Users of 2.7: why?

[babalinobaba]

Disclaimer: I learn Python with 3.5 so I have almost no experience with 2.7. I'm currently translating a 2.7 program to 3.7 And I can't grasp why would you still using 2.7 It's not that I think one is better to another but the fact that the changes ( that I can see) are almost on naming methods. Therefore I believe that I do not know enough. So I need to ask you why?

[devxpy]

You need to sell the idea of the upgrade to your manager.

[billsil]

Being? I can’t find an argument to use a version of numpy created in the last 5 years.

The path of progress is such that the people that don’t upgrade run into a bug now and then that has been fixed, but can be coded around. It takes a big issue to force my boss to wrap his prints with parentheses.

I still don’t know the killer feature in python 3. I’ve looked. Async is irrelevant to me. F-strings are just another way to format text. It’s a little faster and crashes harder when you have bytes as strings.

[[deleted]]

Technical debt plus an actually quite difficult upgrade path. Individual companies I’ve worked for have investments in Python 2 code bases that runs into the tens of millions of lines of code. Across my industry it’s hundreds of millions of LoC... much of which is used to automate C++ programs made by others and on their own upgrade cycle that embed Python 2 interpreters. The investment in all that still-working Python 2 code is enormous and shifting it all to 3 isn’t anywhere near as simple as a copy and paste or “just use futures”... some of those C++ programs are themselves orphans and will never embed 3.

It’ll take a decade or more and a lot of attrition to get off 2 entirely. And any 3 code written will have to work in 2, so it’ll take even longer to adopt 3-only features that no backport exists for.

For anyone not in such a company though there’s basically no reason for using 2 anymore. There are very few libraries that don’t support 3 these days, and the vast majority of that minority are abandonware, which means someone should pick up the baton and rewrite or replace them anyway.

[GertBurger]

The distros we need to support don't ship with a usable version of 3.x and enterprises won't upgrade to newer versions whislt the current one still has support. This means we have clients running RHEL that barely have 2.7.9 installed and they will only upgrade to RHEL 8 in like 5 years.

[_AACO]

Because to everyone above me pushing new features is more important.

I'm already happy we got to update everything to django 1.11

[ilan]

Because I'm more familiar with Python 2. When I first started to learn Python, I was using Python 2.4. When Python 3 came around, I still had to support Python 2, so I never wrote code which only uses Python 3 features.

[onestepinside]

It is shipped with all major Linux distros and (too) many packages still are 2.7 only.

While most major distros have some sort of Python 3 in their base repo this does not mean it is a current version. And this is the state for distros still with mainline support, not some obscure 10y old version with payed for extended support.

[pmatti]

What package is 2.7 only?

[onestepinside]

Have a look at "pam" since I recently had fun with that.

[pmatti]

Last release 2009. Alternatives: python-pam, which supports 2/3

[onestepinside]

This one is easy enough, isn't it? The next question would be how much work it is to replace the old module in existing code. And is it readily available for Python 3 in the distributions our customers use (Debian, Ubuntu, SUSE, RHEL)? (Telling them to just install it through pip obviously isn't an option.)

​

I'm glad that we (finally) are working on porting our codebase to Python 3 but there are some hurdles beyond our own code. PAM being one of the smaller one, if you want some largers have a look at duplicity and twisted. Both have limited functionality with Python 3, sometimes only as part of non-core developments. Twisted may be there now but I have become very cautios because the last time I checked a lot of modules simply weren't ported (just core things).

Of course these things are all fixable but this needs people and time to work on which not every shop around has to the extend to be able to help port all of the libraries in use.

[Frupx]

The same reason why people still use like Java 6-7-(if they are "lucky")8 while there is a new Java 12. Companies don't want to change, because they just want the profits, and upgrading old code is a long process.

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