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Let's check the package "python" in Ubuntu... 14.04 (2014): Python 2 16.04 (2016): Python 2 18.04 (this is obvious but... less than 12 months ago!): you gues

by j1elo 8y ago

Let's check the package "python" in Ubuntu... 14.04 (2014): Python 2 16.04 (2016): Python 2 18.04 (this is obvious but... less than 12 months ago!): you guessed it, Python 2 (!!!) So, still in 2018 and until 2020 (when I guess the next LTS release of Ubuntu is scheduled) all instructions over the internet telling you to run "python" or "pip install" will run Python 2 if copied into your Ubuntu terminal. I already said this in a previous discussion about Python 2 vs. 3: what a lost opportunity.

acqq 8y ago
You should assume that python means “2” and python3 what it says in the name. The bigger problem is that invoking “python3” and having a script developed for “python3” still doesn’t guarantee that the script will work, there were incompatible changes during python3 history.
- ThatPlayer 8y ago
  Arch Linux has the packages the other way around: the 'python' package is Python 3 while there is a python2 package and binary. I guess Ubuntu has it that way to stop the breaking changes however
  - detaro 8y ago
    You should expect python to be Python 2 because that's the official recommendation, for compatibility: https://www.python.org/dev/peps/pep-0394/ https://www.python.org/dev/peps/pep-0394/ New code has no problem explicitly requesting python3, old code needs changing to request Python 2, but if you touch it anyways it's of course safer to make that change.
    - Macha 8y ago
      In case anyone thinks Arch is being crazy here and ignored the PEP (and doesn't read the PEP), note the change here was written in 2011 and approved in 2012 based on Arch's experience moving to python 3 by default in 2010.
- slondr 8y ago
  #!/usr/bin/env python3
- VWWHFSfQ 8y ago
  there were incompatible changes during python2 history as well. RHEL shipped Python 2.4 forever, and now ships 2.7. There are many breaking changes between those two versions.
- joshuamorton 8y ago
  This has always been true. New syntax or libraries were added in almost every major Python version. If python2 was python2.2, it wouldn't support `with`. It's just that python2 has been Python 2.7 for a decade, so it's been relatively stable.

by j1elo 8y ago

acqq 8y ago

You should assume that python means “2” and python3 what it says in the name. The bigger problem is that invoking “python3” and having a script developed for “python3” still doesn’t guarantee that the script will work, there were incompatible changes during python3 history.

ThatPlayer 8y ago
Arch Linux has the packages the other way around: the 'python' package is Python 3 while there is a python2 package and binary. I guess Ubuntu has it that way to stop the breaking changes however
- detaro 8y ago
  You should expect python to be Python 2 because that's the official recommendation, for compatibility: https://www.python.org/dev/peps/pep-0394/ https://www.python.org/dev/peps/pep-0394/ New code has no problem explicitly requesting python3, old code needs changing to request Python 2, but if you touch it anyways it's of course safer to make that change.
  - Macha 8y ago
    In case anyone thinks Arch is being crazy here and ignored the PEP (and doesn't read the PEP), note the change here was written in 2011 and approved in 2012 based on Arch's experience moving to python 3 by default in 2010.
slondr 8y ago
#!/usr/bin/env python3
VWWHFSfQ 8y ago
there were incompatible changes during python2 history as well. RHEL shipped Python 2.4 forever, and now ships 2.7. There are many breaking changes between those two versions.
joshuamorton 8y ago
This has always been true. New syntax or libraries were added in almost every major Python version. If python2 was python2.2, it wouldn't support `with`. It's just that python2 has been Python 2.7 for a decade, so it's been relatively stable.