the correct way to install python packages as non root user in non default path

[News123]

Hi,

I'm having an Ubuntu host, but want to (experimentally)
install some modules, which are newer than the Ubuntu ones
(distros lag always a little behind and some tools need newer versions.)


What would be a clean way to do this?
I want to be sure, that any 'special hacks' on my host are cleanly
separated from the default installation.


I thought about installing some newer packets for example under
/opt/newpymods  # or any other name
and change the python path such, that modules will first be searched
there and only then in the default path.


Is this a viable approach?

How exactly would I have to set PYTHONPATH?

I'm asking, as I had some problems installing a new version of coherence.

What I did:

##### download a newer version of Coherence
cd /downloads
svn co https://coherence.beebits.net/svn/tags/Coherence-0.6.2 Coherence

#### create a new directory for all 'newer' python modules
mkdir -p /opt/newpymod
export PYTHONPATH=/opt/newpymod
python setup.py install --prefix /opt/newpymod
### this fails, so I'll adapt PYTHONPATH
export PYTHONPATH=/opt/newpymod/lib/python2.5/site-packages
mkdir -p /opt/newpymod/lib/python2.5/site-packages
### now I get quite some error messages

> running install
> running bdist_egg
> running egg_info
> writing requirements to Coherence.egg-info/requires.txt
> writing Coherence.egg-info/PKG-INFO
> writing top-level names to Coherence.egg-info/top_level.txt
> writing dependency_links to Coherence.egg-info/dependency_links.txt
> writing entry points to Coherence.egg-info/entry_points.txt
> package init file 'misc/__init__.py' not found (or not a regular file)
> Traceback (most recent call last):
>   File "setup.py", line 124, in <module>
>     setup(**setup_args)
>   File "/usr/lib/python2.5/distutils/core.py", line 151, in setup
> . . .


thanks in advance for any help