# Addon System

This is a fully rewritten RelativeAddonsSystem [PyPi] [GitHub]

What is it?

This is super useful (or useless. Depends on your mood) thing ever!

This is a library that allows you to manage "addons" in your project.

You want to install only one library? Just do it!

It has no third-party dependencies!

What is addon?

Beneficial thing!

Addon is a mini-project(usually independent) that provides an interface for your main project and can be used as a part of it.

Addon is a directory that contains at least two files:

Addon metafile
Addon main module

Addon metafile

Is a JSON formatted file. That consists of these values:

id - string. Addons must have unique id. Usually consists of your username and addon name: KuyuGama/SomeAddon
name - string. Name of addon. Can be used for frontend display
module - string. Main module of addon
authors - array[string]. Author names of addon
version - [optional] string. Version of addon(usually SemVer)
description - [optional]string. Description of addon. Can be used on frontend
depends - [optional]array[string]. Addon dependencies. Format is library==version (such as pip). If you are using your own library managing class, you can change a string format to yours.
extra - [optional]object. Addon extra info. Used to store custom values that can be changed in runtime.

Addon module

Is a standard python module! The only exception is an interface that will use your main code of project.

I've been inspired by a plugins for Minecraft servers cores such as a Paper to create this library!

What is addon for?

Speed or convenience? I choose both!

Addon is a runtime extension of your project. You can write update for your application and don't care about downtime (it will not be there!).

Or you can use addons just for creating extensible projects. For example, telegram bots, you can add some functionality with no need to edit the main code of the bot. Connect the addon!

Dependencies?

Where is aiogram gone?

This library has a built-in tool for managing addon's dependencies. So you don't even need to use command-line to install it using AddonSystem.

Let's try?

LET'S GOO!

Prerequisites

Install addon-system

pip install addon-system

Create addons storage directory, it can have any name and be anywhere inside your project workdir(of course!)

Example:

┌─ KuyuGenesis -- Workdir
└──┌─ addons -- here you go
   ├─ src
   ├─ main.py
   ├─ config.py
   └─ KuyuGenesis.conf

Create your first addon

There are two ways to achieve it

Using library-provided addon creation command line tool:

make-addon -name "SomeAddon" -a "KuyuGama,KugaYumo" -i "KuguYama/SomeAddon" -m __init__ addons

Manually(meh) create addon dir and metafile:

┌─ SomeAddon -- AddonDir (CamelCase)
└──┌─ addon.json -- metafile
   └─ __init__.py -- module set in metafile(can be any python file)

So you now have this project structure:

┌─ KuyuGenesis -- Workdir
└──┌─ addons 
   ├──┌─ SomeAddon -- Addon's directory
   │  └─┌─ addon.json -- metafile
   │    └─ __init__.py -- module set in metafile
   ├─ src
   ├─ main.py
   ├─ config.py
   └─ KuyuGenesis.conf

Initialize the system

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

Here we created instance of the AddonSystem with early created addons root directory and pip library manager. If you use another library manging tool - write your own implementation of library manager that uses it (only three methods!).

Querying addons

Search of addons? YES!

For your needs, you can search for the addons(not on the internet! Yet?)

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

for addon in system.query_addons(name="some", case_insensitivity=True):
    print(addon)

Here we queried for addon by its name case-insensitive. You can query addons by other fields also. Here are all query parameters:

author — author name
name — addon name
description — description
enabled — addon status(about this later)
case_insensitivity — case-insensitive querying

Getting a specific addon

As I wrote above:

Addon's must have unique id

So, if you want to get some exact addon - use its id!

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")
print(addon)

Addon details

What is the use of this addon?

You can get all supported values from metafile using AddonMeta that is always present in addon as "metadata" attribute:

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")
metadata = addon.metadata
print(metadata.id)
print(metadata.name)
print(metadata.description)
print(metadata.version)
print(metadata.depends)
print(metadata.authors)
print(metadata.module)

Addon metafile has one more field "extra." Which can be used to store custom values:

from typing import Any
from pathlib import Path

from addon_system import AddonSystem, AddonMetaExtra
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")


class Extra(AddonMetaExtra):
    __defaults__ = {"handles_events": []}
    handles_events: list[str]
    priority: int

    def validate(self, data: dict[str, Any]) -> bool:
        handles_events = data.get("handles_events")
        if not isinstance(handles_events, list):
            return False
        
        # If not all elements are str -> return False
        if isinstance(handles_events, list) and (
            len(handles_events) != 0
            and all(map(lambda e: isinstance(e, str), handles_events))
        ):
            return False

        return True


extra = addon.metadata.extra(Extra)

if "event" in extra.handles_events:
    print(f"{addon.metadata.id} can handle event \"event\"")
    # Set priority extra value and save metafile
    extra.priority = 0
    extra.save()

Note: you can read/edit addon extra info without the need to create your own AddonMetaExtra class subclass. But it is useful when you have to define types of field or validate data from extra info

Dependencies!

To manage dependencies, you have to use the simple interface:

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")

print(addon.metadata.depends)
print("Is dependencies satisfied?", system.check_dependencies(addon))
if not system.check_dependencies(addon):
    system.satisfy_dependencies(addon)
    print("Auto-installed dependencies")
...

Here we checked dependencies of addon and installed it if necessarily

check_dependencies and satisfy_dependencies also can take addon id to manage

Thanks to caching we can call check_dependencies twice without losing much time

Addon status

Another useful (or useless, according to your purposes) think!

Addon status allows the code to know whether to load addon into your project

Usage:

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")

if not system.get_addon_enabled(addon):
    system.enable_addon("KuyuGama/SomeAddon")
else:
    system.disable_addon("KuyuGama/SomeAddon")

for addon in system.query_addons(enabled=True):
    print("Enabled addon:", addon)

To remove confusion:

get_addon_enabled, enable_addon and disable_addon all can take id or instance of addon

Importing addon

Much more interesting, isn't it?

You can import or reload module of addon where and when you want:

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")

module = addon.module()

# Example module interface
event_handlers = {}

module.unpack_handlers(event_handlers)

Note, addon can't be imported without satisfied dependencies. If dependencies are not satisfied, exception will be raised

Interface of addon module is your own designed interface for your purposes.

Because the module is a regular python module, you can
create whatever you want

Reload of module is achieved by using the same function with reload=True argument:

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")

module = addon.module(reload=True)

Value injection

NOTE! That is not safe in case of usage threading! Because it replaces builtins (Only for import time)

Why builtins? Because it will work as it is (without any function calls in addon's module)

Note: In future - builtins will no longer be used for this, so i recommend to use addon_system.utils.resolve_runtime

You can inject values on module initiation, and use it after (will work only for module that set into metafile)

Injection example:

from pathlib import Path

from addon_system import AddonSystem
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")

# "this" name will contain addon instance in addon's module
addon.namespace.update(dict(this=addon))

module = addon.module()

It creates problem - IDEs doesn't know that I injected the name "this".

Let's solve this!

from addon_system import resolve_runtime, Addon

this = resolve_runtime(Addon)

print("Addon module received \"this\" variable with value:", this)

Note:

resolve_runtime also checks requested type with a provided value type and will raise TypeError if it is different

resolve_runtime automatically resolves the name of required variable, but you can also pass it manually, by parameter name

Module Interface

Wait, what? My IDE now suggests to me methods that I could call!

How this works: you create class-representation of the module - library instantiates it with addon and allows you to use it anywhere.

Simple example:

from pathlib import Path
from typing import Any

from addon_system import AddonSystem, ModuleInterface
from addon_system.libraries.pip_manager import PipLibManager


class MyInterface(ModuleInterface):
    def get_supported_events(self) -> list[str]:
        """Returns supported events by this addon"""
        return self.get_func("get_supported_events")()

    def propagate_event(self, event_name: str,
                        event_data: dict[str, Any]) -> bool:
        """Propagates event to this addon, and return True if handled"""
        handler = self.get_func("on_" + event_name)

        if handler is None:
            return False

        return handler(event_data)


root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")

# Value injection can be achieved by using addon.namespace dictionary
addon.namespace.update(dict(this=addon))

interface = addon.interface(
    MyInterface,
    "supported on_load positional argument",
    kwd="supported on_load keyword argument",
)

if "smth" in interface.get_supported_events():
    interface.propagate_event("smth", dict(issued_by="User"))

ModuleInterface class has built-in methods to manipulate on addon's module:

get_func(name: str) — returns function with the given name, if it is not a function — returns None

get_attr(name: str[, default=Any]) — get attribute by the given name, if default is not set - raises AttributeError

set_attrs(**names) — set passed keyword arguments as module attributes

Module unloading

Free my memory, please

Library can try to unload addon's modules

Note: It works better in a pair of ModuleInterface

from pathlib import Path

from addon_system import AddonSystem, ModuleInterface
from addon_system.libraries.pip_manager import PipLibManager

root = Path() / "addons"
system = AddonSystem(root, PipLibManager())

addon = system.get_addon_by_id("KuyuGama/SomeAddon")

module = addon.module()

# To unload module => we must remove all references to it
# (and then python's garbage collector will release used memory by it)
del module
addon.unload_module()

# In case of usage ModuleInterface, it will try to unload 
# all used modules by this addon(addon's module must return 
# a list of the modules in on_load method)
interface = addon.interface(ModuleInterface)

# Will try to unload all used modules by its addon
interface.unload("Argument passed to on_unload module method")
## Or
# addon.unload_interface("Argument passed to on_unload module method")
## if you don't have access to interface instance

NOTE!!! Unload may not work in case if module is used anywhere else. If you use interface - use it instance instead of the addon's module

Also: to unload used modules by this addon => you need to return a list of these modules from on_load module method (it will be called automatically by ModuleInterface class)

I recommend not using addon's module object, instead use ModuleInterface. That is a good idea, because it will unload module if necessary

Addon creation tool

It is easy to create addon!

Library provides tools to create addons via terminal and code:

Command-line addon building

make-addon is designed to create addons easily using terminal

Parameters:
-n / --name — Addon name(must be CamelCase because tool creates addon directory with the same name)
-a / --authors — Comma separated author names
-i / --id — Addon id (If not provided will be created using first author name + "/" + addon name)
-m / --module — Set the main module name of this addon (Useful when creating from source code)
-p / --package — Path to package that will be used as addon source
-v / --version — Version of addon (Usually SemVer)
-d / --description — Description of addon
-D / --depends — Comma separated addon dependencies (in pip freeze format)
-t / --template — Path to module template file (Will be used if no source package is provided)
-f / --force — Force create addon (rewrites addon if exists)
-b / --bake — Build "baked" addon using pybaked library. I Recommend use it in pair with --package parameter
place_to — Directory where addon will be created

In-code addon building

addon_system.addon.builder.AddonBuilder and addon_system.addon.builder.AddonPackageBuilder are designed to build addons from code easily

`addon_system.addon.builder.AddonBuilder`

Methods:

meta(name: str, authors: list[str], version: str, depends: list[str], id: str, description: str)
Sets the metadata of this addon
package(package: AddonPackageBuilder)
Sets the package of this addon
build(path: str | Path | AddonSystem, addon_dir_name: str = None)
Builds addon at given path. If the path is AddonSystem object then addon_dir_name must be passed (addon's root)

`addon_system.addon.builder.AddonPackageBuilder`