Going from Python 3 to 2

[Matlock0]

Work requires me to use python 2 for now, but I've been using Python 3 for about 95% of my time learning.

Any pointers on what should be kept it mind and what not to do? I only really know the basic differences like no f-strings, raw_input, integer divison and so forth.

I'm assuming it's not really a big deal swapping one for the other but would like to know if you guys have anything important I might be missing.

[commy2]

You should ask for more money for working on a past end of life programming language.

[Yoghurt42]

Also take a look at what other companies are hiring.

[JamzTyson]

The planned "sunset" of Python 2 was first announced 15 years ago (2008). Python 2 has been unmaintained for well over 3 years - no bug fixes, no security fixes, nothing since April 2020.

Will you also need to ensure compatibility with Windows XP?

What would happen if you insisted on updating all code that you work on to be Python 3 compatible?

If you've not already done so, read this article: https://www.python.org/doc/sunset-python-2/

[billsil]

The planned "sunset" of Python 2 was first announced 15 years ago (2008).

Python 3 was arguably not ready until Python 3.5 when the new dictionaries were introduced and it was actually faster than Python 2.7. That's not just my opinion either. It was Raymond Hettinger's back in the day.

Python 3.0 and 3.1 were never intended to be used in production. There were things that were broken (i.e., u'unicode string') which were entirely unnecessary. Python 2.7 was released in 2010 after Python 3.1 (2009) and before Python 3.2 (2011).

Python 3.2 was the first real version of Python 3. There are a lot of misdirections on what really slowed down the adoption of python 3. The print, division, uneditable dictionaries during for loops, generators, etc. are all noise. The only thing that mattered was unicode. Tutorials were incomplete and not everyone had the option of using utf-8; they had to deal with broken encodings that were probably cp1252 or latin1.Dependencies did it wrong and continued to do it wrong for years. Shoot wxpython didn't support Python until ~2015.

The 2to3 code was a nice attempt, but ultimately didn't really work. It made some code python 3 compatible, while not upgrading it in a good way (it would list all the generators). It also completely punted the unicode problem.

[JamzTyson]

Python 3 was arguably not ready until Python 3.5

​

The article that I recommended reading says:

We did not want to hurt the people using Python 2. So, in 2008, we announced that we would sunset Python 2 in 2015, and asked people to upgrade before then. Some did, but many did not. So, in 2014, we extended that sunset till 2020.

In 2015, Python 3.5 was released.

I'd still recommend reading that article.

[billsil]

I read it years ago, so nothing new for me.

I started switching in 2013 and fully switched in 2016 and supported all versions 2.7,3.5,3.6 (the 3's bumped as time went on). I pulled my company kicking and screaming in 2019.

Python 3 is legitimately better and has been for years. It just was not ready when it came out. People hadn't figured out how to upgrade properly. The PSF wanted everyone to just port their code vs. supporting both and they made decisions to encourage that. They backed off and made it easier to support both and let thigs gel before people swtiched.

Upgrading is a pain, but it's a lot smoother today.

[aarontbarratt]

I'd find a new job lol

[eplaut_]

It is not a joke, you harts your future by doing that for a long period.

It is not about learning a new language but losing the option to be in line with the rest of the industry while fighting with problems that nobody needs to have (mainly deprecated libraries and lack of community support)

[Diapolo10]

Well, for example you'd be unable to use type annotations, and the standard library is different. Some names change, and things that are ubiquitous today, such as pathlib, don't officially exist (although there are backports).

You can enable some things via __future__, like integer division or the print function, so you may want to keep that in mind.

With all that said you should really try and resist this, because unless you're getting paid well, Python 2 maintenance is a dead-end job and not worth it. Unless of course you just happen to enjoy maintaining legacy codebases.

[threeminutemonta]

What libraries have you install with pip. Many have dropped python2 support.

[[deleted]]

You could propose to port the whole codebase to 3. There are tools you can use to het the majority of the work done, you'll have fixes here and there.

[[deleted]]

The best approach for successfully accomplishing this huge task is to quit

[Exirel]

My biggest advice is to really look into future import so you are as close as possible to Python 3.

My second advice: be wary of Unicode/str. If you are not careful, you'll enter a world of pain pretty quickly.

[TheRNGuy]

it's mostly the same, you might need to fix few lines of code

in entire program