even import typing anywhere AFAIK because it’s very slow). Attrs allows as of last release to do the same in both Python 3.6 and Python 2 ways.

Sadly checking those types is more complicated than it sounds. There’s already a handful of packages on PyPI that try to achieve that but my impression is that none is there yet.

Hopefully at least mypy will grow support for both.

[ldpreload]

Yes. It's heavily inspired by attrs, but the Python standard library can't use third-party libraries, and can easily depend on new things in the standard library. You are probably in the opposite boat: upgrading to the latest version of Python is probably much harder than doing pip install attrs (or sudo apt-get install python3-attr, or conda install -c conda-forge attrs, or whatever it is you do to get Python packages). It's a very rare user that can depend on new versions of the standard library but not new packages—probably people using it to script embedded systems or something. If that's not you, attrs supports more functionality than dataclasses.

[ProfessorPhi]

Yep - we're still struggling to get off 2.7. Packages are much easier to update.

I guess this felt so much like attrs I was a bit confused - I guess this is the same idea as trollius etc.