Hi, I'm the original creator of https://github.com/typeddjango/django-stubs.
I guess it's my duty to start writing a DEP, so here is some preliminary
thoughts/questions to gather early feedback:
Main discussion points:
1. There's two ways to make Django compatible with type hinting and PEP484:
- Separate repo with `.pyi` files and mypy plugin (how it's done
currently with django-stubs).
Pros:
- no backwards-incompatible changes. Only required change from
Django is adding the `__class_getitem__` method to `QuerySet`
https://docs.python.org/3/reference/datamodel.html#object.__class_getitem__
to support generic parameters in 3.7+
- could be released separately
- no type hints code clutter
Cons:
- (as of now) there's no way to use type hints to typecheck Django
codebase itself. I think the official answer to that is to use retype tool
https://github.com/ambv/retype
(https://github.com/python/mypy/issues/5028#issuecomment-495942769), but so
far I didn't have any positive experience with that
- Inline type hints in the codebase.
Pros/Cons are exact reverse.
2. Whether to use Django own machinery to extract info for the
models/fields, or not.
Current implementation of django-stubs utilises `Apps` registry of Django
itself to extract some data for models/fields.
So, basically it executes codes first, then performs static analysis of
it.
Pros:
- lots of models/fields introspection could be extracted from the
`_meta` API => lower maintenance burden, more accurate types. In the
pre-1.0.0 versions of the django-stubs it was all done statically, and it
was very painful to implement.
Cons:
- mypy daemon mode (dmypy) is broken. It could be fixed, but it
requires some changes to mypy itself, and as `django.setup()` could not run
incrementally, it's not clear whether dmypy would provide any real benefits
over plain incremental mode.
- there could be some side effects in `django.setup()` invocation
- cannot typecheck invalid code
- slower to execute
Carlton, is it possible to move discussion to Github somehow?
On Wednesday, December 12, 2018 at 7:06:16 PM UTC+3, Carlton Gibson wrote:
>
> Hi all.
>
>
> Where are we with this Type Hinting work?
>
>
> I just closed https://code.djangoproject.com/ticket/30019 as needsinfo
> pointing back to this thread.
>
>
> As far as I can see:
>
> * There's keenness for this.
> * There's a number of people who are prepared to put in the effort.
> * But we just need a strategy.
>
> It looks then like a coordination problem. Do we just need to get said
> people in a (virtual) room...?
>
> Maybe one of you — anyone — opening a DEP to begin the conversation would
> be enough..
> (That's just an idea.)
>
> Looking here:
> https://github.com/django/deps/blob/master/final/0001-dep-process.rst#dep-submission-workflow
> I'd guess "Forming the Team" is relevant.
>
> Happy to help if I can.
> (I recall Frank mentioned it no too long ago...)
>
> Kind Regards,
>
> Carlton
>
>
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