Declare missing dependencies

[squahtx]

It's best to look at the commits separately.
The first commit sorts the list of dependencies.

Fixes #289

[squahtx]

The minimum package versions for attrs and typing-extensions are copied from Synapse:
https://github.com/matrix-org/synapse/blob/eb39da6782b57c939450839097f32a14cba3ebfc/synapse/python_dependencies.py#L81-L85

The minimum package version for pyopenssl is copied from aioapns:
https://github.com/Fatal1ty/aioapns/blob/master/setup.py#L30

[DMRobertson]

Thanks for this!

[DMRobertson]

I'd put mypy-zope after mypy. But perhaps mypy- comes before mypy=?

Fine as it is, just an aside.

[squahtx]

Good spot, I'll fix it.

[DMRobertson]

Do we want/have a lower bound here?

[callahad]

Similarly to comment on typing-extensions, should we declare this as importlib_metadata; python_version < "3.8" (assuming we don't need the new importlib.metadata bits from 3.10)

[squahtx]

Perhaps. I have no idea what the lower bound should be

[squahtx]

For reference, this is what we do in python-signedjson: matrix-org/python-signedjson#9

[DMRobertson]

Another thought: why did CI miss this? I guess there's no equivalent of the olddeps job that Synapse has?

[callahad]

Another thought: why did CI miss this? I guess there's no equivalent of the olddeps job that Synapse has?

I think we're not testing against older python versions (e.g., I think setting up a matrix of ['3.7', '3.x'] would've found it)

[callahad]

Should we make this conditional so it's only installed on Py < 3.8? (And do the same for the import that needs it)

[DMRobertson]

I think we typically import directly from typing_extensions; would have to change the source to do a try...except ImportError... dance

[squahtx]

On the import side, mypy does not appreciate the obvious attempt:
https://mypy-play.net/?mypy=latest&python=3.10&gist=9ac99f23480e5c8bc86c68f94ce65b6c

if TYPE_CHECKING or sys.version_info < (3, 8, 0):
    from typing_extensions import Literal
else:
    from typing import Literal

works with mypy but always requires typing_extensions in dev.

[squahtx]

There's a PR to do the same for python-signedjson here: matrix-org/python-signedjson#12

[reivilibre]

Another thought: why did CI miss this? I guess there's no equivalent of the olddeps job that Synapse has?

Possibly because it was brought in by a dev dependency (e.g. mypy) and was present during the tests. :/

[reivilibre]

Another thought: why did CI miss this? I guess there's no equivalent of the olddeps job that Synapse has?

I think we're not testing against older python versions (e.g., I think setting up a matrix of ['3.7', '3.x'] would've found it)

3.7, the one we test with, is the oldest version we support iirc.

[DMRobertson]

I'm happy if CI is happy. Sanity check: would this have fixed the earlier deployment to matrix.org?

[squahtx]

I'm happy if CI is happy. Sanity check: would this have fixed the earlier deployment to matrix.org?

It ought to, assuming we do a pip install as part of the deployment.
I have no idea how we'd test this apart from doing another deployment.

[DMRobertson]

I have no idea how we'd test this apart from doing another deployment.

Maybe a pip install -e .? But yeah, probably best to try it and see.

[squahtx]

Maybe a pip install -e .? But yeah, probably best to try it and see.

A pip install -r <(./scripts-dev/old_deps.py) seems to be okay.

---

On another note, mypy really does not like conditional imports. Getting the right combination of type: ignores is far from simple.

Python 3.7:

sygnal/__init__.py:17: error: Module 'importlib.metadata' has no attribute 'PackageNotFoundError'  [attr-defined]
sygnal/__init__.py:17: error: Module 'importlib.metadata' has no attribute 'version'  [attr-defined]

Python 3.8, importlib_metadata installed:

sygnal/__init__.py:22: error: Incompatible import of "PackageNotFoundError" (imported name has type "Type[importlib_metadata.PackageNotFoundError]", local name has type "Type[importlib.metadata.PackageNotFoundError]")  [misc]

Python 3.8, importlib_metadata not installed:

sygnal/__init__.py:22: error: Name 'PackageNotFoundError' already defined (possibly by an import)  [no-redef]
sygnal/__init__.py:22: error: Name 'version' already defined (possibly by an import)  [no-redef]

[DMRobertson]

On another note, mypy really does not like conditional imports. Getting the right combination of type: ignores is far from simple.

Ouch, thanks for working through that. Is there any way that we could use TYPE_CHECKING to help? I guess not, since it's sensitive to the version of the stdlib that's running mypy(?)

[squahtx]

Ouch, thanks for working through that. Is there any way that we could use TYPE_CHECKING to help? I guess not, since it's sensitive to the version of the stdlib that's running mypy(?)

I can't see how, unless we unconditionally use importlib_metadata when type checking.

and you've made me realise that the dependencies are wrong. typing_extensions is only installed on Python <3.8, but we use it in type checking mode regardless.

[squahtx]

mypy brings in typing-extensions for us, but we should be explicit.

[DMRobertson]

I'm happy if CI is happy. Sanity check: would this have fixed the earlier deployment to matrix.org?

It ought to, assuming we do a pip install as part of the deployment. I have no idea how we'd test this apart from doing another deployment.

Ahhh, I was more getting at "why did the deployment fail?" so we could check this fixes it. The cause was an inability to import typing_extensions, but that's now been made a hard requirement.

Edit: a hard requirement on sufficiently old Pythons.

So I think this is hopefully good to go! 👍