Creating cogs for V3

This guide serves as a tutorial on creating cogs for Red V3. It will cover the basics of setting up a package for your cog and the basics of setting up the file structure. We will also point you towards some further resources that may assist you in the process.

Getting started

To start off, be sure that you have installed Python 3.7. Next, you need to decide if you want to develop against the Stable or Develop version of Red. Depending on what your goal is should help determine which version you need.

Attention

The Develop version may have changes on it which break compatibility with the Stable version and other cogs. If your goal is to support both versions, make sure you build compatibility layers or use separate branches to keep compatibility until the next Red release

Open a terminal or command prompt and type one of the following

Stable Version: python3.7 -m pip install -U Red-DiscordBot

Develop Version: python3.7 -m pip install -U git+https://github.com/Cog-Creators/Red-DiscordBot@V3/develop#egg=Red-DiscordBot

(Windows users may need to use py -3.7 or python instead of python3.7)

Setting up a package

To set up a package, we would just need to create a new folder. This should be named whatever you want the cog to be named (for the purposes of this example, we’ll call this mycog). In this folder, create three files: __init__.py, mycog.py, and info.json. Open the folder in a text editor or IDE (examples include Sublime Text 3, Visual Studio Code, Atom, and PyCharm).

Attention

While you can intentionally override Red’s cogs/extensions, this may break things. We would prefer if people wanted custom behavior for any core cog/extension, an issue and/or PR is made Overriding Permissions specifically is dangerous.

Subclassing to make changes to Red’s cogs/extensions may not be a safe way to stay up to date either, as changes to cogs and their interactions with red are not guaranteed to not be breaking.

Any cogs doing this are doing so at their own risk, and should also inform users of associated risks.

Creating a cog

With your package opened in a text editor or IDE, open mycog.py. In that file, place the following code:

from redbot.core import commands

class Mycog(commands.Cog):
    """My custom cog"""

    @commands.command()
    async def mycom(self, ctx):
        """This does stuff!"""
        # Your code will go here
        await ctx.send("I can do stuff!")

Open __init__.py. In that file, place the following:

from .mycog import Mycog

def setup(bot):
    bot.add_cog(Mycog())

Make sure that both files are saved.

Testing your cog

To test your cog, you will need a running instance of V3. Assuming you installed V3 as outlined above, run redbot-setup and provide the requested information. Once that’s done, run Red by doing redbot <instance name> --dev to start Red. Complete the initial setup by providing a valid token and setting a prefix. Once the bot has started up, use the link provided in the console to add it to a server (note that you must have the Manage Server (or Administrator) permission to add bots to a server). Once it’s been added to a server, find the full path to the directory where your cog package is located. In Discord, do [p]addpath <path_to_folder_containing_package>, then do [p]load mycog. Once the cog is loaded, do [p]mycom The bot should respond with I can do stuff!. If it did, you have successfully created a cog!

Note

Package/Folder layout

You must make sure you structure your local path correctly or you get an error about missing the setup function. As cogs are considered packages, they are each contained within separate folders. The folder you need to add using [p]addpath is the parent folder of these package folders. Below is an example

- D:\
-- red-env
-- red-data
-- red-cogs
---- mycog
------ __init__.py
------ mycog.py
---- coolcog
------ __init__.py
------ coolcog.py

You would then use [p]addpath D:\red-cogs to add the path and then you can use [p]load mycog or [p]load coolcog to load them

You can also take a look at our cookiecutter, for help creating the right structure.

Additional resources

Be sure to check out the Migrating Cogs to V3 for some resources on developing cogs for V3. This will also cover differences between V2 and V3 for those who developed cogs for V2.