Use of ParamSpec only works in Python 3.10+

[luong-komorebi]

This morning we faced this issue

for a working service that has received no code change in dependencies recently. By tracking the root cause, I was able to detect that it was caused by typing-extension, which was used by blinker, which was part of Flask (our direct dependency). A similar issue with the same footprint could be found here and here. Typing extension didnt include a change log for version < 4 so I cannot track down which version starts this issue.

We either need to do some if else check to ensure that when a combination of packages is used, blinker is able to use paramspec. Another intrusive way is to declare a minimum version for typing extension.

[davidism]

Another intrusive way is to declare a minimum version for typing extension.

Yes, this is the correct way. It sounds like you already had a version of typing_extensions installed, which was not upgraded when you installed Flask-SQLAlchemy. Since we depend on features from a later version, we should set that minimum version.

[pgjones]

I think I'll require ParamSpec > 4.2 (first mention of ParamSpec), and I'll release a 1.6.1 to fix this and the missing py.typed file.

[pgjones]

Fixed with 1.6.1, now released.