Source code for discord.ext.commands.core

# -*- coding: utf-8 -*-

"""
The MIT License (MIT)

Copyright (c) 2015-present Rapptz

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
"""

import asyncio
import functools
import inspect
import typing
import datetime

import discord

from .errors import *
from .cooldowns import Cooldown, BucketType, CooldownMapping, MaxConcurrency
from . import converter as converters
from ._types import _BaseCommand
from .cog import Cog

__all__ = (
    'Command',
    'Group',
    'GroupMixin',
    'command',
    'group',
    'has_role',
    'has_permissions',
    'has_any_role',
    'check',
    'check_any',
    'before_invoke',
    'after_invoke',
    'bot_has_role',
    'bot_has_permissions',
    'bot_has_any_role',
    'cooldown',
    'max_concurrency',
    'dm_only',
    'guild_only',
    'is_owner',
    'is_nsfw',
    'has_guild_permissions',
    'bot_has_guild_permissions'
)

def wrap_callback(coro):
    @functools.wraps(coro)
    async def wrapped(*args, **kwargs):
        try:
            ret = await coro(*args, **kwargs)
        except CommandError:
            raise
        except asyncio.CancelledError:
            return
        except Exception as exc:
            raise CommandInvokeError(exc) from exc
        return ret
    return wrapped

def hooked_wrapped_callback(command, ctx, coro):
    @functools.wraps(coro)
    async def wrapped(*args, **kwargs):
        try:
            ret = await coro(*args, **kwargs)
        except CommandError:
            ctx.command_failed = True
            raise
        except asyncio.CancelledError:
            ctx.command_failed = True
            return
        except Exception as exc:
            ctx.command_failed = True
            raise CommandInvokeError(exc) from exc
        finally:
            if command._max_concurrency is not None:
                await command._max_concurrency.release(ctx)

            await command.call_after_hooks(ctx)
        return ret
    return wrapped

def _convert_to_bool(argument):
    lowered = argument.lower()
    if lowered in ('yes', 'y', 'true', 't', '1', 'enable', 'on'):
        return True
    elif lowered in ('no', 'n', 'false', 'f', '0', 'disable', 'off'):
        return False
    else:
        raise BadBoolArgument(lowered)

class _CaseInsensitiveDict(dict):
    def __contains__(self, k):
        return super().__contains__(k.casefold())

    def __delitem__(self, k):
        return super().__delitem__(k.casefold())

    def __getitem__(self, k):
        return super().__getitem__(k.casefold())

    def get(self, k, default=None):
        return super().get(k.casefold(), default)

    def pop(self, k, default=None):
        return super().pop(k.casefold(), default)

    def __setitem__(self, k, v):
        super().__setitem__(k.casefold(), v)

class Command(_BaseCommand):
    r"""A class that implements the protocol for a bot text command.

    These are not created manually, instead they are created via the
    decorator or functional interface.

    Attributes
    -----------
    name: :class:`str`
        The name of the command.
    callback: :ref:`coroutine <coroutine>`
        The coroutine that is executed when the command is called.
    help: :class:`str`
        The long help text for the command.
    brief: Optional[:class:`str`]
        The short help text for the command.
    usage: Optional[:class:`str`]
        A replacement for arguments in the default help text.
    aliases: Union[List[:class:`str`], Tuple[:class:`str`]]
        The list of aliases the command can be invoked under.
    enabled: :class:`bool`
        A boolean that indicates if the command is currently enabled.
        If the command is invoked while it is disabled, then
        :exc:`.DisabledCommand` is raised to the :func:`.on_command_error`
        event. Defaults to ``True``.
    parent: Optional[:class:`Command`]
        The parent command that this command belongs to. ``None`` if there
        isn't one.
    cog: Optional[:class:`Cog`]
        The cog that this command belongs to. ``None`` if there isn't one.
    checks: List[Callable[[:class:`.Context`], :class:`bool`]]
        A list of predicates that verifies if the command could be executed
        with the given :class:`.Context` as the sole parameter. If an exception
        is necessary to be thrown to signal failure, then one inherited from
        :exc:`.CommandError` should be used. Note that if the checks fail then
        :exc:`.CheckFailure` exception is raised to the :func:`.on_command_error`
        event.
    description: :class:`str`
        The message prefixed into the default help command.
    hidden: :class:`bool`
        If ``True``\, the default help command does not show this in the
        help output.
    rest_is_raw: :class:`bool`
        If ``False`` and a keyword-only argument is provided then the keyword
        only argument is stripped and handled as if it was a regular argument
        that handles :exc:`.MissingRequiredArgument` and default values in a
        regular matter rather than passing the rest completely raw. If ``True``
        then the keyword-only argument will pass in the rest of the arguments
        in a completely raw matter. Defaults to ``False``.
    invoked_subcommand: Optional[:class:`Command`]
        The subcommand that was invoked, if any.
    require_var_positional: :class:`bool`
        If ``True`` and a variadic positional argument is specified, requires
        the user to specify at least one argument. Defaults to ``False``.

        .. versionadded:: 1.5

    ignore_extra: :class:`bool`
        If ``True``\, ignores extraneous strings passed to a command if all its
        requirements are met (e.g. ``?foo a b c`` when only expecting ``a``
        and ``b``). Otherwise :func:`.on_command_error` and local error handlers
        are called with :exc:`.TooManyArguments`. Defaults to ``True``.
    cooldown_after_parsing: :class:`bool`
        If ``True``\, cooldown processing is done after argument parsing,
        which calls converters. If ``False`` then cooldown processing is done
        first and then the converters are called second. Defaults to ``False``.
    """

    def __new__(cls, *args, **kwargs):
        # if you're wondering why this is done, it's because we need to ensure
        # we have a complete original copy of **kwargs even for classes that
        # mess with it by popping before delegating to the subclass __init__.
        # In order to do this, we need to control the instance creation and
        # inject the original kwargs through __new__ rather than doing it
        # inside __init__.
        self = super().__new__(cls)

        # we do a shallow copy because it's probably the most common use case.
        # this could potentially break if someone modifies a list or something
        # while it's in movement, but for now this is the cheapest and
        # fastest way to do what we want.
        self.__original_kwargs__ = kwargs.copy()
        return self

    def __init__(self, func, **kwargs):
        if not asyncio.iscoroutinefunction(func):
            raise TypeError('Callback must be a coroutine.')

        self.name = name = kwargs.get('name') or func.__name__
        if not isinstance(name, str):
            raise TypeError('Name of a command must be a string.')

        self.callback = func
        self.enabled = kwargs.get('enabled', True)

        help_doc = kwargs.get('help')
        if help_doc is not None:
            help_doc = inspect.cleandoc(help_doc)
        else:
            help_doc = inspect.getdoc(func)
            if isinstance(help_doc, bytes):
                help_doc = help_doc.decode('utf-8')

        self.help = help_doc

        self.brief = kwargs.get('brief')
        self.usage = kwargs.get('usage')
        self.rest_is_raw = kwargs.get('rest_is_raw', False)
        self.aliases = kwargs.get('aliases', [])

        if not isinstance(self.aliases, (list, tuple)):
            raise TypeError("Aliases of a command must be a list or a tuple of strings.")

        self.description = inspect.cleandoc(kwargs.get('description', ''))
        self.hidden = kwargs.get('hidden', False)

        try:
            checks = func.__commands_checks__
            checks.reverse()
        except AttributeError:
            checks = kwargs.get('checks', [])
        finally:
            self.checks = checks

        try:
            cooldown = func.__commands_cooldown__
        except AttributeError:
            cooldown = kwargs.get('cooldown')
        finally:
            self._buckets = CooldownMapping(cooldown)

        try:
            max_concurrency = func.__commands_max_concurrency__
        except AttributeError:
            max_concurrency = kwargs.get('max_concurrency')
        finally:
            self._max_concurrency = max_concurrency

        self.require_var_positional = kwargs.get('require_var_positional', False)
        self.ignore_extra = kwargs.get('ignore_extra', True)
        self.cooldown_after_parsing = kwargs.get('cooldown_after_parsing', False)
        self.cog = None

        # bandaid for the fact that sometimes parent can be the bot instance
        parent = kwargs.get('parent')
        self.parent = parent if isinstance(parent, _BaseCommand) else None

        try:
            before_invoke = func.__before_invoke__
        except AttributeError:
            self._before_invoke = None
        else:
            self.before_invoke(before_invoke)

        try:
            after_invoke = func.__after_invoke__
        except AttributeError:
            self._after_invoke = None
        else:
            self.after_invoke(after_invoke)

    @property
    def callback(self):
        return self._callback

    @callback.setter
    def callback(self, function):
        self._callback = function
        self.module = function.__module__

        signature = inspect.signature(function)
        self.params = signature.parameters.copy()

        # PEP-563 allows postponing evaluation of annotations with a __future__
        # import. When postponed, Parameter.annotation will be a string and must
        # be replaced with the real value for the converters to work later on
        for key, value in self.params.items():
            if isinstance(value.annotation, str):
                self.params[key] = value = value.replace(annotation=eval(value.annotation, function.__globals__))

            # fail early for when someone passes an unparameterized Greedy type
            if value.annotation is converters.Greedy:
                raise TypeError('Unparameterized Greedy[...] is disallowed in signature.')

[docs] def add_check(self, func): """Adds a check to the command. This is the non-decorator interface to :func:`.check`. .. versionadded:: 1.3 Parameters ----------- func The function that will be used as a check. """ self.checks.append(func)
[docs] def remove_check(self, func): """Removes a check from the command. This function is idempotent and will not raise an exception if the function is not in the command's checks. .. versionadded:: 1.3 Parameters ----------- func The function to remove from the checks. """ try: self.checks.remove(func) except ValueError: pass
[docs] def update(self, **kwargs): """Updates :class:`Command` instance with updated attribute. This works similarly to the :func:`.command` decorator in terms of parameters in that they are passed to the :class:`Command` or subclass constructors, sans the name and callback. """ self.__init__(self.callback, **dict(self.__original_kwargs__, **kwargs))
async def __call__(self, *args, **kwargs): """|coro| Calls the internal callback that the command holds. .. note:: This bypasses all mechanisms -- including checks, converters, invoke hooks, cooldowns, etc. You must take care to pass the proper arguments and types to this function. .. versionadded:: 1.3 """ if self.cog is not None: return await self.callback(self.cog, *args, **kwargs) else: return await self.callback(*args, **kwargs) def _ensure_assignment_on_copy(self, other): other._before_invoke = self._before_invoke other._after_invoke = self._after_invoke if self.checks != other.checks: other.checks = self.checks.copy() if self._buckets.valid and not other._buckets.valid: other._buckets = self._buckets.copy() if self._max_concurrency != other._max_concurrency: other._max_concurrency = self._max_concurrency.copy() try: other.on_error = self.on_error except AttributeError: pass return other
[docs] def copy(self): """Creates a copy of this command. Returns -------- :class:`Command` A new instance of this command. """ ret = self.__class__(self.callback, **self.__original_kwargs__) return self._ensure_assignment_on_copy(ret)
def _update_copy(self, kwargs): if kwargs: kw = kwargs.copy() kw.update(self.__original_kwargs__) copy = self.__class__(self.callback, **kw) return self._ensure_assignment_on_copy(copy) else: return self.copy() async def dispatch_error(self, ctx, error): ctx.command_failed = True cog = self.cog try: coro = self.on_error except AttributeError: pass else: injected = wrap_callback(coro) if cog is not None: await injected(cog, ctx, error) else: await injected(ctx, error) try: if cog is not None: local = Cog._get_overridden_method(cog.cog_command_error) if local is not None: wrapped = wrap_callback(local) await wrapped(ctx, error) finally: ctx.bot.dispatch('command_error', ctx, error) async def _actual_conversion(self, ctx, converter, argument, param): if converter is bool: return _convert_to_bool(argument) try: module = converter.__module__ except AttributeError: pass else: if module is not None and (module.startswith('discord.') and not module.endswith('converter')): converter = getattr(converters, converter.__name__ + 'Converter', converter) try: if inspect.isclass(converter): if issubclass(converter, converters.Converter): instance = converter() ret = await instance.convert(ctx, argument) return ret else: method = getattr(converter, 'convert', None) if method is not None and inspect.ismethod(method): ret = await method(ctx, argument) return ret elif isinstance(converter, converters.Converter): ret = await converter.convert(ctx, argument) return ret except CommandError: raise except Exception as exc: raise ConversionError(converter, exc) from exc try: return converter(argument) except CommandError: raise except Exception as exc: try: name = converter.__name__ except AttributeError: name = converter.__class__.__name__ raise BadArgument('Converting to "{}" failed for parameter "{}".'.format(name, param.name)) from exc async def do_conversion(self, ctx, converter, argument, param): try: origin = converter.__origin__ except AttributeError: pass else: if origin is typing.Union: errors = [] _NoneType = type(None) for conv in converter.__args__: # if we got to this part in the code, then the previous conversions have failed # so we should just undo the view, return the default, and allow parsing to continue # with the other parameters if conv is _NoneType and param.kind != param.VAR_POSITIONAL: ctx.view.undo() return None if param.default is param.empty else param.default try: value = await self._actual_conversion(ctx, conv, argument, param) except CommandError as exc: errors.append(exc) else: return value # if we're here, then we failed all the converters raise BadUnionArgument(param, converter.__args__, errors) return await self._actual_conversion(ctx, converter, argument, param) def _get_converter(self, param): converter = param.annotation if converter is param.empty: if param.default is not param.empty: converter = str if param.default is None else type(param.default) else: converter = str return converter async def transform(self, ctx, param): required = param.default is param.empty converter = self._get_converter(param) consume_rest_is_special = param.kind == param.KEYWORD_ONLY and not self.rest_is_raw view = ctx.view view.skip_ws() # The greedy converter is simple -- it keeps going until it fails in which case, # it undos the view ready for the next parameter to use instead if type(converter) is converters._Greedy: if param.kind == param.POSITIONAL_OR_KEYWORD or param.kind == param.POSITIONAL_ONLY: return await self._transform_greedy_pos(ctx, param, required, converter.converter) elif param.kind == param.VAR_POSITIONAL: return await self._transform_greedy_var_pos(ctx, param, converter.converter) else: # if we're here, then it's a KEYWORD_ONLY param type # since this is mostly useless, we'll helpfully transform Greedy[X] # into just X and do the parsing that way. converter = converter.converter if view.eof: if param.kind == param.VAR_POSITIONAL: raise RuntimeError() # break the loop if required: if self._is_typing_optional(param.annotation): return None raise MissingRequiredArgument(param) return param.default previous = view.index if consume_rest_is_special: argument = view.read_rest().strip() else: argument = view.get_quoted_word() view.previous = previous return await self.do_conversion(ctx, converter, argument, param) async def _transform_greedy_pos(self, ctx, param, required, converter): view = ctx.view result = [] while not view.eof: # for use with a manual undo previous = view.index view.skip_ws() try: argument = view.get_quoted_word() value = await self.do_conversion(ctx, converter, argument, param) except (CommandError, ArgumentParsingError): view.index = previous break else: result.append(value) if not result and not required: return param.default return result async def _transform_greedy_var_pos(self, ctx, param, converter): view = ctx.view previous = view.index try: argument = view.get_quoted_word() value = await self.do_conversion(ctx, converter, argument, param) except (CommandError, ArgumentParsingError): view.index = previous raise RuntimeError() from None # break loop else: return value @property def clean_params(self): """OrderedDict[:class:`str`, :class:`inspect.Parameter`]: Retrieves the parameter OrderedDict without the context or self parameters. Useful for inspecting signature. """ result = self.params.copy() if self.cog is not None: # first parameter is self result.popitem(last=False) try: # first/second parameter is context result.popitem(last=False) except Exception: raise ValueError('Missing context parameter') from None return result @property def full_parent_name(self): """:class:`str`: Retrieves the fully qualified parent command name. This the base command name required to execute it. For example, in ``?one two three`` the parent name would be ``one two``. """ entries = [] command = self while command.parent is not None: command = command.parent entries.append(command.name) return ' '.join(reversed(entries)) @property def parents(self): """List[:class:`Command`]: Retrieves the parents of this command. If the command has no parents then it returns an empty :class:`list`. For example in commands ``?a b c test``, the parents are ``[c, b, a]``. .. versionadded:: 1.1 """ entries = [] command = self while command.parent is not None: command = command.parent entries.append(command) return entries @property def root_parent(self): """Optional[:class:`Command`]: Retrieves the root parent of this command. If the command has no parents then it returns ``None``. For example in commands ``?a b c test``, the root parent is ``a``. """ if not self.parent: return None return self.parents[-1] @property def qualified_name(self): """:class:`str`: Retrieves the fully qualified command name. This is the full parent name with the command name as well. For example, in ``?one two three`` the qualified name would be ``one two three``. """ parent = self.full_parent_name if parent: return parent + ' ' + self.name else: return self.name def __str__(self): return self.qualified_name async def _parse_arguments(self, ctx): ctx.args = [ctx] if self.cog is None else [self.cog, ctx] ctx.kwargs = {} args = ctx.args kwargs = ctx.kwargs view = ctx.view iterator = iter(self.params.items()) if self.cog is not None: # we have 'self' as the first parameter so just advance # the iterator and resume parsing try: next(iterator) except StopIteration: fmt = 'Callback for {0.name} command is missing "self" parameter.' raise discord.ClientException(fmt.format(self)) # next we have the 'ctx' as the next parameter try: next(iterator) except StopIteration: fmt = 'Callback for {0.name} command is missing "ctx" parameter.' raise discord.ClientException(fmt.format(self)) for name, param in iterator: if param.kind == param.POSITIONAL_OR_KEYWORD or param.kind == param.POSITIONAL_ONLY: transformed = await self.transform(ctx, param) args.append(transformed) elif param.kind == param.KEYWORD_ONLY: # kwarg only param denotes "consume rest" semantics if self.rest_is_raw: converter = self._get_converter(param) argument = view.read_rest() kwargs[name] = await self.do_conversion(ctx, converter, argument, param) else: kwargs[name] = await self.transform(ctx, param) break elif param.kind == param.VAR_POSITIONAL: if view.eof and self.require_var_positional: raise MissingRequiredArgument(param) while not view.eof: try: transformed = await self.transform(ctx, param) args.append(transformed) except RuntimeError: break if not self.ignore_extra and not view.eof: raise TooManyArguments('Too many arguments passed to ' + self.qualified_name) async def call_before_hooks(self, ctx): # now that we're done preparing we can call the pre-command hooks # first, call the command local hook: cog = self.cog if self._before_invoke is not None: # should be cog if @commands.before_invoke is used instance = getattr(self._before_invoke, '__self__', cog) # __self__ only exists for methods, not functions # however, if @command.before_invoke is used, it will be a function if instance: await self._before_invoke(instance, ctx) else: await self._before_invoke(ctx) # call the cog local hook if applicable: if cog is not None: hook = Cog._get_overridden_method(cog.cog_before_invoke) if hook is not None: await hook(ctx) # call the bot global hook if necessary hook = ctx.bot._before_invoke if hook is not None: await hook(ctx) async def call_after_hooks(self, ctx): cog = self.cog if self._after_invoke is not None: instance = getattr(self._after_invoke, '__self__', cog) if instance: await self._after_invoke(instance, ctx) else: await self._after_invoke(ctx) # call the cog local hook if applicable: if cog is not None: hook = Cog._get_overridden_method(cog.cog_after_invoke) if hook is not None: await hook(ctx) hook = ctx.bot._after_invoke if hook is not None: await hook(ctx) def _prepare_cooldowns(self, ctx): if self._buckets.valid: dt = ctx.message.edited_at or ctx.message.created_at current = dt.replace(tzinfo=datetime.timezone.utc).timestamp() bucket = self._buckets.get_bucket(ctx.message, current) retry_after = bucket.update_rate_limit(current) if retry_after: raise CommandOnCooldown(bucket, retry_after) async def prepare(self, ctx): ctx.command = self if not await self.can_run(ctx): raise CheckFailure('The check functions for command {0.qualified_name} failed.'.format(self)) if self._max_concurrency is not None: await self._max_concurrency.acquire(ctx) try: if self.cooldown_after_parsing: await self._parse_arguments(ctx) self._prepare_cooldowns(ctx) else: self._prepare_cooldowns(ctx) await self._parse_arguments(ctx) await self.call_before_hooks(ctx) except: if self._max_concurrency is not None: await self._max_concurrency.release(ctx) raise
[docs] def is_on_cooldown(self, ctx): """Checks whether the command is currently on cooldown. Parameters ----------- ctx: :class:`.Context` The invocation context to use when checking the commands cooldown status. Returns -------- :class:`bool` A boolean indicating if the command is on cooldown. """ if not self._buckets.valid: return False bucket = self._buckets.get_bucket(ctx.message) dt = ctx.message.edited_at or ctx.message.created_at current = dt.replace(tzinfo=datetime.timezone.utc).timestamp() return bucket.get_tokens(current) == 0
[docs] def reset_cooldown(self, ctx): """Resets the cooldown on this command. Parameters ----------- ctx: :class:`.Context` The invocation context to reset the cooldown under. """ if self._buckets.valid: bucket = self._buckets.get_bucket(ctx.message) bucket.reset()
[docs] def get_cooldown_retry_after(self, ctx): """Retrieves the amount of seconds before this command can be tried again. .. versionadded:: 1.4 Parameters ----------- ctx: :class:`.Context` The invocation context to retrieve the cooldown from. Returns -------- :class:`float` The amount of time left on this command's cooldown in seconds. If this is ``0.0`` then the command isn't on cooldown. """ if self._buckets.valid: bucket = self._buckets.get_bucket(ctx.message) dt = ctx.message.edited_at or ctx.message.created_at current = dt.replace(tzinfo=datetime.timezone.utc).timestamp() return bucket.get_retry_after(current) return 0.0
async def invoke(self, ctx): await self.prepare(ctx) # terminate the invoked_subcommand chain. # since we're in a regular command (and not a group) then # the invoked subcommand is None. ctx.invoked_subcommand = None ctx.subcommand_passed = None injected = hooked_wrapped_callback(self, ctx, self.callback) await injected(*ctx.args, **ctx.kwargs) async def reinvoke(self, ctx, *, call_hooks=False): ctx.command = self await self._parse_arguments(ctx) if call_hooks: await self.call_before_hooks(ctx) ctx.invoked_subcommand = None try: await self.callback(*ctx.args, **ctx.kwargs) except: ctx.command_failed = True raise finally: if call_hooks: await self.call_after_hooks(ctx) def error(self, coro): """A decorator that registers a coroutine as a local error handler. A local error handler is an :func:`.on_command_error` event limited to a single command. However, the :func:`.on_command_error` is still invoked afterwards as the catch-all. Parameters ----------- coro: :ref:`coroutine <coroutine>` The coroutine to register as the local error handler. Raises ------- TypeError The coroutine passed is not actually a coroutine. """ if not asyncio.iscoroutinefunction(coro): raise TypeError('The error handler must be a coroutine.') self.on_error = coro return coro
[docs] def has_error_handler(self): """:class:`bool`: Checks whether the command has an error handler registered. .. versionadded:: 1.7 """ return hasattr(self, 'on_error')
[docs] def before_invoke(self, coro): """A decorator that registers a coroutine as a pre-invoke hook. A pre-invoke hook is called directly before the command is called. This makes it a useful function to set up database connections or any type of set up required. This pre-invoke hook takes a sole parameter, a :class:`.Context`. See :meth:`.Bot.before_invoke` for more info. Parameters ----------- coro: :ref:`coroutine <coroutine>` The coroutine to register as the pre-invoke hook. Raises ------- TypeError The coroutine passed is not actually a coroutine. """ if not asyncio.iscoroutinefunction(coro): raise TypeError('The pre-invoke hook must be a coroutine.') self._before_invoke = coro return coro
[docs] def after_invoke(self, coro): """A decorator that registers a coroutine as a post-invoke hook. A post-invoke hook is called directly after the command is called. This makes it a useful function to clean-up database connections or any type of clean up required. This post-invoke hook takes a sole parameter, a :class:`.Context`. See :meth:`.Bot.after_invoke` for more info. Parameters ----------- coro: :ref:`coroutine <coroutine>` The coroutine to register as the post-invoke hook. Raises ------- TypeError The coroutine passed is not actually a coroutine. """ if not asyncio.iscoroutinefunction(coro): raise TypeError('The post-invoke hook must be a coroutine.') self._after_invoke = coro return coro
@property def cog_name(self): """Optional[:class:`str`]: The name of the cog this command belongs to, if any.""" return type(self.cog).__cog_name__ if self.cog is not None else None @property def short_doc(self): """:class:`str`: Gets the "short" documentation of a command. By default, this is the :attr:`brief` attribute. If that lookup leads to an empty string then the first line of the :attr:`help` attribute is used instead. """ if self.brief is not None: return self.brief if self.help is not None: return self.help.split('\n', 1)[0] return '' def _is_typing_optional(self, annotation): try: origin = annotation.__origin__ except AttributeError: return False if origin is not typing.Union: return False return annotation.__args__[-1] is type(None) @property def signature(self): """:class:`str`: Returns a POSIX-like signature useful for help command output.""" if self.usage is not None: return self.usage params = self.clean_params if not params: return '' result = [] for name, param in params.items(): greedy = isinstance(param.annotation, converters._Greedy) if param.default is not param.empty: # We don't want None or '' to trigger the [name=value] case and instead it should # do [name] since [name=None] or [name=] are not exactly useful for the user. should_print = param.default if isinstance(param.default, str) else param.default is not None if should_print: result.append('[%s=%s]' % (name, param.default) if not greedy else '[%s=%s]...' % (name, param.default)) continue else: result.append('[%s]' % name) elif param.kind == param.VAR_POSITIONAL: if self.require_var_positional: result.append('<%s...>' % name) else: result.append('[%s...]' % name) elif greedy: result.append('[%s]...' % name) elif self._is_typing_optional(param.annotation): result.append('[%s]' % name) else: result.append('<%s>' % name) return ' '.join(result) async def can_run(self, ctx): """|coro| Checks if the command can be executed by checking all the predicates inside the :attr:`checks` attribute. This also checks whether the command is disabled. .. versionchanged:: 1.3 Checks whether the command is disabled or not Parameters ----------- ctx: :class:`.Context` The ctx of the command currently being invoked. Raises ------- :class:`CommandError` Any command error that was raised during a check call will be propagated by this function. Returns -------- :class:`bool` A boolean indicating if the command can be invoked. """ if not self.enabled: raise DisabledCommand('{0.name} command is disabled'.format(self)) original = ctx.command ctx.command = self try: if not await ctx.bot.can_run(ctx): raise CheckFailure('The global check functions for command {0.qualified_name} failed.'.format(self)) cog = self.cog if cog is not None: local_check = Cog._get_overridden_method(cog.cog_check) if local_check is not None: ret = await discord.utils.maybe_coroutine(local_check, ctx) if not ret: return False predicates = self.checks if not predicates: # since we have no checks, then we just return True. return True return await discord.utils.async_all(predicate(ctx) for predicate in predicates) finally: ctx.command = original class GroupMixin: """A mixin that implements common functionality for classes that behave similar to :class:`.Group` and are allowed to register commands. Attributes ----------- all_commands: :class:`dict` A mapping of command name to :class:`.Command` objects. case_insensitive: :class:`bool` Whether the commands should be case insensitive. Defaults to ``False``. """ def __init__(self, *args, **kwargs): case_insensitive = kwargs.get('case_insensitive', False) self.all_commands = _CaseInsensitiveDict() if case_insensitive else {} self.case_insensitive = case_insensitive super().__init__(*args, **kwargs) @property def commands(self): """Set[:class:`.Command`]: A unique set of commands without aliases that are registered.""" return set(self.all_commands.values()) def recursively_remove_all_commands(self): for command in self.all_commands.copy().values(): if isinstance(command, GroupMixin): command.recursively_remove_all_commands() self.remove_command(command.name) def add_command(self, command): """Adds a :class:`.Command` into the internal list of commands. This is usually not called, instead the :meth:`~.GroupMixin.command` or :meth:`~.GroupMixin.group` shortcut decorators are used instead. .. versionchanged:: 1.4 Raise :exc:`.CommandRegistrationError` instead of generic :exc:`.ClientException` Parameters ----------- command: :class:`Command` The command to add. Raises ------- :exc:`.CommandRegistrationError` If the command or its alias is already registered by different command. TypeError If the command passed is not a subclass of :class:`.Command`. """ if not isinstance(command, Command): raise TypeError('The command passed must be a subclass of Command') if isinstance(self, Command): command.parent = self if command.name in self.all_commands: raise CommandRegistrationError(command.name) self.all_commands[command.name] = command for alias in command.aliases: if alias in self.all_commands: self.remove_command(command.name) raise CommandRegistrationError(alias, alias_conflict=True) self.all_commands[alias] = command def remove_command(self, name): """Remove a :class:`.Command` from the internal list of commands. This could also be used as a way to remove aliases. Parameters ----------- name: :class:`str` The name of the command to remove. Returns -------- Optional[:class:`.Command`] The command that was removed. If the name is not valid then ``None`` is returned instead. """ command = self.all_commands.pop(name, None) # does not exist if command is None: return None if name in command.aliases: # we're removing an alias so we don't want to remove the rest return command # we're not removing the alias so let's delete the rest of them. for alias in command.aliases: cmd = self.all_commands.pop(alias, None) # in the case of a CommandRegistrationError, an alias might conflict # with an already existing command. If this is the case, we want to # make sure the pre-existing command is not removed. if cmd not in (None, command): self.all_commands[alias] = cmd return command def walk_commands(self): """An iterator that recursively walks through all commands and subcommands. .. versionchanged:: 1.4 Duplicates due to aliases are no longer returned Yields ------ Union[:class:`.Command`, :class:`.Group`] A command or group from the internal list of commands. """ for command in self.commands: yield command if isinstance(command, GroupMixin): yield from command.walk_commands() def get_command(self, name): """Get a :class:`.Command` from the internal list of commands. This could also be used as a way to get aliases. The name could be fully qualified (e.g. ``'foo bar'``) will get the subcommand ``bar`` of the group command ``foo``. If a subcommand is not found then ``None`` is returned just as usual. Parameters ----------- name: :class:`str` The name of the command to get. Returns -------- Optional[:class:`Command`] The command that was requested. If not found, returns ``None``. """ # fast path, no space in name. if ' ' not in name: return self.all_commands.get(name) names = name.split() if not names: return None obj = self.all_commands.get(names[0]) if not isinstance(obj, GroupMixin): return obj for name in names[1:]: try: obj = obj.all_commands[name] except (AttributeError, KeyError): return None return obj def command(self, *args, **kwargs): """A shortcut decorator that invokes :func:`.command` and adds it to the internal command list via :meth:`~.GroupMixin.add_command`. Returns -------- Callable[..., :class:`Command`] A decorator that converts the provided method into a Command, adds it to the bot, then returns it. """ def decorator(func): kwargs.setdefault('parent', self) result = command(*args, **kwargs)(func) self.add_command(result) return result return decorator def group(self, *args, **kwargs): """A shortcut decorator that invokes :func:`.group` and adds it to the internal command list via :meth:`~.GroupMixin.add_command`. Returns -------- Callable[..., :class:`Group`] A decorator that converts the provided method into a Group, adds it to the bot, then returns it. """ def decorator(func): kwargs.setdefault('parent', self) result = group(*args, **kwargs)(func) self.add_command(result) return result return decorator class Group(GroupMixin, Command): """A class that implements a grouping protocol for commands to be executed as subcommands. This class is a subclass of :class:`.Command` and thus all options valid in :class:`.Command` are valid in here as well. Attributes ----------- invoke_without_command: :class:`bool` Indicates if the group callback should begin parsing and invocation only if no subcommand was found. Useful for making it an error handling function to tell the user that no subcommand was found or to have different functionality in case no subcommand was found. If this is ``False``, then the group callback will always be invoked first. This means that the checks and the parsing dictated by its parameters will be executed. Defaults to ``False``. case_insensitive: :class:`bool` Indicates if the group's commands should be case insensitive. Defaults to ``False``. """ def __init__(self, *args, **attrs): self.invoke_without_command = attrs.pop('invoke_without_command', False) super().__init__(*args, **attrs) def copy(self): """Creates a copy of this :class:`Group`. Returns -------- :class:`Group` A new instance of this group. """ ret = super().copy() for cmd in self.commands: ret.add_command(cmd.copy()) return ret async def invoke(self, ctx): ctx.invoked_subcommand = None ctx.subcommand_passed = None early_invoke = not self.invoke_without_command if early_invoke: await self.prepare(ctx) view = ctx.view previous = view.index view.skip_ws() trigger = view.get_word() if trigger: ctx.subcommand_passed = trigger ctx.invoked_subcommand = self.all_commands.get(trigger, None) if early_invoke: injected = hooked_wrapped_callback(self, ctx, self.callback) await injected(*ctx.args, **ctx.kwargs) ctx.invoked_parents.append(ctx.invoked_with) if trigger and ctx.invoked_subcommand: ctx.invoked_with = trigger await ctx.invoked_subcommand.invoke(ctx) elif not early_invoke: # undo the trigger parsing view.index = previous view.previous = previous await super().invoke(ctx) async def reinvoke(self, ctx, *, call_hooks=False): ctx.invoked_subcommand = None early_invoke = not self.invoke_without_command if early_invoke: ctx.command = self await self._parse_arguments(ctx) if call_hooks: await self.call_before_hooks(ctx) view = ctx.view previous = view.index view.skip_ws() trigger = view.get_word() if trigger: ctx.subcommand_passed = trigger ctx.invoked_subcommand = self.all_commands.get(trigger, None) if early_invoke: try: await self.callback(*ctx.args, **ctx.kwargs) except: ctx.command_failed = True raise finally: if call_hooks: await self.call_after_hooks(ctx) ctx.invoked_parents.append(ctx.invoked_with) if trigger and ctx.invoked_subcommand: ctx.invoked_with = trigger await ctx.invoked_subcommand.reinvoke(ctx, call_hooks=call_hooks) elif not early_invoke: # undo the trigger parsing view.index = previous view.previous = previous await super().reinvoke(ctx, call_hooks=call_hooks) # Decorators def command(name=None, cls=None, **attrs): """A decorator that transforms a function into a :class:`.Command` or if called with :func:`.group`, :class:`.Group`. By default the ``help`` attribute is received automatically from the docstring of the function and is cleaned up with the use of ``inspect.cleandoc``. If the docstring is ``bytes``, then it is decoded into :class:`str` using utf-8 encoding. All checks added using the :func:`.check` & co. decorators are added into the function. There is no way to supply your own checks through this decorator. Parameters ----------- name: :class:`str` The name to create the command with. By default this uses the function name unchanged. cls The class to construct with. By default this is :class:`.Command`. You usually do not change this. attrs Keyword arguments to pass into the construction of the class denoted by ``cls``. Raises ------- TypeError If the function is not a coroutine or is already a command. """ if cls is None: cls = Command def decorator(func): if isinstance(func, Command): raise TypeError('Callback is already a command.') return cls(func, name=name, **attrs) return decorator def group(name=None, **attrs): """A decorator that transforms a function into a :class:`.Group`. This is similar to the :func:`.command` decorator but the ``cls`` parameter is set to :class:`Group` by default. .. versionchanged:: 1.1 The ``cls`` parameter can now be passed. """ attrs.setdefault('cls', Group) return command(name=name, **attrs) def check(predicate): r"""A decorator that adds a check to the :class:`.Command` or its subclasses. These checks could be accessed via :attr:`.Command.checks`. These checks should be predicates that take in a single parameter taking a :class:`.Context`. If the check returns a ``False``\-like value then during invocation a :exc:`.CheckFailure` exception is raised and sent to the :func:`.on_command_error` event. If an exception should be thrown in the predicate then it should be a subclass of :exc:`.CommandError`. Any exception not subclassed from it will be propagated while those subclassed will be sent to :func:`.on_command_error`. A special attribute named ``predicate`` is bound to the value returned by this decorator to retrieve the predicate passed to the decorator. This allows the following introspection and chaining to be done: .. code-block:: python3 def owner_or_permissions(**perms): original = commands.has_permissions(**perms).predicate async def extended_check(ctx): if ctx.guild is None: return False return ctx.guild.owner_id == ctx.author.id or await original(ctx) return commands.check(extended_check) .. note:: The function returned by ``predicate`` is **always** a coroutine, even if the original function was not a coroutine. .. versionchanged:: 1.3 The ``predicate`` attribute was added. Examples --------- Creating a basic check to see if the command invoker is you. .. code-block:: python3 def check_if_it_is_me(ctx): return ctx.message.author.id == 85309593344815104 @bot.command() @commands.check(check_if_it_is_me) async def only_for_me(ctx): await ctx.send('I know you!') Transforming common checks into its own decorator: .. code-block:: python3 def is_me(): def predicate(ctx): return ctx.message.author.id == 85309593344815104 return commands.check(predicate) @bot.command() @is_me() async def only_me(ctx): await ctx.send('Only you!') Parameters ----------- predicate: Callable[[:class:`Context`], :class:`bool`] The predicate to check if the command should be invoked. """ def decorator(func): if isinstance(func, Command): func.checks.append(predicate) else: if not hasattr(func, '__commands_checks__'): func.__commands_checks__ = [] func.__commands_checks__.append(predicate) return func if inspect.iscoroutinefunction(predicate): decorator.predicate = predicate else: @functools.wraps(predicate) async def wrapper(ctx): return predicate(ctx) decorator.predicate = wrapper return decorator def check_any(*checks): r"""A :func:`check` that is added that checks if any of the checks passed will pass, i.e. using logical OR. If all checks fail then :exc:`.CheckAnyFailure` is raised to signal the failure. It inherits from :exc:`.CheckFailure`. .. note:: The ``predicate`` attribute for this function **is** a coroutine. .. versionadded:: 1.3 Parameters ------------ \*checks: Callable[[:class:`Context`], :class:`bool`] An argument list of checks that have been decorated with the :func:`check` decorator. Raises ------- TypeError A check passed has not been decorated with the :func:`check` decorator. Examples --------- Creating a basic check to see if it's the bot owner or the server owner: .. code-block:: python3 def is_guild_owner(): def predicate(ctx): return ctx.guild is not None and ctx.guild.owner_id == ctx.author.id return commands.check(predicate) @bot.command() @commands.check_any(commands.is_owner(), is_guild_owner()) async def only_for_owners(ctx): await ctx.send('Hello mister owner!') """ unwrapped = [] for wrapped in checks: try: pred = wrapped.predicate except AttributeError: raise TypeError('%r must be wrapped by commands.check decorator' % wrapped) from None else: unwrapped.append(pred) async def predicate(ctx): errors = [] for func in unwrapped: try: value = await func(ctx) except CheckFailure as e: errors.append(e) else: if value: return True # if we're here, all checks failed raise CheckAnyFailure(unwrapped, errors) return check(predicate) def has_role(item): """A :func:`.check` that is added that checks if the member invoking the command has the role specified via the name or ID specified. If a string is specified, you must give the exact name of the role, including caps and spelling. If an integer is specified, you must give the exact snowflake ID of the role. If the message is invoked in a private message context then the check will return ``False``. This check raises one of two special exceptions, :exc:`.MissingRole` if the user is missing a role, or :exc:`.NoPrivateMessage` if it is used in a private message. Both inherit from :exc:`.CheckFailure`. .. versionchanged:: 1.1 Raise :exc:`.MissingRole` or :exc:`.NoPrivateMessage` instead of generic :exc:`.CheckFailure` Parameters ----------- item: Union[:class:`int`, :class:`str`] The name or ID of the role to check. """ def predicate(ctx): if not isinstance(ctx.channel, discord.abc.GuildChannel): raise NoPrivateMessage() if isinstance(item, int): role = discord.utils.get(ctx.author.roles, id=item) else: role = discord.utils.get(ctx.author.roles, name=item) if role is None: raise MissingRole(item) return True return check(predicate) def has_any_role(*items): r"""A :func:`.check` that is added that checks if the member invoking the command has **any** of the roles specified. This means that if they have one out of the three roles specified, then this check will return `True`. Similar to :func:`.has_role`\, the names or IDs passed in must be exact. This check raises one of two special exceptions, :exc:`.MissingAnyRole` if the user is missing all roles, or :exc:`.NoPrivateMessage` if it is used in a private message. Both inherit from :exc:`.CheckFailure`. .. versionchanged:: 1.1 Raise :exc:`.MissingAnyRole` or :exc:`.NoPrivateMessage` instead of generic :exc:`.CheckFailure` Parameters ----------- items: List[Union[:class:`str`, :class:`int`]] An argument list of names or IDs to check that the member has roles wise. Example -------- .. code-block:: python3 @bot.command() @commands.has_any_role('Library Devs', 'Moderators', 492212595072434186) async def cool(ctx): await ctx.send('You are cool indeed') """ def predicate(ctx): if not isinstance(ctx.channel, discord.abc.GuildChannel): raise NoPrivateMessage() getter = functools.partial(discord.utils.get, ctx.author.roles) if any(getter(id=item) is not None if isinstance(item, int) else getter(name=item) is not None for item in items): return True raise MissingAnyRole(items) return check(predicate) def bot_has_role(item): """Similar to :func:`.has_role` except checks if the bot itself has the role. This check raises one of two special exceptions, :exc:`.BotMissingRole` if the bot is missing the role, or :exc:`.NoPrivateMessage` if it is used in a private message. Both inherit from :exc:`.CheckFailure`. .. versionchanged:: 1.1 Raise :exc:`.BotMissingRole` or :exc:`.NoPrivateMessage` instead of generic :exc:`.CheckFailure` """ def predicate(ctx): ch = ctx.channel if not isinstance(ch, discord.abc.GuildChannel): raise NoPrivateMessage() me = ch.guild.me if isinstance(item, int): role = discord.utils.get(me.roles, id=item) else: role = discord.utils.get(me.roles, name=item) if role is None: raise BotMissingRole(item) return True return check(predicate) def bot_has_any_role(*items): """Similar to :func:`.has_any_role` except checks if the bot itself has any of the roles listed. This check raises one of two special exceptions, :exc:`.BotMissingAnyRole` if the bot is missing all roles, or :exc:`.NoPrivateMessage` if it is used in a private message. Both inherit from :exc:`.CheckFailure`. .. versionchanged:: 1.1 Raise :exc:`.BotMissingAnyRole` or :exc:`.NoPrivateMessage` instead of generic checkfailure """ def predicate(ctx): ch = ctx.channel if not isinstance(ch, discord.abc.GuildChannel): raise NoPrivateMessage() me = ch.guild.me getter = functools.partial(discord.utils.get, me.roles) if any(getter(id=item) is not None if isinstance(item, int) else getter(name=item) is not None for item in items): return True raise BotMissingAnyRole(items) return check(predicate) def has_permissions(**perms): """A :func:`.check` that is added that checks if the member has all of the permissions necessary. Note that this check operates on the current channel permissions, not the guild wide permissions. The permissions passed in must be exactly like the properties shown under :class:`.discord.Permissions`. This check raises a special exception, :exc:`.MissingPermissions` that is inherited from :exc:`.CheckFailure`. Parameters ------------ perms An argument list of permissions to check for. Example --------- .. code-block:: python3 @bot.command() @commands.has_permissions(manage_messages=True) async def test(ctx): await ctx.send('You can manage messages.') """ invalid = set(perms) - set(discord.Permissions.VALID_FLAGS) if invalid: raise TypeError('Invalid permission(s): %s' % (', '.join(invalid))) def predicate(ctx): ch = ctx.channel permissions = ch.permissions_for(ctx.author) missing = [perm for perm, value in perms.items() if getattr(permissions, perm) != value] if not missing: return True raise MissingPermissions(missing) return check(predicate) def bot_has_permissions(**perms): """Similar to :func:`.has_permissions` except checks if the bot itself has the permissions listed. This check raises a special exception, :exc:`.BotMissingPermissions` that is inherited from :exc:`.CheckFailure`. """ invalid = set(perms) - set(discord.Permissions.VALID_FLAGS) if invalid: raise TypeError('Invalid permission(s): %s' % (', '.join(invalid))) def predicate(ctx): guild = ctx.guild me = guild.me if guild is not None else ctx.bot.user permissions = ctx.channel.permissions_for(me) missing = [perm for perm, value in perms.items() if getattr(permissions, perm) != value] if not missing: return True raise BotMissingPermissions(missing) return check(predicate) def has_guild_permissions(**perms): """Similar to :func:`.has_permissions`, but operates on guild wide permissions instead of the current channel permissions. If this check is called in a DM context, it will raise an exception, :exc:`.NoPrivateMessage`. .. versionadded:: 1.3 """ invalid = set(perms) - set(discord.Permissions.VALID_FLAGS) if invalid: raise TypeError('Invalid permission(s): %s' % (', '.join(invalid))) def predicate(ctx): if not ctx.guild: raise NoPrivateMessage permissions = ctx.author.guild_permissions missing = [perm for perm, value in perms.items() if getattr(permissions, perm) != value] if not missing: return True raise MissingPermissions(missing) return check(predicate) def bot_has_guild_permissions(**perms): """Similar to :func:`.has_guild_permissions`, but checks the bot members guild permissions. .. versionadded:: 1.3 """ invalid = set(perms) - set(discord.Permissions.VALID_FLAGS) if invalid: raise TypeError('Invalid permission(s): %s' % (', '.join(invalid))) def predicate(ctx): if not ctx.guild: raise NoPrivateMessage permissions = ctx.me.guild_permissions missing = [perm for perm, value in perms.items() if getattr(permissions, perm) != value] if not missing: return True raise BotMissingPermissions(missing) return check(predicate) def dm_only(): """A :func:`.check` that indicates this command must only be used in a DM context. Only private messages are allowed when using the command. This check raises a special exception, :exc:`.PrivateMessageOnly` that is inherited from :exc:`.CheckFailure`. .. versionadded:: 1.1 """ def predicate(ctx): if ctx.guild is not None: raise PrivateMessageOnly() return True return check(predicate) def guild_only(): """A :func:`.check` that indicates this command must only be used in a guild context only. Basically, no private messages are allowed when using the command. This check raises a special exception, :exc:`.NoPrivateMessage` that is inherited from :exc:`.CheckFailure`. """ def predicate(ctx): if ctx.guild is None: raise NoPrivateMessage() return True return check(predicate) def is_owner(): """A :func:`.check` that checks if the person invoking this command is the owner of the bot. This is powered by :meth:`.Bot.is_owner`. This check raises a special exception, :exc:`.NotOwner` that is derived from :exc:`.CheckFailure`. """ async def predicate(ctx): if not await ctx.bot.is_owner(ctx.author): raise NotOwner('You do not own this bot.') return True return check(predicate) def is_nsfw(): """A :func:`.check` that checks if the channel is a NSFW channel. This check raises a special exception, :exc:`.NSFWChannelRequired` that is derived from :exc:`.CheckFailure`. .. versionchanged:: 1.1 Raise :exc:`.NSFWChannelRequired` instead of generic :exc:`.CheckFailure`. DM channels will also now pass this check. """ def pred(ctx): ch = ctx.channel if ctx.guild is None or (isinstance(ch, discord.TextChannel) and ch.is_nsfw()): return True raise NSFWChannelRequired(ch) return check(pred) def cooldown(rate, per, type=BucketType.default): """A decorator that adds a cooldown to a :class:`.Command` A cooldown allows a command to only be used a specific amount of times in a specific time frame. These cooldowns can be based either on a per-guild, per-channel, per-user, per-role or global basis. Denoted by the third argument of ``type`` which must be of enum type :class:`.BucketType`. If a cooldown is triggered, then :exc:`.CommandOnCooldown` is triggered in :func:`.on_command_error` and the local error handler. A command can only have a single cooldown. Parameters ------------ rate: :class:`int` The number of times a command can be used before triggering a cooldown. per: :class:`float` The amount of seconds to wait for a cooldown when it's been triggered. type: Union[:class:`.BucketType`, Callable[[:class:`.Message`], Any]] The type of cooldown to have. If callable, should return a key for the mapping. .. versionchanged:: 1.7 Callables are now supported for custom bucket types. """ def decorator(func): if isinstance(func, Command): func._buckets = CooldownMapping(Cooldown(rate, per, type)) else: func.__commands_cooldown__ = Cooldown(rate, per, type) return func return decorator def max_concurrency(number, per=BucketType.default, *, wait=False): """A decorator that adds a maximum concurrency to a :class:`.Command` or its subclasses. This enables you to only allow a certain number of command invocations at the same time, for example if a command takes too long or if only one user can use it at a time. This differs from a cooldown in that there is no set waiting period or token bucket -- only a set number of people can run the command. .. versionadded:: 1.3 Parameters ------------- number: :class:`int` The maximum number of invocations of this command that can be running at the same time. per: :class:`.BucketType` The bucket that this concurrency is based on, e.g. ``BucketType.guild`` would allow it to be used up to ``number`` times per guild. wait: :class:`bool` Whether the command should wait for the queue to be over. If this is set to ``False`` then instead of waiting until the command can run again, the command raises :exc:`.MaxConcurrencyReached` to its error handler. If this is set to ``True`` then the command waits until it can be executed. """ def decorator(func): value = MaxConcurrency(number, per=per, wait=wait) if isinstance(func, Command): func._max_concurrency = value else: func.__commands_max_concurrency__ = value return func return decorator def before_invoke(coro): """A decorator that registers a coroutine as a pre-invoke hook. This allows you to refer to one before invoke hook for several commands that do not have to be within the same cog. .. versionadded:: 1.4 Example --------- .. code-block:: python3 async def record_usage(ctx): print(ctx.author, 'used', ctx.command, 'at', ctx.message.created_at) @bot.command() @commands.before_invoke(record_usage) async def who(ctx): # Output: <User> used who at <Time> await ctx.send('i am a bot') class What(commands.Cog): @commands.before_invoke(record_usage) @commands.command() async def when(self, ctx): # Output: <User> used when at <Time> await ctx.send('and i have existed since {}'.format(ctx.bot.user.created_at)) @commands.command() async def where(self, ctx): # Output: <Nothing> await ctx.send('on Discord') @commands.command() async def why(self, ctx): # Output: <Nothing> await ctx.send('because someone made me') bot.add_cog(What()) """ def decorator(func): if isinstance(func, Command): func.before_invoke(coro) else: func.__before_invoke__ = coro return func return decorator def after_invoke(coro): """A decorator that registers a coroutine as a post-invoke hook. This allows you to refer to one after invoke hook for several commands that do not have to be within the same cog. .. versionadded:: 1.4 """ def decorator(func): if isinstance(func, Command): func.after_invoke(coro) else: func.__after_invoke__ = coro return func return decorator