pluginmanager 0.2.1

Python Plugin Management, simplified

Documentation

Source Code

Library under development. Contains rough edges/unfinished functionality. API subject to changes.

Installation

pip install pluginmanager

-or-

pip install git+https://github.com/benhoff/pluginmanager.git

Quickstart

from pluginmanager import PluginInterface

plugin_interface = PluginInterface()
plugin_interface.set_plugin_directories('my/fancy/plugin/path')
plugin_interface.collect_plugins()

plugins = plugin_interface.get_instances()

Custom Plugins

The quickstart will only work if you subclass IPlugin for your custom plugins.

import pluginmanager

class MyCustomPlugin(pluginmanager.IPlugin):
    def __init__(self):
        self.name = 'custom_name'
        super().__init__()

Or register your class as subclass of IPlugin.

import pluginmanager

pluginmanager.IPlugin.register(YourClassHere)

Add Plugins Manually

Add classes.

import pluginmanager

plugin_interface = pluginmanager.PluginInterface()
plugin_interface.add_plugins(YourCustomClassHere)

plugins = plugin_interface.get_instances()

Alternatively, add instances.

import pluginmanager

plugin_interface = pluginmanager.PluginInterface()
plugin_interface.add_plugins(your_instance_here)

plugins = plugin_interface.get_instances()

pluginmanager is defaulted to automatically instantiate unique instances.

Disable automatic instantiation.

import pluginmanager

plugin_interface = pluginmanager.PluginInterface()
plugin_manager = plugin_interface.plugin_manager

plugin_manager.instantiate_classes = False

Disable uniquness (Only one instance of class per pluginmanager)

import pluginmanager

plugin_interface = pluginmanager.PluginInterface()
plugin_manager = plugin_interface.plugin_manager

plugin_manager.unique_instances = False

Filter Instances

Pass in a class to get back just the instances of a class

import pluginmanager

plugin_interface = pluginmanager.PluginInterface()
plugin_interface.set_plugin_directories('my/fancy/plugin/path')
plugin_interface.collect_plugins()

all_instances_of_class = plugin_interface.get_instances(MyPluginClass)

Alternatively, create and pass in your own custom filters.

def custom_filter(plugins):
    result = []
    for plugin in plugins:
        if plugin.name == 'interesting name':
            result.append(plugin)
    return result

filtered_plugins = plugin_interface.get_instances(custom_filter)

class FilterWithState(object):
    def __init__(self, name):
        self.stored_name = name

    def __call__(self, plugins):
        result = []
        for plugin in plugins:
            if plugin.name == self.stored_name:
                result.append(plugin)
        return result

Architecture

pluginmanager was designed to be as extensible as possible while also being easy to use. There are three layers of access.

Interfaces:

public facing

Managers:

extended or replaced

Filters:

implementation specific

Interface

An interface was used to provide a simple programmer interface while maintaining the ability to separate out the concerns of the implementation. The main interface is the PluginInterface. PluginInterface is designed to be as stateless as possible, and have interjectable options where applicable.

Managers

There are four managers which make up the core of the library.

DirectoryManager:

Maintains directory state. Responsbile for recursively searching through directories

FileManager:

Can maintain filepath state. Does maintain file filter state. Responsible for applying file filters to filepaths passed gotten from directories

ModuleManager:

Loads modules from source code. Keeps track of loaded modules. Maintains module filter state. Responsible for applying module filters to modules to get out plugins.

PluginManager:

Instantiates plugins. Maintains plugin state.

Filters

Filters are designed to offer implementation-level extensiblity. Want to only return only files start with “plugin”? Create a filter for it. Or use some of the provided filters to provide the desired implementation.

All filters are callable.