net-print/hplip-3.15.2 should depend on net-print/cups without [${PYTHON_USEDEP}]. Python version optionally supported by net-print/cups is unrelated to Python version (non-optionally) used by net-print/hplip.
You may have a point here, but I think the documentation is ambiguous here or I don't understand it correctly. I hope the python team can clarify this. It says: All dependencies on other Python packages need to carry the value of PYTHON_USEDEP as a USE dependency.[1] What are python packages, everything in dev-python, all packages using the python eclasses, all with a python USE flag? It furthermore says: It must be used on package dependencies which are using the python-r1 eclass.[2] So when is PYTHON_USEDEP required? Only for dependencies using the python-r1 eclass, or for all python-*r1 eclasses? Below just for your information the dependencies of hplip whichuse any of the above mentioned eclasses: dev-python/dbus-python python-r1 dev-python/notify-python python-r1 dev-python/pygobject python-r1 dev-python/PyQt4 python-r1 virtual/python-imaging python-r1 dev-python/reportlab distutils-r1 net-analyzer/net-snmp distutils-r1 net-print/cups python-single-r1 [1] http://wiki.gentoo.org/wiki/Project:Python/Python.eclass_conversion#Metadata_variables [2] http://wiki.gentoo.org/wiki/Project:Python/python-r1#PYTHON_USEDEP
Daniel, PYTHON_USEDEP is used to enforce a match between Python versions/implementations used from dependencies. You need it only when you use the Python modules provided by dependent package.
The rule is if you actually depend on running the Python code from a package from within the same Python instance as the Python code the current package (here hplip) is using, then (and only then) you MUST use the ${PYTHON_USEDEP} dependency. If you are only using the package for its installed executables in /usr/bin, compiled C/C++/etc. libraries in /usr/$(get_libdir), etc., then you need not use the ${PYTHON_USEDEP} at all. In this case, unless I'm mistaken, hplip does not care what version of python net-print/cups and net-analyzer/net-snmp optionally support, as it doesn't use that part of the code at all. If it did, then it would *also* need to depend on USE=python on each of those packages.
+ 08 Mar 2015; Daniel Pielmeier <billie@gentoo.org> hplip-3.15.2.ebuild: + Remove PYTHON_USEDEP from net-print/cups and net-analyzer/net-snmp. Thanks to + Arfrever Frehtes Taifersar Arahesis for the report and the gentoo python team + for the detailed explanation. I took a closer look and it seems that hplip does not use python modules from cups and net-snmp. Thank you all for your help.
