ROOT dependency from the python virtualenv selected during ROOT installation

[malfonsi79]

Hi all,

I remember that, at least years ago, a ROOT installation built from source was strictly dependent on the python executable that was passed (or automatically found) by cmake (or configure in the Ancient Age).

Is it still the case? Is it only the python executable or also the libs and the site-package? What is the role of the PYTHONPATH in this? (Although I guess this env variable tells just where to find the packages…)

I explain my case: I have to build ROOT on top on two python3 virtualenv stacks that differ only by a few packages versions and I would like to avoid to duplicate the ROOT installation. Note also that the python executable is the same for both virtualenv, a copy (because I prefer the option --always-copy when creating the virtualenv) of the Debian 12 system python.

So the question is if I can use the same ROOT installation for both python3 stacks. (At the moment it seems to work but not sure if I have maybe not yet hit the sensible cases)

I look forward to your reply,
Matteo

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ROOT Version: any latest version (>= 6.34)
Platform: Debian 12
Compiler: gcc 12.2

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[lbreitwi]

Hi @malfonsi79,

Thank you for your question.
@bellenot could you please take a look it?

Lukas

[bellenot]

Hi, no idea, I have no experience with PyROOT and virtual environments. Maybe @vpadulan know better?