[Python-apps-team] Doubt about developing plugins for python applications

[BRAGA, Bruno]

Dear Gurus,

I have a question about plugins structure, and I would like to get some
advise from you.

I have an application to which I would like to add some external plugins,
that will be essentially part of the application, thus using its existing
modules, but adding functionality to the main application. For that, I
designed the following structure:

program/
    |
    |---- program.py
    |
    |---- programlib/
    |
    |---- setup.py
    |
    |---- plugins/
    |         |

where program.py is the application entry point, which uses the programlib
package, and so the plugins. The plugins have access to all
packages/modules within programlib and to their own directory tree.

In this sense, the programlib is shared by the main program and its
plugins, but it is still private to the rest of python.

When compiling/building the source with setup.py, I encountered the problem
that separating the plugin as an independent solution:

program/
    |
    |---- setup.py
    |
    |---- plugins/
    |         |
    |         |--pluginA/
    |         |

the setup.py fails (obviously) because it does not find the
packages/modules from programlib, which are only available to the main
application source.

Installing program from source, the setup.py places the files under
/usr/local/lib/dist-packages, making programlib accessible to the
program-pluginA setup.py. But as being an application, the debian packaging
will install it into /usr/share/program, so the compilation of the plugin
will fail.

Long story short, I guess my question is: what would be the best way to
overcome this problem? I can see a couple of workarounds, but I do not know
the best approach, or if there are alternatives to what I have in mind. I
could think of:

a) make the package programlib public (meaning storing the files in
pymodules/dist-packages) - but this does not seem good solution, because it
does not have any need for programlib to be accessible by all python code

or

b) add current installation to python path (eg. /usr/share/program) so the
plugin can import the programlib packages/modules.


What would you suggest me to do?

Thank you for your help.

--
*Braga, Bruno*
www.brunobraga.net
bruno.braga at gmail.com
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