Comment by wging
19 hours ago
I think the article is being careful not to say uv ignores _all_ upper bound checks, but specifically 4.0 upper bound checks. If a package says it requires python < 3.0, that's still super relevant, and I'd hope for uv to still notice and prevent you from trying to import code that won't work on python 3. Not sure what it actually does.
uv doesn't support <3.0 (I think the minimum is 3.8?) so it would be difficult for that to be relevant. But for pip, obviously yes.
I read the article as saying it ignores all upper-bounds, and 4.0 is just an example. I could be wrong though - it seems ambiguous to me.
But if we accept that it currently ignores any upper-bounds checks greater than v3, that's interesting. Does that imply that once Python 4 is available, uv will slow down due to needing to actually run those checks?
That would deliver a blow to the integrity of the rest of that section because those sorts of upper bound constraints immediately reducible to “true” cannot cause backtracking of any kind.
Are there any plans to actually make a 4.0 ever? I remember hearing a few years ago that after the transition to 3.0, the core devs kind of didn't want to repeat that mess ever again.
That said, even if it does happen, I highly doubt that is the main part of the speed up compared to pip.
I think there's a future where we get a 4.0, but it's not any time soon. I think they'd want an incredibly compelling backwards-incompatible feature before ripping that band-aid off. It would be setting up for a decade of transition, which shouldn't be taken lightly.
There are indeed not any such plans.