Cogs¶

Cogs are an important part of Nextcord which allow you to organise your events and commands into different files. They represent a fairly drastic change in how you write your events, commands, and bots, so it's useful to do them early on before you have too much logic in your main file.

Note

Cogs require a basic understanding of OOP/classes in Python. If you're not familiar with this, check out the first video in Corey Schafer's OOP Tutorial.

Now that we're using cogs we're going to abandon most of the code we have from previous parts, since it needs to change significantly to be used with cogs, and some of the functionality we've implemented so far isn't very useful anyway.

Note

In this part I'll refer to cogs and extensions, and the difference between both is important. A cog is a single class that inherits from Cog, which encapsulates commands and events. An extension is a collection of cogs which has a setup function and can be loaded via the bot's load_extension method, although you will often find extensions with just one cog.

In the previous parts with Nextcord we used the Client class since this supports slash commands natively, but as of right now the regular client does not support using Cogs, and as a result we will have to switch to using nextcord.ext.commands.Bot, which is essentially the same as nextcord.Client but supports loading extensions and cogs. Let's create a file named main.py and add in the base code:

main.py

from nextcord.ext.commands import Bot

bot = Bot()

bot.run("YOUR_BOT_TOKEN")

Now, we need to create a file that we'll put our cog in, let's call it ping.py as we'll be putting a basic ping command in here:

ping.py

from nextcord import Interaction, slash_command
from nextcord.ext.commands import Bot, Cog


class Ping(Cog):
    def __init__(self, bot: Bot) -> None:
        self.bot = bot

    @slash_command(name="ping", description="A simple ping command.", guild_ids=[...])
    async def ping(self, inter: Interaction) -> None:
        await inter.send(f"Pong! {self.bot.latency * 1000:.2f}ms")

As you can probably see, a lot of this is similar to the ping command we made in part 4 of the beginner section. There are a couple of important parts to explain which are different:

We're now using the slash_command decorator . We can no longer use the bot object to make decorators since we don't have the bot object as it's in another file.
Everything is now in a class. This is a fundamental part of cogs, all of their functionality is encapsulated within a class.

In this section of code:

class Ping(Cog):
    def __init__(self, bot: Bot) -> None:
        self.bot = bot

What we're doing is defining a new cog, and letting it take a bot object in its constructor. We're doing this so that we can then access that bot object for the ping command so we can retrieve the bot's websocket latency.

We still have a final piece of code we need to add to the cog's file in order for the cog to be registered, a setup function:

ping.py

# This goes at the bottom of the file.

def setup(bot: Bot) -> None:
    bot.add_cog(Ping(bot))

This function is what nextcord looks for when loading an extension, and the function signature will always be setup(self, bot: Bot) -> None.

Finally, we need to load the cog in our main file:

main.py

from nextcord.ext.commands import Bot

bot = Bot()

bot.load_extension("ping")

bot.run("YOUR_BOT_TOKEN")

Note that when loading an extension we omit the .py extension. Extensions are loaded via Python imports behind the scenes, so we reference them in the same way we would write an import. If you have an extension in ./cogs/ping.py you would load it with bot.load_extension("cogs.ping").