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Comment by smoyer | Hacker News Reader

I like Python, but keeping both 2 and 3 alive for so long has caused problems that make it hard to justify for serious projects. What will your boss decide when half his developers say that the two branch is right for a task and half say the three branch should be used? He'll pick another language.

I'm not sure I'm willing to trust Ubuntu to decide this for me ... they also thought Unity was in my best interest, and foisted the Amazon store upon my desktop. Good luck Ubuntu ... I'm outta here.

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"I like Python, but keeping both 2 and 3 alive for so long has caused problems that make it hard to justify for serious projects."

Sounds like a strawman arguement to me. People in the community are aware of the different versions of Python and know how to deal with it. This "issue" hasn't affected Google, NASA or the millions of developers/users that utilize Python to the extent that they are in crisis mode. You can run multiple versions of Python on the same system, there are utilities that make this manageable.

What other language is "your" boss going to pick that you can't find issues with? Does he actually understand the technical details and history of said language? You can find all sorts of issues with any programming language, all of them are "Hopper complete."

Having Python 3 installed does not mean that you cannot install and use Python 2 if you wish to; if you upgrade to 13.04, your copy of Python 2.7 will remain installed, and for other users it's still in the package repositories (if it's not already installed—I'm not certain). But pushing Python 3 forwards makes sense. It is a better language and is the way forward. Having a major operating system promoting it as the primary distribution will be very helpful in continuing Python 3 adoption. I don't agree with the rest of that paragraph, either.

Then to your second paragraph—I actively enjoy using Unity. And as for the Amazon things, I see the direction they're headed in and approve of it, though the Amazon part alone is of no use to me. Canonical is making good things; sure, in the meantime there have been some things which haven't worked quite so well (e.g. I didn't find Unity usable for the first two releases) but their direction is solid, in my opinion.

I think the way the Python community handled this change is really mature compared to several other communities who've been through such change. They've done great work in making sure one single codebase can support 2.6, 2.7 and 3.2/3, Django does this.

Teams using Python to develop, in the present state, mostly base their decisions to chose py2 or py3 based on the maturity of the libraries (py3 ones) they are gonna use. Ubuntu devs are using good judgment here, they are first moving code they use for the OS from 2 to 3 and switch the default python package version. But py2 should be available to any package which specifies it as a dependency. This should be nearly invisible to a normal user. This also gives the much needed push for Py3 adoption.

Python 2 and 3 are in most practical senses two very closely related, but different, languages. So your scenario is not very different from the two groups of developers suggesting Python and Ruby.

By the way, assuming either language satisfies the external requirements for the project, any half-way competent boss would say "Figure it out. Bring me your decision by the end of the day(/week/whatever). KTHXBYE."

> Python 2 and 3 are in most practical senses two very closely related, but different, languages.

They're so closely related you can write code compatible with both (and that's the path many — if not most — libraries are taking)

ubuntu isn't deciding anything for you. both are available as packages. and the decision to introduce python 3 wasn't made by them anyway.

for new projects where i control deployment i use python 3 (these days, the support is there - in fact in at least one case i am using a python 3 only lib). for maintenance or projects where the client has existing systems, i use whatever is most appropriate.

i am a professional. i get the job done. what more is there to say? oh, yeah, running round throwing a hissy fit for internet points.

Arch has python2 and python3 with the /usr/bin/python symlinked to python3. Anything that depends on 2 uses, well, 2.

It is the bane of backwards compatibility breakage in language semantics. I sometimes think maybe Python3 should have been another language, but it is understandable when there is so little syntactic breakage between the two you want to try to tie them together than diverge on the unicode issue.

Arch made the mistake of symlinking python to python3, that's all.

Has anyone that uses Arch called it a mistake?

Yes, tons and tons of confused people popped in on all python IRC channels. Arch devs seem to think their users know everything, but there is enough evidence that not every single arch user reads all the details.

If you don't know enough to maintain your system, you shouldn't use Arch...

It is intentional. From the Archwiki [1]:

> Arch Linux targets and accommodates competent GNU/Linux users by giving them complete control and responsibility over the system.

[1] - https://wiki.archlinux.org/index.php/The_Arch_Way

I would like to amend it with "all users are required to sign a paper that says they won't bother 3rd party developers before completely understanding the arch way". Seriously, just because you think your software is used in the way X, it doesn't mean it's not used in the way Y too and maybe you should consider thinking about those people too.

yes. using "python3" to run Python 3 would have been possible without breaking existing scripts. Also you can switch your entire infrastrucutre to use "python3" without breaking anything. I don't say switching to Python 3 was to early or the worst thing in the world. I'm just not sure if changing the "python" symlink to "python3" was great.

It was confusing for a while and broke some stuff. I haven't personally experienced problems in a while though. Mistake? No. It fits in with Arch's personality and made sense. It'd have been a mistake for Ubuntu to do it at the same time ofc!

I started to specify my python preference in my #! (ie #!/usr/bin/python3) in my own programs. If everyone did this the move would be much easier.

I recommend using #!/usr/bin/env python3 as the shebang for portability[1] reasons if you intend to distribute the programs.

[1] https://en.wikipedia.org/wiki/Shebang_%28Unix%29#Portability

Thanks. Shall switch to using that.

As a full time Arch user the change was a little annoying at first but now I am perfectly happy using Python3 as the default because all my Python shell scripts and system installed packages work under Python3. I can simply work in a Python2 virtualenv when I need python2.

Agreed, I use virtualenv if I'm hacking up a website at home.

mkvirtualenv <name> --python=pythonx.y --no-site-packages

As of version 1.7 (2011), --no-site-packages is default behavior.

I still specify it every time anyway, but thought it'd be worth mentioning. :)

The --python switch is really great, though, particularly now that 3 is getting distro traction and most of us who work in Python are likely maintaining a lot of 2.x projects. Thanks!

Yes, I use Arch, and I think it was a mistake. Symlinking python to python3 breaks the assumption of virtually every Python dev out there; if you maintain an Arch package that has Python components, you usually have to sed replace the python shebangs with python2. Totally goes against Arch's normal "keep it simple" philosophy.

But, isn't it compatible with PEP 394[1]? As I see it, the mistake is to assume the `python`command links to python2.

The PEP itself should maybe point that out and not say that `python`SHOULD refer to python2 and at the same time MAY refer to python3. It only helps to the confussion.

[1]: http://www.python.org/dev/peps/pep-0394/

I've worked in environments where classic ASP, .NET 1.0, .NET 3.5 and 4.0 are all in production, some on the same server. I imagine there are similar tales regarding production environments for Java and Ruby etc. If you cannot run different versions simultaneously you have a problem. Thankfully you can.

I hope this is some sort of development/project manager rather than a business manager, otherwise they shouldn't be choosing the language at all!

Get a different boss, that one sucks.

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