discord.py@rewrite tool to monkey patch functions that run before every invocation of Messageble.send

.gitignore

*.swp
*.py[cod]
venv/
.venv/

example.py

#!/usr/bin/env python3
# encoding: utf-8

import discord
from discord.ext import commands

import io

from patch import global_message_send_hook


bot = commands.Bot(command_prefix=commands.when_mentioned)

@global_message_send_hook
async def attach_if_too_long(original_send, message=None, *args, **kwargs):
	if message is None: return True,

	message = str(message)

	if len(message) > 2000:
		file = discord.File(fp=io.StringIO(message), filename='message.txt')
		message = await original_send('Way too long. Message attached.', *args, **kwargs, file=file)
		return False, message

	return True,

@bot.command()
async def send_big_message(context):
	print((await context.send('aA'*1001)).id)

@bot.event
async def on_ready():
	print('Ready.')


if __name__ == '__main__':
	import os

	bot.run(os.environ['discord_bot_token'])

patch.py

#!/usr/bin/env python3
# encoding: utf-8

import functools

import discord.abc

_hooks = []
_patched = False
_old_send = discord.abc.Messageable.send

def global_message_send_hook(func):
	_hooks.append(func)
	_monkey_patch()
	# allow this to be used as a decorator
	return func

unregister = _hooks.remove

def restore():
	discord.abc.Messageable.send = _old_send

def _monkey_patch():
	global _patched

	if _patched:
		return

	@functools.wraps(_old_send)
	async def send(self, *args, **kwargs):
		# old_send is not a bound method.
		# "bind" it to self, so that the user doesnt have to pass in self manually
		bound_old_send = functools.partial(_old_send, self)

		for hook in _hooks:
			# allow the user to prevent default send behavior
			# by returning False
			# pass in old_send so that the user can still send
			# using the original behavior
			should_continue, *result = await hook(bound_old_send, *args, **kwargs)
			if not should_continue:
				return result[0]

		return await _old_send(self, *args, **kwargs)

	discord.abc.Messageable.send = send
	_patched = True