添加Cog时触发AttributeError：'Misc'对象无'bot'属性

在开发Discord机器人时，Misc.py这个Cog触发了AttributeError，错误提示'Misc' object has no attribute 'bot'，以下是相关代码和错误信息：

主Discord机器人文件代码 #

import discord
from discord.ext import commands
import random
import json
import os
import asyncio

def get_prefix(bot, message):
    with open("jsonfiles/prefixes.json", "r") as f:
        prefixes = json.load(f)
        
    return prefixes[str(message.guild.id)]
            
bot = commands.Bot(command_prefix=get_prefix, intents=discord.Intents.all())

with open("textfiles/keys.txt", "r") as f:
    lines = f.readlines()
    bot_token = lines[0]
    bot_invite_url = lines[1]

@bot.event
async def on_ready():
    print("Successfully connected to Discord.")
    print("To invite, copy and paste this link into url and go from there. ", bot_invite_url)
    
@bot.event
async def on_guild_join(guild):
    with open("jsonfiles/prefixes.json", "r") as f:
        prefixes = json.load(f)
        
    prefixes[str(guild.id)] = "="
    
    with open("jsonfiles/prefixes.json", "w") as f:
        json.dump(prefixes, f, indent=4)

@bot.event
async def on_guild_remove(guild):
    with open("jsonfiles/prefixes.json", "r") as f:
        prefixes = json.load(f)
        
    prefixes.pop(str(guild.id))
    
    with open("jsonfiles/prefixes.json", "w") as f:
        json.dump(prefixes, f, indent=4) 
        
async def load():
    for filename in os.listdir("./cogs"):
        if filename.endswith(".py"):
            await bot.load_extension(f"cogs.{filename[:-3]}")   

    
async def main():
    async with bot:
        await load()
        await bot.start(bot_token)

asyncio.run(main())

出现问题的Cog代码（Misc.py） #

import discord
from discord.ext import commands
import random

class Misc(commands.Cog):
    def __init__(self, bot):
        bot = self.bot
        
    @commands.Cog.listener()
    async def on_ready(self):
        print("Misc.py is online.")
        
    @commands.command(aliases=["8ball", "eightball"])
    async def magic_eight_ball(self, ctx, *, question):
        with open("textfiles/responses.txt", "r") as f:
            random_responses = f.readlines()
            
        response = random.choice(random_responses)
        
        await ctx.send(response)
        
#the error occurs here (i at least think)
async def setup(bot):
    await bot.add_cog(Misc(bot))

触发的错误信息 #

File "d:\DiscordBot\cogs\misc.py", line 7, in __init__
    bot = self.bot
          ^^^^^^^^
AttributeError: 'Misc' object has no attribute 'bot'

问题原因与解决方案 #

这是代码疏漏，不是bug。问题出在Misc类的__init__方法里，赋值语句写反了：

• 错误写法：bot = self.bot，试图将未定义的self.bot赋值给局部变量bot，但此时self.bot还不存在，直接触发AttributeError。
• 正确写法：将传入的bot实例绑定到类的属性上，即：

def __init__(self, bot):
    self.bot = bot

修改后，Cog就能正确接收并持有机器人实例，错误即可解决。

内容的提问来源于stack exchange，提问作者Paradoxial