3 ms·

If I was PyPy, I'd have dropped all 2.x effort and focused on Python 3.8 compatibility.

chc 8y ago
I might be mistaken, but it was my impression that the changes to the 2.7 version now are mostly "core" changes that also apply to PyPy3. Basically, most language-specific work is going toward Python 3, and PyPy2 benefits when features they have in common are improved.
wyldfire 8y ago
Actually, there's been quite some speculation that PyPy could inherit the 2.x crown when CPython expires its support for 2.x (1 Jan 2020). PyPy is probably the best non-CPython Python 2.7 implementation, so it's a natural fit to some degree. I suppose it's all dependent on where the PyPy team wants to spend its time and whether or not someone might fund them for this effort (Canonical, RH, etc). I don't know that they have the will to bug-for-bug reproduce CPython but the C API emulation layer added within the last few years probably means that it will be really high fidelity.
- nikolay 8y ago
  Well, this whole Python 2 & 3 is a huge fiasco. Supporting 2.x keeps the circus forever on.
  - wyldfire 8y ago
    I don't know that I agree that it's a fiasco. I've been asked to work on a PDP11 in the last few years and while it was mind-boggling (the request -- I turned it down), it was understandable from a business perspective. So I can see how some businesses might want Just A Little While Longer on Python 2.x. shrug, use python 3.x and don't sweat the fact that some folks are still stuck on 2.x. You certainly can't stop someone from offering support for 2.x -- the language is well defined and the reference implementation is open source. Anyone out there could put up a "Python 2.x Support: Cheap!" sign and be in business.
    - nikolay 8y ago
      It surely is. There's a reason behind why support for old versions ends at some point.
  - josefx 8y ago
    Reinventing the wheel keeps the circus going forever. As long as python 2 is supported I don't have to touch any of the scripts I have to "maintain". The moment I am forced to migrate everything to Python 4 (they broke everything already, why not again) I will have to deal with a huge amount of pointless busywork just trying to restore functionality.
    - nikolay 8y ago
      Yeah, this is how to world moves forward - otherwise, we'd all be still watching VHS movies. Plus, there's this lovely tool called 2to3.
      - josefx 8y ago
        Funnily I can still watch VHS movies on a relatively new TV. Just had to plug in the VHS recorder and play, meanwhile the description of 2to3 makes it look like a plug and pray. I mean really? A script that might mention some cases it can't fix as warnings. "optional" fixes that replace missing classes with incompatible replacements, giving you the "choice" of fixing the mess by hand. Also an apparently unstable API for your own fixes, doubling down on breaking your code while you try to fix your broken code has to be dedication. > Note The lib2to3 API should be considered unstable and may change drastically in the future.
        nikolay 8y ago
        Well, 2to3 works surprisingly well and I've converted tons of projects with it. Most major Python projects support both 2 and 3, so, private codebases, which "just work", should stay on the "just working" old versions of the interpreter instead of insisting maintainers to waste time entertaining their laziness, because things that "just work" don't require ANY updates, right?
        josefx 8y ago
        I am happy as long as I can plug-in old versions of the interpreter in a system 10 years from now as easily as I could plug-in my VHS recorder into the TV. Might be able to do that if I install a windows version of python on Wine, there is a good chance (~100%) that the dependencies of python on Linux will not remain compatible that long.
0xADEADBEE 8y ago
It'll be interesting to see if there's an upswing in PyPy usage over the next few months, for the explicit reason that they're not slated to drop 2.7 compatibility. I would imagine a noticeable percentage of 2.7 codebases without the available resources for a rewrite (that has by definition, no business value) would welcome anything close to a drop-in replacement. I'll be very interested to see if I'm wrong though!
fijal 8y ago
There are two things in play here - one is that pypy is a large py2-only codebase that is unlikely to be ported. Second is that maintaining python 2 both does not cost much and it's used by the majority of our users, despite of what you hear on the internet. So, there is both good reason to keep it and a large amount of work to drop it.

chc 8y ago

I might be mistaken, but it was my impression that the changes to the 2.7 version now are mostly "core" changes that also apply to PyPy3. Basically, most language-specific work is going toward Python 3, and PyPy2 benefits when features they have in common are improved.

wyldfire 8y ago

Actually, there's been quite some speculation that PyPy could inherit the 2.x crown when CPython expires its support for 2.x (1 Jan 2020). PyPy is probably the best non-CPython Python 2.7 implementation, so it's a natural fit to some degree. I suppose it's all dependent on where the PyPy team wants to spend its time and whether or not someone might fund them for this effort (Canonical, RH, etc). I don't know that they have the will to bug-for-bug reproduce CPython but the C API emulation layer added within the last few years probably means that it will be really high fidelity.

nikolay 8y ago
Well, this whole Python 2 & 3 is a huge fiasco. Supporting 2.x keeps the circus forever on.
- wyldfire 8y ago
  I don't know that I agree that it's a fiasco. I've been asked to work on a PDP11 in the last few years and while it was mind-boggling (the request -- I turned it down), it was understandable from a business perspective. So I can see how some businesses might want Just A Little While Longer on Python 2.x. shrug, use python 3.x and don't sweat the fact that some folks are still stuck on 2.x. You certainly can't stop someone from offering support for 2.x -- the language is well defined and the reference implementation is open source. Anyone out there could put up a "Python 2.x Support: Cheap!" sign and be in business.
  - nikolay 8y ago
    It surely is. There's a reason behind why support for old versions ends at some point.
- josefx 8y ago
  Reinventing the wheel keeps the circus going forever. As long as python 2 is supported I don't have to touch any of the scripts I have to "maintain". The moment I am forced to migrate everything to Python 4 (they broke everything already, why not again) I will have to deal with a huge amount of pointless busywork just trying to restore functionality.
  - nikolay 8y ago
    Yeah, this is how to world moves forward - otherwise, we'd all be still watching VHS movies. Plus, there's this lovely tool called 2to3.
    - josefx 8y ago
      Funnily I can still watch VHS movies on a relatively new TV. Just had to plug in the VHS recorder and play, meanwhile the description of 2to3 makes it look like a plug and pray. I mean really? A script that might mention some cases it can't fix as warnings. "optional" fixes that replace missing classes with incompatible replacements, giving you the "choice" of fixing the mess by hand. Also an apparently unstable API for your own fixes, doubling down on breaking your code while you try to fix your broken code has to be dedication. > Note The lib2to3 API should be considered unstable and may change drastically in the future.
      - nikolay 8y ago
        Well, 2to3 works surprisingly well and I've converted tons of projects with it. Most major Python projects support both 2 and 3, so, private codebases, which "just work", should stay on the "just working" old versions of the interpreter instead of insisting maintainers to waste time entertaining their laziness, because things that "just work" don't require ANY updates, right?
        josefx 8y ago
        I am happy as long as I can plug-in old versions of the interpreter in a system 10 years from now as easily as I could plug-in my VHS recorder into the TV. Might be able to do that if I install a windows version of python on Wine, there is a good chance (~100%) that the dependencies of python on Linux will not remain compatible that long.

0xADEADBEE 8y ago

It'll be interesting to see if there's an upswing in PyPy usage over the next few months, for the explicit reason that they're not slated to drop 2.7 compatibility. I would imagine a noticeable percentage of 2.7 codebases without the available resources for a rewrite (that has by definition, no business value) would welcome anything close to a drop-in replacement. I'll be very interested to see if I'm wrong though!

fijal 8y ago

There are two things in play here - one is that pypy is a large py2-only codebase that is unlikely to be ported. Second is that maintaining python 2 both does not cost much and it's used by the majority of our users, despite of what you hear on the internet. So, there is both good reason to keep it and a large amount of work to drop it.