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16 years after the start of Python 3 and we're still discussing this. I hope other languages and platforms have paid attention to this transition. Sometimes on

16 years after the start of Python 3 and we're still discussing this. I hope other languages and platforms have paid attention to this transition. Sometimes one's only purpose in life is to serve as a warning to others...

reedwolf 7y ago
Not sure what you mean. This was the best way to do it. Slowly and painlessly. Any project that matters is now on 3. For a bad transition, look at Perl 6, a debacle so big it was renamed Raku and became a different programming language.
- TylerE 7y ago
  It was, by any standard, just about the worst way to do it. Fractured community Lost trust Endless bikeshedding All for very little objective gain.
  - mixmastamyk 7y ago
    Nope, perl was mentioned just above. This was the second worst way. ;-)
    - TylerE 7y ago
      The distinction I would make is that they never told anyone to migrate production code to Perl 6.
      - mixmastamyk 7y ago
        They couldn't even if they wanted because it didn't ship for twenty years.
        TylerE 7y ago
        But that’s why Python is much worse than Perl. The Python team was trying to move the world to 3 when it was demonstrably inferior
        mixmastamyk 7y ago
        If only we all could fail so spectacularly, growing an order of magnitude in the same time period. I wouldn’t use Python 2 now if you paid me.
        b2gills 7y ago
        Correction 15 years. I was using it to an extent in 2009. (I'm sure I was using it before that.) At which point it had only been 9 years in development. --- You can have it fast, good, or cheap. Pick at most 2. Since Perl 6 was entirely volunteer driven it was always going to be cheap. So the only real choice was between fast and good. I'm glad the choice was to make it good rather than fast. We could have gone the Python route where they chose fast. Only they didn't really even manage to do that much better than Perl6. --- And what did Python get, a language that is only slightly better in a handful of ways. (Every one that I've heard of is reminiscent of one that Perl5 has dealt with over the years without breaking backwards compatibility.) Perl6 meanwhile is a large step that questions long held beliefs of what a programming language can even be. It calls into question what parsers can be, what regexes can be. It calls into question why language divides exist. Why can't a language be at both ends of the spectrum at the same time. Even if Raku doesn't take off, it will likely be a source of inspiration for future language designers. (It already has to a small degree.) Whereas Python3 is just a slightly nicer Python. One that not everyone has transitioned to yet. Some may never. (Some have even transitioned to Go instead, since it has very similar semantics.) --- There were also some health issues during the Perl6 project which held back the progress to a significant degree. We don't know how many years that added to the total.
  - warlog 7y ago
    The language is pretty sweet. I guess nothing that you can't do other languages, but it has some good mojo now it's raku.
- bartread 7y ago
  > This was the best way to do it. Was it really though? Speaking as somebody who considered learning Python several times over the course of a decade I was seriously put off by the protracted uncertainty around 2 vs 3. There was a long period - years long - where everything that "mattered" seemed to be supported by and available for Python 2 and there was a ton of FUD, along with genuine issues, about incompatibilities with Python 3. When I asked which version I should learn I felt like I couldn't get a straight answer. I never had a strong need to learn Python: I just thought it might be a fun and useful thing to do, because people seemed to like the language. But I wasn't interested in investing time in something that might wind up unsupported in a few years, and because I didn't have any serious need for it, it wasn't worth digging through the morass of misinformation to get to the truth. As an outsider it was extremely unclear to me which version of Python would be actively supported for the long term. 20:20 hindsight says 3 was the future but - and maybe this is just bad mar-comms - back then it seemed like there was a reasonable chance it was either going to be a dead end or exist perpetually in this weird no-mans-land of "not quite ready for prime time". Had I learned it there's a good chance I probably would have used it for something more serious by now. But I didn't, and so I have to disagree: it was done extremely poorly.
  - rubber_duck 7y ago
    > Speaking as somebody who considered learning Python several times over the course of a decade I was seriously put off by the uncertainty around 2 vs 3. And yet Python is still one of the most popular programming languages, with its popularity and use growing. Theoretically it could have been done better, but it was going to take time no matter what approach you took and it worked out in the end.
  - barbecue_sauce 7y ago
    I don't really understand why there has been so much hemming and hawing about Python 2 vs Python 3 with regard to the language itself. If you already know a few programming languages (rather than being a neophyte coder), Python 2 and Python 3 are so similar that their major differences can be summed up in one or two pages of code examples. Sure, they're not backwards compatible, but if you know one, you'll have no trouble being able to at least read and understand the other without much effort. The bigger issue is the ecosystem taking the time to catch up. Also, I'm not sure that Python 3 is really much of an improvement over 2 rather than just different.
- ridiculous_fish 7y ago
  v8 matters and still requires Python2 to build. https://bugs.chromium.org/p/chromium/issues/detail?id=942720 https://bugs.chromium.org/p/chromium/issues/detail?id=942720
- 0xff00ffee 7y ago
  Bringing up Perl 6? That was a low blow. ;-) I'll be dead in my grave before I recognize anything past 5.8.1. Just like how they still haven't made The Matrix 3. Sh. Quiet, you. :)
- antoncohen 7y ago
  Python tried to pull a Perl 6 and failed. Python 3 was done as a flag day, a big breaking change you need to switch over to. Originally Python 3 and Python 2 lacked features that would make it possible to write code that is compatible with both versions (like `u"foo"` syntax). Slowly they added things to Python 2 and 3 to make it easier to slowly transition. But it was still full of unnecessary breaking changes. - The `print()` function is nice, but they could have left in the `print` statement for a transitional (deprecation) period. Or left the `print` statement in, and advise against its use. - A lot of the incompatibilities are just stdlib modules being moved around unnecessarily. They could have made both import paths work for a transitional (deprecation) period. Or let the old paths continue to work forever, and just document usage of the new paths. - All the new features in Python 3 (async, nice helper functions, etc.) are compatible with Python 2. They could have added them to Python 2. The only true breaking change was unicode literal strings. But again, that could be handled with a slow transitional (deprecation) period. The Python 2 stdlib could have been made compatible with both types of strings (as nearly all third-party libraries have). And users could have been told to `from __future__ import unicode_literals` for a transitional (deprecation) period, to ensure their code is compatible before it becomes the default. Basically Python 3 could have been a single hard breaking change (unicode literal strings), with a smooth transition. Instead they decided to make Python 2 and 3 diverge from each other, making it harder to do the transition.
  - mcv 7y ago
    I think next time, when you need to do breaking changes, give it a new name, so the new thing gets to be hot and new, rather than a problem. Or do what javascript did: stay compatible with the stupid old way, but build a brand new language on top of it.
    - b2gills 7y ago
      That's exactly what Perl has been doing since 1987. Where do you think the idea for `"use strict"` in JavaScript came from? use v5.8; use strict; use warnings;
  - joshuamorton 7y ago
- sedatk 7y ago
  A backwards compatible and incremental move would have been much better. Microsoft has been doing that on C#, can't be happier.
- pseudalopex 7y ago
  The plan was for people to write Python 2 and generate Python 3.[1] What eventually worked was making it possible to have a single code base. Imagine if that had been possible all along. [1] http://python-notes.curiousefficiency.org/en/latest/python3/questions_and_answers.html#what-other-changes-have-occurred-that-simplify-migration http://python-notes.curiousefficiency.org/en/latest/python3/...
- ethelward 7y ago
  > For a bad transition, look at Perl 6 At first glance, you're right. But if you take a closer look, from a purely pragmatic perspective, there are now at least two coexisting ecosystems in two different languages, peacefully sailing along. Python 2/3 is in this kind of weird twilight zones that the two versions are far away enough that you can't have a smooth transition like in e.g. C++, Java, Rust, Go, etc., but still close enough that there is not a clear cut like in Perl5/Raku. So for a few years, one had to juggle with some of the libs that were 2-and-3 compatible, some that were 2-only, and the others that were 3-only. C++ et al. let your code evolve Theseus ship-like; Perl makes you build a new ship; and Python tells you that your ship should be OK if you repaint that thing, change a bit of that one, oh, and by the way, you'll have to check very carefully your bunkers, because the boilers will explode if every coal nut is not Unicode-compatible.
Tade0 7y ago
I remember when in late 2009 I wanted to pick up Python and was conflicted whether I should learn Python 3 or 2 - obviously I wanted to try the new and shiny, but was put off by the lack of compatible libraries at the time. Eventually settled for none. I didn't know that at the time, but later it proved to be a career defining moment.
- mtalantikite 7y ago
  Similar thing happened with me starting around the same time (Python 3k I think they were calling it in 2007/2008). Every few years I’d look to Python again and the same split was happening in the ecosystem. It always put me off. Definitely changed the course of my programming career.
  - dave_sullivan 7y ago
    What did you end up learning instead? Learning python (2, then 3) changed the course of my career for the better, starting with web development, then machine learning. I’m doing mostly javascript these days but still use python a lot for web scraping, business process automation, and machine learning. It’s pretty versatile.
    - mtalantikite 7y ago
      I spent a lot of time with Ruby as a younger developer along with JavaScript, but these days spend most of my time in Go. Some Swift and Rust depending on what I’m working on.
downerending 7y ago
The problem is that it wasn't really a transition. Rather, Python3 is a new language that is deceptively similar to--and crucially, not compatible with--Python2. Nothing really wrong with that, but it should have been called "Cobra" or something. And the weird jihad for killing off Python2 should never have happened. If everyone moved to Cobra on their own, great. But there should have been no beatings.
- oliwarner 7y ago
  This assumes that you can splinter developers, the community and all their efforts into two new things and still have the same operational power. The act of killing off V2 gives downstream developers the right to stop supporting it; regain some focus.
  - downerending 7y ago
    > The act of killing off V2 gives downstream developers the right to stop supporting it Seems like a strange way to give developers more "rights".
    - oliwarner 7y ago
      Call it what you will but if python 1 and 2 were still supported, I'd have customers demanding I support them indefinitely. This way there's no expectation, I get to wash my hands of it all. And without an awkward "I'm moving to Viper now chaps". It's a system update paradigm that people understand.
      - downerending 7y ago
        I'm old school--I try to give my customers what they want.
        oliwarner 7y ago
        That works when you have one or two customers per codebase. It's still not great. Context switching Python 2 and 3 is getting increasingly hard as 3 diverges. But when you have a few dozen customers on a single product, supporting edge-cases that require core forks becomes incredibly hard. Especially when you need modern Python features. We tried it. It doubled TTL for simple patches, and meant the Py2 version fell behind in terms of gross features. It was expensive for us, worse for the customer, so we dropped it and moved to a unified core. We had one customer threaten to leave but they didn't. Somebody in their IT department rubbed two brain cells together and agreed with our assessment. A customer might leave over this sort of behaviour, but again this worked out to be more cost effective, so we would probably do the same when Python 3 is EOL. Wheel keeps turning.

reedwolf 7y ago

Not sure what you mean. This was the best way to do it. Slowly and painlessly. Any project that matters is now on 3. For a bad transition, look at Perl 6, a debacle so big it was renamed Raku and became a different programming language.

TylerE 7y ago
It was, by any standard, just about the worst way to do it. Fractured community Lost trust Endless bikeshedding All for very little objective gain.
- mixmastamyk 7y ago
  Nope, perl was mentioned just above. This was the second worst way. ;-)
  - TylerE 7y ago
    The distinction I would make is that they never told anyone to migrate production code to Perl 6.
    - mixmastamyk 7y ago
      They couldn't even if they wanted because it didn't ship for twenty years.
      - TylerE 7y ago
        But that’s why Python is much worse than Perl. The Python team was trying to move the world to 3 when it was demonstrably inferior
        mixmastamyk 7y ago
        If only we all could fail so spectacularly, growing an order of magnitude in the same time period. I wouldn’t use Python 2 now if you paid me.
      - b2gills 7y ago
        Correction 15 years. I was using it to an extent in 2009. (I'm sure I was using it before that.) At which point it had only been 9 years in development. --- You can have it fast, good, or cheap. Pick at most 2. Since Perl 6 was entirely volunteer driven it was always going to be cheap. So the only real choice was between fast and good. I'm glad the choice was to make it good rather than fast. We could have gone the Python route where they chose fast. Only they didn't really even manage to do that much better than Perl6. --- And what did Python get, a language that is only slightly better in a handful of ways. (Every one that I've heard of is reminiscent of one that Perl5 has dealt with over the years without breaking backwards compatibility.) Perl6 meanwhile is a large step that questions long held beliefs of what a programming language can even be. It calls into question what parsers can be, what regexes can be. It calls into question why language divides exist. Why can't a language be at both ends of the spectrum at the same time. Even if Raku doesn't take off, it will likely be a source of inspiration for future language designers. (It already has to a small degree.) Whereas Python3 is just a slightly nicer Python. One that not everyone has transitioned to yet. Some may never. (Some have even transitioned to Go instead, since it has very similar semantics.) --- There were also some health issues during the Perl6 project which held back the progress to a significant degree. We don't know how many years that added to the total.
- warlog 7y ago
  The language is pretty sweet. I guess nothing that you can't do other languages, but it has some good mojo now it's raku.
bartread 7y ago
> This was the best way to do it. Was it really though? Speaking as somebody who considered learning Python several times over the course of a decade I was seriously put off by the protracted uncertainty around 2 vs 3. There was a long period - years long - where everything that "mattered" seemed to be supported by and available for Python 2 and there was a ton of FUD, along with genuine issues, about incompatibilities with Python 3. When I asked which version I should learn I felt like I couldn't get a straight answer. I never had a strong need to learn Python: I just thought it might be a fun and useful thing to do, because people seemed to like the language. But I wasn't interested in investing time in something that might wind up unsupported in a few years, and because I didn't have any serious need for it, it wasn't worth digging through the morass of misinformation to get to the truth. As an outsider it was extremely unclear to me which version of Python would be actively supported for the long term. 20:20 hindsight says 3 was the future but - and maybe this is just bad mar-comms - back then it seemed like there was a reasonable chance it was either going to be a dead end or exist perpetually in this weird no-mans-land of "not quite ready for prime time". Had I learned it there's a good chance I probably would have used it for something more serious by now. But I didn't, and so I have to disagree: it was done extremely poorly.
- rubber_duck 7y ago
  > Speaking as somebody who considered learning Python several times over the course of a decade I was seriously put off by the uncertainty around 2 vs 3. And yet Python is still one of the most popular programming languages, with its popularity and use growing. Theoretically it could have been done better, but it was going to take time no matter what approach you took and it worked out in the end.
- barbecue_sauce 7y ago
  I don't really understand why there has been so much hemming and hawing about Python 2 vs Python 3 with regard to the language itself. If you already know a few programming languages (rather than being a neophyte coder), Python 2 and Python 3 are so similar that their major differences can be summed up in one or two pages of code examples. Sure, they're not backwards compatible, but if you know one, you'll have no trouble being able to at least read and understand the other without much effort. The bigger issue is the ecosystem taking the time to catch up. Also, I'm not sure that Python 3 is really much of an improvement over 2 rather than just different.
ridiculous_fish 7y ago
v8 matters and still requires Python2 to build. https://bugs.chromium.org/p/chromium/issues/detail?id=942720 https://bugs.chromium.org/p/chromium/issues/detail?id=942720
0xff00ffee 7y ago
Bringing up Perl 6? That was a low blow. ;-) I'll be dead in my grave before I recognize anything past 5.8.1. Just like how they still haven't made The Matrix 3. Sh. Quiet, you. :)
antoncohen 7y ago
Python tried to pull a Perl 6 and failed. Python 3 was done as a flag day, a big breaking change you need to switch over to. Originally Python 3 and Python 2 lacked features that would make it possible to write code that is compatible with both versions (like `u"foo"` syntax). Slowly they added things to Python 2 and 3 to make it easier to slowly transition. But it was still full of unnecessary breaking changes. - The `print()` function is nice, but they could have left in the `print` statement for a transitional (deprecation) period. Or left the `print` statement in, and advise against its use. - A lot of the incompatibilities are just stdlib modules being moved around unnecessarily. They could have made both import paths work for a transitional (deprecation) period. Or let the old paths continue to work forever, and just document usage of the new paths. - All the new features in Python 3 (async, nice helper functions, etc.) are compatible with Python 2. They could have added them to Python 2. The only true breaking change was unicode literal strings. But again, that could be handled with a slow transitional (deprecation) period. The Python 2 stdlib could have been made compatible with both types of strings (as nearly all third-party libraries have). And users could have been told to `from __future__ import unicode_literals` for a transitional (deprecation) period, to ensure their code is compatible before it becomes the default. Basically Python 3 could have been a single hard breaking change (unicode literal strings), with a smooth transition. Instead they decided to make Python 2 and 3 diverge from each other, making it harder to do the transition.
- mcv 7y ago
  I think next time, when you need to do breaking changes, give it a new name, so the new thing gets to be hot and new, rather than a problem. Or do what javascript did: stay compatible with the stupid old way, but build a brand new language on top of it.
  - b2gills 7y ago
    That's exactly what Perl has been doing since 1987. Where do you think the idea for `"use strict"` in JavaScript came from? use v5.8; use strict; use warnings;
- joshuamorton 7y ago
sedatk 7y ago
A backwards compatible and incremental move would have been much better. Microsoft has been doing that on C#, can't be happier.
pseudalopex 7y ago
The plan was for people to write Python 2 and generate Python 3.[1] What eventually worked was making it possible to have a single code base. Imagine if that had been possible all along. [1] http://python-notes.curiousefficiency.org/en/latest/python3/questions_and_answers.html#what-other-changes-have-occurred-that-simplify-migration http://python-notes.curiousefficiency.org/en/latest/python3/...
ethelward 7y ago
> For a bad transition, look at Perl 6 At first glance, you're right. But if you take a closer look, from a purely pragmatic perspective, there are now at least two coexisting ecosystems in two different languages, peacefully sailing along. Python 2/3 is in this kind of weird twilight zones that the two versions are far away enough that you can't have a smooth transition like in e.g. C++, Java, Rust, Go, etc., but still close enough that there is not a clear cut like in Perl5/Raku. So for a few years, one had to juggle with some of the libs that were 2-and-3 compatible, some that were 2-only, and the others that were 3-only. C++ et al. let your code evolve Theseus ship-like; Perl makes you build a new ship; and Python tells you that your ship should be OK if you repaint that thing, change a bit of that one, oh, and by the way, you'll have to check very carefully your bunkers, because the boilers will explode if every coal nut is not Unicode-compatible.

Tade0 7y ago

I remember when in late 2009 I wanted to pick up Python and was conflicted whether I should learn Python 3 or 2 - obviously I wanted to try the new and shiny, but was put off by the lack of compatible libraries at the time. Eventually settled for none. I didn't know that at the time, but later it proved to be a career defining moment.

mtalantikite 7y ago
Similar thing happened with me starting around the same time (Python 3k I think they were calling it in 2007/2008). Every few years I’d look to Python again and the same split was happening in the ecosystem. It always put me off. Definitely changed the course of my programming career.
- dave_sullivan 7y ago
  What did you end up learning instead? Learning python (2, then 3) changed the course of my career for the better, starting with web development, then machine learning. I’m doing mostly javascript these days but still use python a lot for web scraping, business process automation, and machine learning. It’s pretty versatile.
  - mtalantikite 7y ago
    I spent a lot of time with Ruby as a younger developer along with JavaScript, but these days spend most of my time in Go. Some Swift and Rust depending on what I’m working on.

downerending 7y ago

The problem is that it wasn't really a transition. Rather, Python3 is a new language that is deceptively similar to--and crucially, not compatible with--Python2. Nothing really wrong with that, but it should have been called "Cobra" or something. And the weird jihad for killing off Python2 should never have happened. If everyone moved to Cobra on their own, great. But there should have been no beatings.

oliwarner 7y ago
This assumes that you can splinter developers, the community and all their efforts into two new things and still have the same operational power. The act of killing off V2 gives downstream developers the right to stop supporting it; regain some focus.
- downerending 7y ago
  > The act of killing off V2 gives downstream developers the right to stop supporting it Seems like a strange way to give developers more "rights".
  - oliwarner 7y ago
    Call it what you will but if python 1 and 2 were still supported, I'd have customers demanding I support them indefinitely. This way there's no expectation, I get to wash my hands of it all. And without an awkward "I'm moving to Viper now chaps". It's a system update paradigm that people understand.
    - downerending 7y ago
      I'm old school--I try to give my customers what they want.
      - oliwarner 7y ago
        That works when you have one or two customers per codebase. It's still not great. Context switching Python 2 and 3 is getting increasingly hard as 3 diverges. But when you have a few dozen customers on a single product, supporting edge-cases that require core forks becomes incredibly hard. Especially when you need modern Python features. We tried it. It doubled TTL for simple patches, and meant the Py2 version fell behind in terms of gross features. It was expensive for us, worse for the customer, so we dropped it and moved to a unified core. We had one customer threaten to leave but they didn't. Somebody in their IT department rubbed two brain cells together and agreed with our assessment. A customer might leave over this sort of behaviour, but again this worked out to be more cost effective, so we would probably do the same when Python 3 is EOL. Wheel keeps turning.