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ericvsmith / dataclasses

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Backport slots=True and kw_only=True from Python 3.10 #166

Closed ericvsmith closed 3 years ago

ericvsmith commented 3 years ago

I'm personally stuck on python 3.6 at a client's site, so I think I'll backport these. On the other hand, when that client moves to 3.7 it will break my code, so maybe it's not the best idea in the world. This issue is just to remind me about it.

Minitour commented 3 years ago

Any chance for an upcoming release for the kw_only backport? I find this a really useful feature for dataclasses.

ericvsmith commented 3 years ago

@Minitour : But then you couldn't write code that worked in 3.6 and 3.7. Is that really desirable? I'm not sure I want take on a backport under a different name that could be used in 3.6, 3.7, ..., 3.10. It seems unending. Maybe it's best to just say that this backport is 3.7 compatible and leave it at that.

Minitour commented 3 years ago

I am currently working on a project heavily written in 3.6 and we find the use of kw_only highly beneficial. This will allow us to inherit from classes that have default properties and not explicitly declare defaults for the fields of the sub-classes.

We have encountered many solutions out there to try and deal with the issue, but kw_only seems the most suitable one.

ericvsmith commented 3 years ago

What would you do if you upgraded to 3.7, where dataclasses doesn't have this feature?

ericvsmith commented 3 years ago

The problem is that "import dataclasses" in 3.7 will use the stdlib version of dataclasses, which does not have kw_only.

This could be solved by changing this repo's code to be "dataclasses2", or something. But I don't really want to try and support a bunch of old python versions.

But I feel your pain: I'm also working on a large 3.6 code base.

Minitour commented 3 years ago

I now understand the dilemma. Yes you are right at this point it will become a backport from the latest python version (3.10) to 3.6. Which will put 3.6 projects at an "advantage" where 3.7 projects will need a backport of its own.

In my opinion, this library is made specifically for 3.6 and you should not concern yourself with what happens with 3.7+, but to simply align with the latest specs of dataclasses. But that is my personal biased opinion.

ericvsmith commented 3 years ago

In my opinion, this library is made specifically for 3.6 and you should not concern yourself with what happens with 3.7+, but to simply align with the latest specs of dataclasses. But that is my personal biased opinion.

I don't think it's fair that the backport would set them up into a situation where the users cannot update to 3.7.

ericvsmith commented 3 years ago

I'm going to reject this.