RFC: default python installlation directories

[Jacek Konieczny]

Hi,

Most Python HOWTOs and similar resources suggest using 'pip',
'easy_install' or other tools to install python modules or python-based
programs. The problem is, that in PLD those tools would install modules
in /usr/{lib{64},share}/pythonX.Y/site-packages – the same place, where
python modules from our RPM packages go.

This is a mess and may destroy already installed packages – using pip to
install a single innocent program may cause chain reaction of installing
dependency modules and overwitting old versions of those already in the
system.

virtualenv can help, but only if one chooses to use it.

I suggest patching python, python3 and, if neccessary, other packages,
so distutils/setuptools/pip would install Python modules to /usr/local
by default – like autoconf configure scripts do. Python would look for
modues in /usr/local first and then in /usr.

Effects:

1. easy_install/pip/etc  would not overwrite distribution packages –
that is what we want.

2. modules installed with easy_install/pip/etc would override those
installed from RPM – that is what the user would expect installing
something manually.

3. No existing python-*.spec would build any more.

All python specs would need to be updated to force proper instalation
directories. I would prepare %setup_py2 and %setup_py3. Those would use
proper python interpreter and compiler flags too.

I guess a 'sed' job on all the python-*.spec would do the trick for most
packages.

4. Existing packages (except, maybe, a few exceptions, like pip itself
would not have to be rebuilt immediately – the paths used by the
packages would still be ok

What do you think?

Jacek