Local Collection Of Python Packages: Best Way To Import Them?

I need to ship a collection of Python programs that use multiple packages stored in a local Library directory: the goal is to avoid having users install packages before using my pr

Solution 1:

Messing around with sys.path() leads to pain... The modern package template and Distribute contain a vast array of information and were in part set up to solve your problem.

What I would do is to set up setup.py to install all your packages to a specific site-packages location or if you could do it to the system's site-packages. In the former case, the local site-packages would then be added to the PYTHONPATH of the system/user. In the latter case, nothing needs to changes

You could use the batch file to set the python path as well. Or change the python executable to point to a shell script that contains a modified PYTHONPATH and then executes the python interpreter. The latter of course, means that you have to have access to the user's machine, which you do not. However, if your users only run scripts and do not import your own libraries, you could use your own wrapper for scripts:

#!/path/to/my/python

And the /path/to/my/python script would be something like:

#!/bin/sh
PYTHONPATH=/whatever/lib/path:$PYTHONPATH /usr/bin/python $*

Solution 2:

I think you should have a look at path import hooks which allow to modify the behaviour of python when searching for modules.

For example you could try to do something like kde's scriptengine does for python plugins[1]. It adds a special token to sys.path(like "<plasmaXXXXXX>" with XXXXXX being a random number just to avoid name collisions) and then when python try to import modules and can't find them in the other paths, it will call your importer which can deal with it.

A simpler alternative is to have a main script used as launcher which simply adds the path to sys.path and execute the target file(so that you can safely avoid putting the sys.path.append(...) line on every file).

Yet an other alternative, that works on python2.6+, would be to install the library under the per-user site-packages directory.

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[1] You can find the source code under /usr/share/kde4/apps/plasma_scriptengine_python in a linux installation with kde.