Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Nick Sarbicki <nick.a.sarbicki@gmail.com>
Newsgroups: comp.lang.python
Subject: Basic plugin architecture
Date: Wed, 06 Apr 2016 09:05:10 +0000
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Hi,

Question on how people here would design a basic plugin architecture:

I'm playing with the idea of having a pluggable system where the users can
create some simple classes which can then be accessed in a Django app.

I want to make it as __simple__ as possible for the user. Hopefully to the
point of being able to make a .py file and then drag and drop it into the
plugins folder. The result should be a dropdown later on with the list of
available classes.

Providing the list of classes once imported should be simple.

Actually importing the classes dynamically has caused a few issues.

I have a solution but wanted to know if anyone had better ideas.

Folder structure is:

=E2=94=9Crun.py
=E2=94=94loader/
  =E2=94=9C=E2=94=80plugins/
  =E2=94=82 =E2=94=9C=E2=94=80__init__.py
  =E2=94=82 =E2=94=9C=E2=94=80plugin1.py
  =E2=94=82 =E2=94=94=E2=94=80plugin2.py
  =E2=94=9C=E2=94=80__init__.py
  =E2=94=9C=E2=94=80models.py
  =E2=94=9C=E2=94=80views.py
  =E2=94=94=E2=94=80etc.py

My current solution is:

########loader/plugins/__init__.py########
> import glob
> import importlib
> import os
>
> def is_valid_plugin(plugin):
> return os.path.isfile(plugin) and not
os.path.basename(plugin).startswith('_')
>
> package =3D 'loader.plugins'
>
> plugins_to_import =3D [plugin for plugin in
glob.glob(os.path.dirname(__file__) + '/*.py') if is_valid_plugin(plugin)]
>
> plugins =3D [importlib.import_module('.' + os.path.basename(plugin)[:-3],
package) for plugin in plugins_to_import]

In relative terms I'm looking at the packages from the same position as
run.py, so would import as:

> from loader import plugins

plugins.plugins would then be a list of imported plugin modules.

With this I can use the __dict__ of each plugin module in plugins.plugins
to find which classes we want to use.

This works. But I wonder if there is a better way.

Any suggestions?

- Nick.