ExtremePluginManager 1.1.3

A powerful library for managing plugins in your Python application.

Extreme Plugin Manager

A library for effortlessly enabling and managing plugins in your Python application.

This library provides you with complete control over which objects your plugins can and can not access.

Additionally, this library provides powerful tools such as the ability to reroute all plugin STDOUT and easily spawn different types of background tasks.

Contents

• Installation
• Usage
  • The ExtremePluginManager Class
  • The Plugin Class
  • The BaseThread Class
  • Plugin Conversions
• Plugin Creation Guide
  • Rerouting STDOUT
• Limitations

Installation

pip install ExtremePluginManager

Usage

To start, you will simply need to instantiate the ExtremePluginManager class like so:

import ExtremePluginManager

manager = ExtremePluginManager.ExtremePluginManager("plugins")

The ExtremePluginManager Class

This class takes one mandatory, and several optional parameters.

• plugin_directory: path - The path to where plugins are to be stored (mandatory)
• create_dir: bool = False - If the plugin directory does not exist and this is True, it will be created, otherwise ValueError will be raised.
• plugin_register_filename: str = "plugins.json" - The name of the file to track which plugins are installed/enabled. This is automatically created in the plugin_directory
• start_event: str = "on_start" - The name of the plugin function which will be triggered when the plugin is loaded. This event is managed automatically.
• end_event: str = "on_stop" - The name of the plugin function which will be triggered when the plugin is unloaded/stopped. This event is managed automatically.
• builtin_funcs: dict = None - A dictionary of custom builtin values to pass into each plugin. The key is the code reference name and the value is the object itself. These values can be variables or pointers to functions. Plugins can not access any objects from your project outside this dictionary.

The ExtremePluginManager class also contains helpful methods. Please only use getters/setters to update properties instead of the private attributes (prefixed with an underscore _):

• reload_plugins() - Reloads all plugins from disk and triggers the start_event. This can be a useful tool for plugin developers as they can reload their plugin from inside your app instead of needing to close and re-open each time.
• on_plugin_load(plugin) - This is an event which can be overridden. Each time a plugin reads the code file from disk and executes, this event is triggered.
• execute_event(event: str, *args, **kwargs) - Calls the function event in each plugin and passes in the *args and **kwargs parameters. This is how you trigger different plugin events. Plugins do not need to implement all of these functions, but you should keep a list of the available functions for your documentation.
• execute_end_event() - Triggers the end_event event for all plugins
• execute_start_event() - Triggers the start_event event for all plugins
• search_by_id(plugin_id: str) - Returns the plugin (as a Plugin object) with the corresponding plugin_id (set in the plugin config file)
• search_by_attribute(info_attribute: str, value, default=None) - Returns a list of plugins (as a Plugin object) which have the attribute info_attribute with the value. Use default for a default value in the event not all plugins will have the attribute
• install_plugin(path: path, enable: bool = True, overwrite: bool = True) - Installs the plugin at the specified path to the plugin directory. If enable is True then the plugin will also be enabled and start_event will be triggered. If overwrite is set to False and a plugin already exists with the same name, an exception will be raised.
• uninstall_plugin(plugin_id: str, remove_files: bool = True) - Uninstalls a plugin with the ID plugin_id. If remove_files is True then the files will be deleted as well (this can not be undone). If False then the plugin file will remain but would have been removed from the registry so will not load until it is installed once again.
• create_template_plugin(plugin_id: str, enable: bool = True) -> str - Creates a template plugin in the directory format. Both the filename and plugin ID will be set to plugin_id. If enable is True then the template plugin will also be enabled. The full path to the plugin will then be returned.
• enable_plugin(plugin_id: str) - Marks the plugin with the ID plugin_id to enabled and triggers the start_event event
• disable_plugin(plugin_id: str) - Marks the plugin with the ID plugin_id to disabled and triggers the end_event event
• set_plugin_state(plugin_id: str, state: bool) - Marks the plugin with the ID plugin_id to state and triggers the corresponding event
• get_plugin_register() - Returns the current state of the plugin register
• get_plugin_directory() - Returns the path to the directory where the plugins are kept

The Plugin Class

A plugin can be in a few different formats but regardless of the format, the Plugin class exposes the same methods. Most of these methods are also available to the plugin code. You can obtain this instance by using one of the search functions in the ExtremePluginManager class

• reload() - Reloads the plugin code but DOES NOT trigger the start_event
• read_file(self, path: path, encoding: str = "utf-8") -> str - Reads the file located at path and returns the contents as a string (decoded with encoding - used for plaintext files). Note that path should be relative to the root directory of your plugin.
• read_file_bytes(self, path: path) -> bytes - Reads the file located at path and returns as bytes (used for binary files). Note that path should be relative to the root directory of your plugin.
• write_file(self, path: path, contents: str, encoding: str = "utf-8") - Writes contents to the files (encoded using encoding) to the file located at path. Note that path should be relative to the root directory of your plugin.
• write_file_bytes(self, path: path, contents: bytes) - Writes contents into the file located at path (used for binary files). Note that path should be relative to the root directory of your plugin.
• remove_file(self, path: path) - Removes the file located at path. Note that path should be relative to the root directory of your plugin.
• execute_event(event: str, *args, **kwargs) - Executes the plugin function called event passing in *args and **kwargs
• kill() - This method prevents the plugin from having future events triggerd and will no longer be visible to plugin searches. This will trigger the end_event

The BaseThread Class

This class extends the threadding.Thread class but has three additional methods. This class is created when a plugin calls one of start_background_task, start_delayed_task, or start_interval_task.

• get_name() -> str - Returns the name of the thread
• set_name(name: str) - Sets the name of the thread
• kill() - Terminates the thread immediately by raising a ThreadKilledException

Plugin Conversions

Plugin formats can easily be converted between each other. The following conversion functions are availible:

import ExtremePluginManager

# convert directory format to zip format
# you can optionally specify `zip_format` parameter to set the resulting format
# can be "zip", "tar", "gztar","bztar", or "xztar".
ExtremePluginManager.converter.directory_to_zip("src_directory", "dst_zip")

# convert zip format to directory format
ExtremePluginManager.converter.zip_to_directory("dst_zip", "src_directory")

Plugin Creation Guide

It should be noted that the end_event is automatically triggered when the application terminates.

In addition to the builtins you have provided in the constructor, the following builtins are available by default.

• read_file(self, path: path, encoding: str = "utf-8") -> str - Reads the file located at path and returns the contents as a string (decoded with encoding - used for plaintext files). Note that path should be relative to the root directory of your plugin.
• read_file_bytes(self, path: path) -> bytes - Reads the file located at path and returns as bytes (used for binary files). Note that path should be relative to the root directory of your plugin.
• write_file(self, path: path, contents: str, encoding: str = "utf-8") - Writes contents to the files (encoded using encoding) to the file located at path. Note that path should be relative to the root directory of your plugin.
• write_file_bytes(self, path: path, contents: bytes) - Writes contents into the file located at path (used for binary files). Note that path should be relative to the root directory of your plugin.
• remove_file(self, path: path) - Removes the file located at path. Note that path should be relative to the root directory of your plugin.
• info() - Returns a dictionary representing the contents of the plugin's info.json
• plugin_manager - An attribute which is a reference to the ExtremePluginManager which contains this object
• plugin - An attribute which is a reference to the actual Plugin class instance
• start_background_task(target: callable, *args, **kwargs) - Calls the function target (please only pass in function references) with the parameters *args, and **kwargs to be run asynchronously
• start_delayed_task(delay: float, target: callable, *args, **kwargs) - Calls the function target (please only pass in function references) with the parameters *args, and **kwargs to be run asynchronously after delay seconds have passed
• start_interval_task(interval: float, target: callable, *args, **kwargs) - Calls the function target (please only pass in function references) with the parameters *args, and **kwargs to be run asynchronously every interval seconds

Rerouting STDOUT

If you add a builtin with the reference name of print which takes the parameters *args, sep=' ', end='\n', file=None then all calls to print will be sent here instead of the default function. You can then do what you wish with the output.

Limitations

If you attempt to reference a builtin value for your plugin with an IDE such as PyCharm, it will flag the value as unknown. This is because we inject these values into the Python compiler at runtime.