feat: Move additional event handler functionality to Client

[davidhozic]

Summary

The pull request introduces changes proposed in #1906 .

It allows the user to register multiple on_ event handlers inside the Client objects instead of just inBot.

import discord
import secret


class MyClient(discord.Client):
    async def on_ready(self):
        print("Default handler")


intents = discord.Intents.default()
intents.message_content = True
client = MyClient(intents=intents)


@client.event # Override the default handler
async def on_ready():
    print(f"Handler 1: {client.user.name} has logged in!")

@client.listen # Additional handler
async def on_ready():
    print(f"Handler 2: {client.user.name} has logged in!")

@client.listen("on_ready") # Additional handler
async def ready_handler():
    print(f"Handler 3: {client.user.name} has logged in!")

@client.listen("on_ready") # Additional handler
async def ready_handler():
    print(f"Handler 4: {client.user.name} has logged in!")

@client.listen()
async def on_message(message: discord.Message):
    print(f"Received message {message.content}")


@client.listen("on_guild_channel_update")
async def channel_updated(prev: discord.ChannelType, curr:discord.ChannelType):
    print(prev.name, curr.name)

client.run(secret.TOKEN)

Also add support to allow @listen without () at the end.

import discord
import secret

bot = discord.Bot()

@bot.listen()
async def on_ready():
    print(f"Handler 1: {bot.user.name} has logged in!")

@bot.listen # <-------- No ()
async def on_ready():
    print(f"Handler 2: {bot.user.name} has logged in!")

bot.run(secret.TOKEN)

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting,
  examples, ...).

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.

[codecov]

Codecov Report

Merging #1907 (e1e8dc6) into master (8c95c94) will decrease coverage by 0.02%.
The diff coverage is 9.67%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1907      +/-   ##
==========================================
- Coverage   33.37%   33.36%   -0.02%     
==========================================
  Files          97       97              
  Lines       18847    18851       +4     
==========================================
- Hits         6290     6289       -1     
- Misses      12557    12562       +5     

Flag	Coverage Δ
macos-latest-3.10	33.34% <9.67%> (-0.02%)	⬇️
macos-latest-3.11	33.34% <9.67%> (-0.02%)	⬇️
macos-latest-3.8	33.35% <9.67%> (-0.02%)	⬇️
macos-latest-3.9	33.35% <9.67%> (-0.02%)	⬇️
ubuntu-latest-3.10	33.34% <9.67%> (-0.02%)	⬇️
ubuntu-latest-3.11	33.34% <9.67%> (-0.02%)	⬇️
ubuntu-latest-3.8	33.35% <9.67%> (-0.02%)	⬇️
ubuntu-latest-3.9	33.35% <9.67%> (-0.02%)	⬇️
windows-latest-3.10	33.34% <9.67%> (-0.02%)	⬇️
windows-latest-3.11	33.34% <9.67%> (-0.02%)	⬇️
windows-latest-3.8	33.35% <9.67%> (-0.02%)	⬇️
windows-latest-3.9	33.35% <9.67%> (-0.02%)	⬇️

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Impacted Files	Coverage Δ
discord/bot.py	18.53% <ø> (+0.21%)	⬆️
discord/client.py	27.73% <9.67%> (-1.21%)	⬇️

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Done