discordpy-argparse.py

from argparse import Namespace, ArgumentParser as AP
import contextlib
import io

from discord.ext.commands import Converter


class ArgumentException(BaseException):
    pass


class Default(Namespace):
    def __repr__(self):
        return f"'{' '.join(f'--{k}={v}'for k, v in self._get_kwargs())}'"


class Argument:
    """ Class to hold arguments to be passed to add_argument """
    def __init__(self, *args, **kwargs):
        self.args = args
        self.kwargs = kwargs

    def register(self, parser):
        parser.add_argument(*self.args, **self.kwargs)


class ArgumentParser(AP):
    """ Custom parser class to redirect errors to the current channel """
    def __init__(self, *args, **kwargs):
        super().__init__(*args, add_help=False, **kwargs)

    def error(self, exc):
        coro = self.ctx.send(f"Error: `{exc}`")
        self.ctx.bot.loop.create_task(coro)
        raise ArgumentException("Invalid arguments")

    def set_ctx(self, ctx):
        self.ctx = ctx


class ArgParseConverter(Converter):
    """ Custom command class for argparse """
    def __init__(self, arguments, *args, **kwargs):
        self.arguments = arguments
        # Create the parser
        self.parser = ArgumentParser(*args, **kwargs)

        # Register all arguments
        for argument in arguments:
            argument.register(self.parser)
        self.do_help = True

    async def convert(self, ctx, arg):
        sio = io.StringIO()
        with contextlib.redirect_stdout(sio):
            self.parser.print_help()
        sio.seek(0)
        ctx.command.usage = sio.read()[7:]

        self.parser.set_ctx(ctx)
        return self.parser.parse_args(arg.split())
      
# Example command:
@commands.command(aliases=["words", "wc"])
async def wordcloud(self, ctx, *, args: ArgParseConverter(
        [Argument("--mask", help="Mask to use", default="mask"),
         Argument("--font", help="Font to use", default="random"),
         Argument("--color", help="Background color"),
         Argument(
             "--count", default=1000, type=int,
             help="Number of messages to use")])=Default(
                 count=1000,
                 font="random")):