Will Python3 be default?

I find the precompiled ROOT binary distributions rather useful (especially for CI/CD). However, I haven’t been able to take advantage of them for a few years now, as they do not come with Python3 PyROOT baked in, only Python2.

Python2 is EOL since the beginning of the year, but I see the current newest version 6.20/00 - 2020-02-26 still relies on Python2. I can compile ROOT with Python3 support just fine, but it would be nice not having to compile it myself. Do you plan to switch to Python3 at some point, and if so, do you have a timeline?

Best regards,

Well, what do you mean by “system default python version”? Is it what the symlink /usr/bin/python points to? Because, e.g., Ubuntu 20.04 doesn’t have that symlink at all. So what is the “system default python version” there?

sudo apt-get install python; python --version

You don’t understand - there is no python package in Ubuntu 20.04 and there is no symlink named python. There are only python2 and python3 packages and symlinks.

@Axel So, I assume the “default” will be “python3” on Ubuntu 20.04 LTS.

OK, thanks for the info.

We are now working on multi-python ROOT builds, the feature is mostly implemented and should be merged in master soon. This means that you will be able to build ROOT for both Python2 and Python3 in a single build.

This also means that we could potentially distribute binaries that are built against both Python2 and Python3, if the target system has both.

Sounds great. Thanks for the info.

…and (also to answer @Wile_E_Coyote’s question): we look for Python3, we look for Python2, and we’ll build for both. TPython will default to use python3 if found (or python2 if not). @etejedor do I remember this correctly?

@Axel yes that is correct.

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