A good eval for discord.py

eval.py

import ast
import discord

from discord.ext import commands


def insert_returns(body):
    # insert return stmt if the last expression is a expression statement
    if isinstance(body[-1], ast.Expr):
        body[-1] = ast.Return(body[-1].value)
        ast.fix_missing_locations(body[-1])

    # for if statements, we insert returns into the body and the orelse
    if isinstance(body[-1], ast.If):
        insert_returns(body[-1].body)
        insert_returns(body[-1].orelse)

    # for with blocks, again we insert returns into the body
    if isinstance(body[-1], ast.With):
        insert_returns(body[-1].body)


@commands.command()
async def eval_fn(ctx, *, cmd):
    """Evaluates input.

    Input is interpreted as newline seperated statements.
    If the last statement is an expression, that is the return value.

    Usable globals:
      - `bot`: the bot instance
      - `discord`: the discord module
      - `commands`: the discord.ext.commands module
      - `ctx`: the invokation context
      - `__import__`: the builtin `__import__` function

    Such that `>eval 1 + 1` gives `2` as the result.

    The following invokation will cause the bot to send the text '9'
    to the channel of invokation and return '3' as the result of evaluating

    >eval ```
    a = 1 + 2
    b = a * 2
    await ctx.send(a + b)
    a
    ```
    """
    fn_name = "_eval_expr"

    cmd = cmd.strip("` ")

    # add a layer of indentation
    cmd = "\n".join(f"    {i}" for i in cmd.splitlines())

    # wrap in async def body
    body = f"async def {fn_name}():\n{cmd}"

    parsed = ast.parse(body)
    body = parsed.body[0].body

    insert_returns(body)

    env = {
        'bot': ctx.bot,
        'discord': discord,
        'commands': commands,
        'ctx': ctx,
        '__import__': __import__
    }
    exec(compile(parsed, filename="<ast>", mode="exec"), env)

    result = (await eval(f"{fn_name}()", env))
    await ctx.send(result)

Please do not use this! This is not safe and people can execute dangerous code with this function.

It's only as dangerous as you make it. If you add appropriate checks to ensure limited people have access to this command, there is no issue.

Please do not use this! This is not safe and people can execute dangerous code with this function.

@commands.is_owner

Great overall, I'd suggest also stripping code block syntax labels e.g. ```py

It says "TypeError: arguement type "bot" is not iterable".

What is this code supposed to do?

it says insert_returns is not defined

it says insert_returns is not defined

you need to copy the whole thing not just the eval function