What is a Plugin?

Before writing your first plugin, you may want to know what is a plugin, how is it made, and what are the best solutions for your needs. In this chapter we’ll cover what is a plugin, what you can do with them, and some vocabulary.

You may want to skip ahead to Anatomy of a plugin if you already know what a plugin is and what types of plugin there are.

Plugin Types

There are four types of plugins: Single file plugin, Folder plugin, Namespace package plugin, and Entry point plugin.

Single file

A Single file plugin is the most basic form a Sopel plugin can take. It is composed of a single file available to Sopel from its plugins directory (or from one of its extra directories). You can write a single file plugin when:

• everything is in a single file

• either:

  • dependencies are limited to Sopel and Python’s built-in library; or

  • your plugin is a “one-off” for your use only (not intended to be shared)

This type of plugin is easy to install: copy its file into the right location, and Sopel will load it on startup.

Note

You can still use extra dependencies with a single file plugin. Bot owners will have to install them manually, so you should probably document them, and possibly list them in a requirements.txt file to be used with pip install -r if you want to simplify the installation process.

Folder

A Folder plugin is a folder that contains a __init__.py file. It is available to Sopel the same way a Single file plugin is, and shares the same warnings/advice:

• everything that is not available in this __init__.py file won’t be visible to Sopel

• either:

  • dependencies should be limited to Sopel and Python’s built-in library, for ease of installation; or

  • the plugin is a “one-off”, not intended to be shared

By default, Sopel’s plugin directories are not available in sys.path, so it is not possible to do from my_plugin_dir import some_module without a specific configuration from the bot’s owner.

When a plugin author wants to split code into different files, and/or share it between multiple plugins, the best option is to use an Entry point plugin instead.

Note

Just like single file plugins, you can use extra dependencies with folder plugins; the same advice about requirements.txt and pip applies.

Namespace package

A Namespace package plugin is a Python namespace package, using the namespace sopel_modules. It must be installed in the Python environment to be used by Sopel, and can require Python dependencies.

Given a sopel_modules.plugin plugin, Sopel will load everything that is available from the sopel_modules/plugin/__init__.py file.

It is the initial version of Sopel’s packaged plugins: it can be packaged and uploaded to PyPI then installed using pip install.

When a plugin author wants to distribute a Sopel plugin, the best option is to use an Entry point plugin instead.

Entry point

New in version 7.0.

An Entry point plugin is a Python module or package distributed via a setup.py script, and it is available to Sopel via Sopel’s sopel.plugins setup entry point.

Given this definition of an entry point from a setup.cfg file:

[options.entry_points]
sopel.plugins =
    my_plugin = package_name.my_plugin_file

Sopel will load everything available from the package_name.my_plugin_file Python module under the plugin name my_plugin. It means that you can have any package name and any module name as long as it is a valid Python module and as long as you properly define the entry point.

You should write an entry point plugin when:

• you want to distribute your plugin on PyPI

• you want to split the code in multiple files

• you have dependencies beyond Sopel and Python’s standard library

• you want a modern and reliable way to package your Sopel plugin

• you want to distribute more than one Sopel plugin per distributed package

An entry point plugin is the best, most flexible way to package and distribute a Sopel plugin (or collection of plugins) in a clean, easy-to-update manner.

Note that a single Python distributed package can expose more than one Sopel entry point plugin, which is great to bundle multiple plugins at once.

See also

The Python Packaging Authority explains how entry points work and how to use them in its Entry points specification.

Naming plugins

Sopel plugins conventionally have all-lowercase names, usually one word. However, sometimes multiple words are needed for clarity or disambiguation; snake_case is normally used for these.

How Sopel determines a plugin’s name depends on what kind of plugin it is:

Single file

The file’s basename (e.g. plugin in plugin.py)

Folder

The folder name (e.g. plugin in ~/.sopel/plugins/plugin/__init__.py)

Namespace package

The submodule name (e.g. plugin in sopel_modules.plugin)

Entry point

The entry point name (e.g. plugin in plugin = my_plugin.module.path)