> And let's say numpy didn't expose a version number in a standard (which could be agreed upon in a PEP) field, then it would just throw an import exception. It wouldn't break any old code. And only packages with that explicit field would support the pinned version import.
Yes, this part actually is as simple as you imagine. But that means in practical terms that you can't use the feature until at best the next release of Numpy. If you want to say for example that you need at least version 2 (breaking changes, after all), well, there are already 18 published packages that meet that requirement but are unable to communicate that in the new syntax. This can to my understanding be fixed with post releases, but it's a serious burden for maintainers and most projects are just not going to do that sort of thing (it bloats PyPI, too).
And more importantly, that's only one of many problems that need to be solved. And by far the simplest of them.
Yes, this part actually is as simple as you imagine. But that means in practical terms that you can't use the feature until at best the next release of Numpy. If you want to say for example that you need at least version 2 (breaking changes, after all), well, there are already 18 published packages that meet that requirement but are unable to communicate that in the new syntax. This can to my understanding be fixed with post releases, but it's a serious burden for maintainers and most projects are just not going to do that sort of thing (it bloats PyPI, too).
And more importantly, that's only one of many problems that need to be solved. And by far the simplest of them.