asyncssh/connection.py need 'Self' in 'typing_extensions', but included in python standard library typing.py

[waketzheng]

Description

asyncssh/connection.py need 'Self' in 'typing_extensions', but included in python standard library typing.py

[ronf]

Is there a particular reason for the conditional here? In my experience, it should work just fine to continue to import Self from typing_extensions even after it is available in the Python standard library. Once I stop supporting older Python versions, I can switch the import to use "typing", but in the meantime I'd prefer not to clutter the code with conditionals if it can be avoided.

[waketzheng]

@ronf, I've updated it to only depend on typing-extensions when Python < 3.11.

[ronf]

You still haven't explained what you're trying to accomplish here. Yesterday, I checked in a change which moves all imports from typing_extensions to typing (specifically for Literal and Protocol), as those came into typing in Python 3.8. This leaves only Self for now as needing to come from typing_extensions, but there may be other types in the future that will need it as well. I think it's reasonable to require that typing_extensions be considered a required dependency, which it is right now.

On Python 3.11 and later, my understanding is that there should be no difference between importing Self from typing_extensions instead of typing. According to the typing_extensions documentation, there are even special provisions in static type checkers about this:

typing_extensions is treated specially by static type checkers such as mypy and pyright. Objects defined in typing_extensions are treated the same way as equivalent forms in typing.

So, I'd prefer not to put in unnecessary conditional imports for this.

[waketzheng]

Thanks for the clarification. My goal was to avoid installing typing_extensions on newer Python versions where the required typing features are already in the standard library.

Given your point that typing_extensions is considered a required dependency here and may be useful for future typing features, I agree this isn’t worth the extra conditional imports. I’ll close the PR. Thanks for explaining.

[ronf]

Thanks for your interest in AsyncSSH - let me know if you have any other issues or questions!