Flag Parsing

A util for discord.py bots that allow passing flags into commands.

To install, run the following command:

pip install discord-flags

Basic example usage:

import discord
from discord.ext import flags, commands

bot = commands.Bot("!")

# Invocation: !flags --count=5 --string=hello world --user=Xua --thing

@bot.command(cls=flags.FlagCommand)
async def flags(ctx, *, flag: flags.FlagParser(
    count=int,
    string=str,
    user=discord.User,
    thing=bool
) = flags.EmptyFlags):
    c = flag['count']
    s = flag['string']
    u = flag['user']
    t = flag['thing']
    # Ignore any error about EmptyFlags not implementing __getitem__
    
    await ctx.send(f"--count: {type(c).__name__} {c}\n"
                   f"--string: {type(s).__name__} {s}\n"
                   f"--user: {type(u).__name__} {u}\n"
                   f"--thing: {type(t).__name__}: {t}")
    # Will output:
    # --count: int 5
    # --string: str hello world
    # --user: User Xua#4427       
    # --thing: True

Quick docs:

flags.EmptyFlags

This will return a dict which every key will always return None. This is for when no flags are specified. If flags are specified, any omitted flags will default to None.

flags.FlagParser

The converter for the flags. You must pass an instance as a type hint, and it must have at least 1 valid flag.

They must be passed as name=type.

user=discord.User will attempted to convert --user=Xua into a user object. This will raise an error if it fails.

flags.FlagCommand

If you wish to use flags.FlagParser, your command must be a subclass of this command. This is to ensure that the default arguments are properly converted.

Credit to khazhyk for this idea.

flags.ParamDefault

Again, if your command is a subclass of flags.FlagCommand, you can use custom Default arguments with your command.

Example usage here shows the argument user defaulting to the command author, without the use of user = None; user = user or ctx.author

from discord.ext import flags
import discord


class Author(flags.ParamDefault):
    async def default(self, ctx):
        return ctx.author


@bot.command(cls=flags.FlagCommand)
async def me(ctx, user: discord.User = Author):
    await ctx.send(user.mention)
    # will mention you if you do not supply an argument.

Credits:

khazhyk for creating the original pull request for the default function (link)

Rapptz for creating the discord.py library.