[gentoo-user] How to get rid of Python2 (where possible)

[Helmut Jarausch]

Hi,

would anybody please explain Portage's technique for selecting Python  
versions for packages
from dev-python and similar.

I'd like to set up things such that Portage installs only the  
Python-3.{3,4} version unless the
packages doesn't support Python-3.x

Currently I have

PYTHON_COMPAT="python2_7 python3_3 python3_4"
PYTHON_TARGETS="python2_7 python3_3 python3_4"
# PYTHON_SINGLE_TARGET="python2_7"
PYTHON_SINGLE_TARGET="python3_3"

in my /etc/portage/make.conf and portage itself is Python3-based.
I have to toggle the two PYTHON_SINGLE_TARGET lines depending
on some packages, e.g., dev-util/eric requires
PYTHON_SINGLE_TARGET="python3_3"
which causes other packages not to install.

I have tried to remove python2_7 from PYTHON_TARGETS but then
I cannot re-install portage although it is based on Python3.

As you can see I am lost?

Many thanks for shedding some light onto these issues,
Helmut