feat: Add EvalCog for evaluating Python code snippets with error handling

cogs/eval_cog.py

@@ -0,0 +1,61 @@
+import discord
+from discord.ext import commands
+import io
+import textwrap
+import traceback
+
+class EvalCog(commands.Cog):
+    def __init__(self, bot):
+        self.bot = bot
+
+    def cleanup_code(self, content):
+        """Automatically removes code blocks from the code."""
+        # remove ```py\n```
+        if content.startswith('```') and content.endswith('```'):
+            return '\n'.join(content.split('\n')[1:-1])
+        return content.strip('` \n')
+
+    @commands.command(name='evalpy', hidden=True)
+    @commands.is_owner()
+    async def _eval(self, ctx, *, body: str):
+        """Evaluates a code snippet."""
+        env = {
+            'bot': self.bot,
+            'ctx': ctx,
+            'channel': ctx.channel,
+            'author': ctx.author,
+            'guild': ctx.guild,
+            'message': ctx.message,
+            'discord': discord,
+            'commands': commands
+        }
+
+        env.update(globals())
+
+        body = self.cleanup_code(body)
+        stdout = io.StringIO()
+        
+        to_compile = f'async def func():\n{textwrap.indent(body, "  ")}'
+
+        try:
+            exec(to_compile, env)
+        except Exception as e:
+            return await ctx.send(f'```py\n{e.__class__.__name__}: {e}\n```')
+
+        func = env['func']
+        try:
+            with io.redirect_stdout(stdout):
+                ret = await func()
+        except Exception as e:
+            value = stdout.getvalue()
+            await ctx.send(f'```py\n{value}{traceback.format_exc()}\n```')
+        else:
+            value = stdout.getvalue()
+            if ret is None:
+                if value:
+                    await ctx.send(f'```py\n{value}\n```')
+            else:
+                await ctx.send(f'```py\n{value}{ret}\n```')
+
+async def setup(bot):
+    await bot.add_cog(EvalCog(bot))