Add __slots__ (#2345)

Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>
Co-authored-by: Hinrich Mahler <hinrich.mahler@freenet.de>

telegram/base.py

@@ -26,6 +26,7 @@ import warnings
 from typing import TYPE_CHECKING, List, Optional, Tuple, Type, TypeVar
 
 from telegram.utils.types import JSONDict
+from telegram.utils.deprecate import set_new_attribute_deprecated
 
 if TYPE_CHECKING:
     from telegram import Bot
@@ -38,11 +39,19 @@ class TelegramObject:
 
     _id_attrs: Tuple[object, ...] = ()
 
+    # Adding slots reduces memory usage & allows for faster attribute access.
+    # Only instance variables should be added to __slots__.
+    # We add __dict__ here for backward compatibility & also to avoid repetition for subclasses.
+    __slots__ = ('__dict__',)
+
     def __str__(self) -> str:
         return str(self.to_dict())
 
     def __getitem__(self, item: str) -> object:
-        return self.__dict__[item]
+        return getattr(self, item, None)
+
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)
 
     @staticmethod
     def _parse_data(data: Optional[JSONDict]) -> Optional[JSONDict]:
@@ -102,11 +111,16 @@ class TelegramObject:
         """
         data = {}
 
-        for key in iter(self.__dict__):
+        # We want to get all attributes for the class, using self.__slots__ only includes the
+        # attributes used by that class itself, and not its superclass(es). Hence we get its MRO
+        # and then get their attributes. The `[:-2]` slice excludes the `object` class & the
+        # TelegramObject class itself.
+        attrs = {attr for cls in self.__class__.__mro__[:-2] for attr in cls.__slots__}
+        for key in attrs:
             if key == 'bot' or key.startswith('_'):
                 continue
 
-            value = self.__dict__[key]
+            value = getattr(self, key, None)
             if value is not None:
                 if hasattr(value, 'to_dict'):
                     data[key] = value.to_dict()

telegram/bot.py

@@ -158,6 +158,18 @@ class Bot(TelegramObject):
 
     """
 
+    __slots__ = (
+        'token',
+        'base_url',
+        'base_file_url',
+        'private_key',
+        'defaults',
+        '_bot',
+        '_commands',
+        '_request',
+        'logger',
+    )
+
     def __init__(
         self,
         token: str,
@@ -184,6 +196,7 @@ class Bot(TelegramObject):
         self._bot: Optional[User] = None
         self._commands: Optional[List[BotCommand]] = None
         self._request = request or Request()
+        self.private_key = None
         self.logger = logging.getLogger(__name__)
 
         if private_key:
@@ -196,6 +209,12 @@ class Bot(TelegramObject):
                 private_key, password=private_key_password, backend=default_backend()
             )
 
+    def __setattr__(self, key: str, value: object) -> None:
+        if issubclass(self.__class__, Bot) and self.__class__ is not Bot:
+            object.__setattr__(self, key, value)
+            return
+        super().__setattr__(key, value)
+
     def _insert_defaults(
         self, data: Dict[str, object], timeout: ODVInput[float]
     ) -> Optional[float]:

telegram/botcommand.py

@@ -41,6 +41,8 @@ class BotCommand(TelegramObject):
 
     """
 
+    __slots__ = ('description', '_id_attrs', 'command')
+
     def __init__(self, command: str, description: str, **_kwargs: Any):
         self.command = command
         self.description = description

telegram/callbackquery.py

@@ -85,6 +85,18 @@ class CallbackQuery(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bot',
+        'game_short_name',
+        'message',
+        'chat_instance',
+        'id',
+        'from_user',
+        'inline_message_id',
+        'data',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/chat.py

@@ -143,6 +143,30 @@ class Chat(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bio',
+        'id',
+        'type',
+        'last_name',
+        'bot',
+        'sticker_set_name',
+        'slow_mode_delay',
+        'location',
+        'first_name',
+        'permissions',
+        'invite_link',
+        'pinned_message',
+        'description',
+        'can_set_sticker_set',
+        'username',
+        'title',
+        'photo',
+        'linked_chat_id',
+        'all_members_are_administrators',
+        'message_auto_delete_time',
+        '_id_attrs',
+    )
+
     SENDER: ClassVar[str] = constants.CHAT_SENDER
     """:const:`telegram.constants.CHAT_SENDER`
 

telegram/chataction.py

@@ -20,11 +20,13 @@
 """This module contains an object that represents a Telegram ChatAction."""
 from typing import ClassVar
 from telegram import constants
+from telegram.utils.deprecate import set_new_attribute_deprecated
 
 
 class ChatAction:
     """Helper class to provide constants for different chat actions."""
 
+    __slots__ = ('__dict__',)  # Adding __dict__ here since it doesn't subclass TGObject
     FIND_LOCATION: ClassVar[str] = constants.CHATACTION_FIND_LOCATION
     """:const:`telegram.constants.CHATACTION_FIND_LOCATION`"""
     RECORD_AUDIO: ClassVar[str] = constants.CHATACTION_RECORD_AUDIO
@@ -65,3 +67,6 @@ class ChatAction:
     """:const:`telegram.constants.CHATACTION_UPLOAD_VIDEO`"""
     UPLOAD_VIDEO_NOTE: ClassVar[str] = constants.CHATACTION_UPLOAD_VIDEO_NOTE
     """:const:`telegram.constants.CHATACTION_UPLOAD_VIDEO_NOTE`"""
+
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)

telegram/chatinvitelink.py

@@ -60,6 +60,16 @@ class ChatInviteLink(TelegramObject):
 
     """
 
+    __slots__ = (
+        'invite_link',
+        'creator',
+        'is_primary',
+        'is_revoked',
+        'expire_date',
+        'member_limit',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         invite_link: str,

telegram/chatlocation.py

@@ -47,6 +47,8 @@ class ChatLocation(TelegramObject):
 
     """
 
+    __slots__ = ('location', '_id_attrs', 'address')
+
     def __init__(
         self,
         location: Location,

telegram/chatmember.py

@@ -138,6 +138,32 @@ class ChatMember(TelegramObject):
 
     """
 
+    __slots__ = (
+        'is_member',
+        'can_restrict_members',
+        'can_delete_messages',
+        'custom_title',
+        'can_be_edited',
+        'can_post_messages',
+        'can_send_messages',
+        'can_edit_messages',
+        'can_send_media_messages',
+        'is_anonymous',
+        'can_add_web_page_previews',
+        'can_send_other_messages',
+        'can_invite_users',
+        'can_send_polls',
+        'user',
+        'can_promote_members',
+        'status',
+        'can_change_info',
+        'can_pin_messages',
+        'can_manage_chat',
+        'can_manage_voice_chats',
+        'until_date',
+        '_id_attrs',
+    )
+
     ADMINISTRATOR: ClassVar[str] = constants.CHATMEMBER_ADMINISTRATOR
     """:const:`telegram.constants.CHATMEMBER_ADMINISTRATOR`"""
     CREATOR: ClassVar[str] = constants.CHATMEMBER_CREATOR

telegram/chatmemberupdated.py

@@ -62,6 +62,16 @@ class ChatMemberUpdated(TelegramObject):
 
     """
 
+    __slots__ = (
+        'chat',
+        'from_user',
+        'date',
+        'old_chat_member',
+        'new_chat_member',
+        'invite_link',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         chat: Chat,

telegram/chatpermissions.py

@@ -78,6 +78,18 @@ class ChatPermissions(TelegramObject):
 
     """
 
+    __slots__ = (
+        'can_send_other_messages',
+        'can_invite_users',
+        'can_send_polls',
+        '_id_attrs',
+        'can_send_messages',
+        'can_send_media_messages',
+        'can_change_info',
+        'can_pin_messages',
+        'can_add_web_page_previews',
+    )
+
     def __init__(
         self,
         can_send_messages: bool = None,

telegram/choseninlineresult.py

@@ -61,6 +61,8 @@ class ChosenInlineResult(TelegramObject):
 
     """
 
+    __slots__ = ('location', 'result_id', 'from_user', 'inline_message_id', '_id_attrs', 'query')
+
     def __init__(
         self,
         result_id: str,

telegram/dice.py

@@ -64,6 +64,8 @@ class Dice(TelegramObject):
 
     """
 
+    __slots__ = ('emoji', 'value', '_id_attrs')
+
     def __init__(self, value: int, emoji: str, **_kwargs: Any):
         self.value = value
         self.emoji = emoji

telegram/error.py

@@ -41,6 +41,9 @@ def _lstrip_str(in_s: str, lstr: str) -> str:
 class TelegramError(Exception):
     """Base class for Telegram errors."""
 
+    # Apparently the base class Exception already has __dict__ in it, so its not included here
+    __slots__ = ('message',)
+
     def __init__(self, message: str):
         super().__init__()
 
@@ -62,10 +65,14 @@ class TelegramError(Exception):
 class Unauthorized(TelegramError):
     """Raised when the bot has not enough rights to perform the requested action."""
 
+    __slots__ = ()
+
 
 class InvalidToken(TelegramError):
     """Raised when the token is invalid."""
 
+    __slots__ = ()
+
     def __init__(self) -> None:
         super().__init__('Invalid token')
 
@@ -76,14 +83,20 @@ class InvalidToken(TelegramError):
 class NetworkError(TelegramError):
     """Base class for exceptions due to networking errors."""
 
+    __slots__ = ()
+
 
 class BadRequest(NetworkError):
     """Raised when Telegram could not process the request correctly."""
 
+    __slots__ = ()
+
 
 class TimedOut(NetworkError):
     """Raised when a request took too long to finish."""
 
+    __slots__ = ()
+
     def __init__(self) -> None:
         super().__init__('Timed out')
 
@@ -100,6 +113,8 @@ class ChatMigrated(TelegramError):
 
     """
 
+    __slots__ = ('new_chat_id',)
+
     def __init__(self, new_chat_id: int):
         super().__init__(f'Group migrated to supergroup. New chat id: {new_chat_id}')
         self.new_chat_id = new_chat_id
@@ -117,6 +132,8 @@ class RetryAfter(TelegramError):
 
     """
 
+    __slots__ = ('retry_after',)
+
     def __init__(self, retry_after: int):
         super().__init__(f'Flood control exceeded. Retry in {float(retry_after)} seconds')
         self.retry_after = float(retry_after)
@@ -128,5 +145,7 @@ class RetryAfter(TelegramError):
 class Conflict(TelegramError):
     """Raised when a long poll or webhook conflicts with another one."""
 
+    __slots__ = ()
+
     def __reduce__(self) -> Tuple[type, Tuple[str]]:
         return self.__class__, (self.message,)

telegram/ext/basepersistence.py

@@ -18,10 +18,13 @@
 # along with this program.  If not, see [http://www.gnu.org/licenses/].
 """This module contains the BasePersistence class."""
 import warnings
+from sys import version_info as py_ver
 from abc import ABC, abstractmethod
 from copy import copy
 from typing import DefaultDict, Dict, Optional, Tuple, cast, ClassVar
 
+from telegram.utils.deprecate import set_new_attribute_deprecated
+
 from telegram import Bot
 
 from telegram.utils.types import ConversationDict
@@ -75,6 +78,18 @@ class BasePersistence(ABC):
             persistence class.
     """
 
+    # Apparently Py 3.7 and below have '__dict__' in ABC
+    if py_ver < (3, 7):
+        __slots__ = ('store_user_data', 'store_chat_data', 'store_bot_data', 'bot')
+    else:
+        __slots__ = (
+            'store_user_data',  # type: ignore[assignment]
+            'store_chat_data',
+            'store_bot_data',
+            'bot',
+            '__dict__',
+        )
+
     def __new__(
         cls, *args: object, **kwargs: object  # pylint: disable=W0613
     ) -> 'BasePersistence':
@@ -104,12 +119,13 @@ class BasePersistence(ABC):
         def update_bot_data_replace_bot(data: Dict) -> None:
             return update_bot_data(instance.replace_bot(data))
 
-        instance.get_user_data = get_user_data_insert_bot
+        # We want to ignore TGDeprecation warnings so we use obj.__setattr__. Adds to __dict__
-        instance.get_chat_data = get_chat_data_insert_bot
+        object.__setattr__(instance, 'get_user_data', get_user_data_insert_bot)
-        instance.get_bot_data = get_bot_data_insert_bot
+        object.__setattr__(instance, 'get_chat_data', get_chat_data_insert_bot)
-        instance.update_user_data = update_user_data_replace_bot
+        object.__setattr__(instance, 'get_bot_data', get_bot_data_insert_bot)
-        instance.update_chat_data = update_chat_data_replace_bot
+        object.__setattr__(instance, 'update_user_data', update_user_data_replace_bot)
-        instance.update_bot_data = update_bot_data_replace_bot
+        object.__setattr__(instance, 'update_chat_data', update_chat_data_replace_bot)
+        object.__setattr__(instance, 'update_bot_data', update_bot_data_replace_bot)
         return instance
 
     def __init__(
@@ -123,6 +139,16 @@ class BasePersistence(ABC):
         self.store_bot_data = store_bot_data
         self.bot: Bot = None  # type: ignore[assignment]
 
+    def __setattr__(self, key: str, value: object) -> None:
+        # Allow user defined subclasses to have custom attributes.
+        if issubclass(self.__class__, BasePersistence) and self.__class__.__name__ not in {
+            'DictPersistence',
+            'PicklePersistence',
+        }:
+            object.__setattr__(self, key, value)
+            return
+        set_new_attribute_deprecated(self, key, value)
+
     def set_bot(self, bot: Bot) -> None:
         """Set the Bot to be used by this persistence instance.
 

telegram/ext/callbackcontext.py

@@ -73,6 +73,20 @@ class CallbackContext:
 
     """
 
+    __slots__ = (
+        '_dispatcher',
+        '_bot_data',
+        '_chat_data',
+        '_user_data',
+        'args',
+        'matches',
+        'error',
+        'job',
+        'async_args',
+        'async_kwargs',
+        '__dict__',
+    )
+
     def __init__(self, dispatcher: 'Dispatcher'):
         """
         Args:
@@ -229,12 +243,13 @@ class CallbackContext:
         return self
 
     def update(self, data: Dict[str, object]) -> None:
-        """Updates ``self.__dict__`` with the passed data.
+        """Updates ``self.__slots__`` with the passed data.
 
         Args:
             data (Dict[:obj:`str`, :obj:`object`]): The data.
         """
-        self.__dict__.update(data)
+        for key, value in data.items():
+            setattr(self, key, value)
 
     @property
     def bot(self) -> 'Bot':

telegram/ext/callbackqueryhandler.py

@@ -120,6 +120,8 @@ class CallbackQueryHandler(Handler[Update]):
 
     """
 
+    __slots__ = ('pattern', 'pass_groups', 'pass_groupdict')
+
     def __init__(
         self,
         callback: Callable[[Update, 'CallbackContext'], RT],

telegram/ext/chatmemberhandler.py

@@ -96,6 +96,7 @@ class ChatMemberHandler(Handler[Update]):
 
     """
 
+    __slots__ = ('chat_member_types',)
     MY_CHAT_MEMBER: ClassVar[int] = -1
     """:obj:`int`: Used as a constant to handle only :attr:`telegram.Update.my_chat_member`."""
     CHAT_MEMBER: ClassVar[int] = 0

telegram/ext/choseninlineresulthandler.py

@@ -99,6 +99,8 @@ class ChosenInlineResultHandler(Handler[Update]):
 
     """
 
+    __slots__ = ('pattern',)
+
     def __init__(
         self,
         callback: Callable[[Update, 'CallbackContext'], RT],

telegram/ext/commandhandler.py

@@ -129,6 +129,8 @@ class CommandHandler(Handler[Update]):
         run_async (:obj:`bool`): Determines whether the callback will run asynchronously.
     """
 
+    __slots__ = ('command', 'filters', 'pass_args')
+
     def __init__(
         self,
         command: SLT[str],
@@ -350,6 +352,9 @@ class PrefixHandler(CommandHandler):
 
     """
 
+    # 'prefix' is a class property, & 'command' is included in the superclass, so they're left out.
+    __slots__ = ('_prefix', '_command', '_commands')
+
     def __init__(
         self,
         prefix: SLT[str],

telegram/ext/conversationhandler.py

@@ -45,6 +45,9 @@ CheckUpdateType = Optional[Tuple[Tuple[int, ...], Handler, object]]
 
 
 class _ConversationTimeoutContext:
+    # '__dict__' is not included since this a private class
+    __slots__ = ('conversation_key', 'update', 'dispatcher', 'callback_context')
+
     def __init__(
         self,
         conversation_key: Tuple[int, ...],
@@ -182,6 +185,26 @@ class ConversationHandler(Handler[Update]):
 
     """
 
+    __slots__ = (
+        '_entry_points',
+        '_states',
+        '_fallbacks',
+        '_allow_reentry',
+        '_per_user',
+        '_per_chat',
+        '_per_message',
+        '_conversation_timeout',
+        '_name',
+        'persistent',
+        '_persistence',
+        '_map_to_parent',
+        'timeout_jobs',
+        '_timeout_jobs_lock',
+        '_conversations',
+        '_conversations_lock',
+        'logger',
+    )
+
     END: ClassVar[int] = -1
     """:obj:`int`: Used as a constant to return when a conversation is ended."""
     TIMEOUT: ClassVar[int] = -2

telegram/ext/defaults.py

@@ -22,6 +22,7 @@ from typing import NoReturn, Optional, Dict, Any
 
 import pytz
 
+from telegram.utils.deprecate import set_new_attribute_deprecated
 from telegram.utils.helpers import DEFAULT_NONE
 from telegram.utils.types import ODVInput
 
@@ -56,6 +57,19 @@ class Defaults:
             :meth:`Dispatcher.add_error_handler`. Defaults to :obj:`False`.
     """
 
+    __slots__ = (
+        '_timeout',
+        '_tzinfo',
+        '_disable_web_page_preview',
+        '_run_async',
+        '_quote',
+        '_disable_notification',
+        '_allow_sending_without_reply',
+        '_parse_mode',
+        '_api_defaults',
+        '__dict__',
+    )
+
     def __init__(
         self,
         parse_mode: str = None,
@@ -91,8 +105,11 @@ class Defaults:
             if value not in [None, DEFAULT_NONE]:
                 self._api_defaults[kwarg] = value
         # Special casing, as None is a valid default value
-        if self.timeout != DEFAULT_NONE:
+        if self._timeout != DEFAULT_NONE:
-            self._api_defaults['timeout'] = self.timeout
+            self._api_defaults['timeout'] = self._timeout
+
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)
 
     @property
     def api_defaults(self) -> Dict[str, Any]:  # skip-cq: PY-D0003
@@ -243,7 +260,7 @@ class Defaults:
 
     def __eq__(self, other: object) -> bool:
         if isinstance(other, Defaults):
-            return self.__dict__ == other.__dict__
+            return all(getattr(self, attr) == getattr(other, attr) for attr in self.__slots__)
         return False
 
     def __ne__(self, other: object) -> bool:

telegram/ext/dictpersistence.py

@@ -79,6 +79,17 @@ class DictPersistence(BasePersistence):
             persistence class.
     """
 
+    __slots__ = (
+        '_user_data',
+        '_chat_data',
+        '_bot_data',
+        '_conversations',
+        '_user_data_json',
+        '_chat_data_json',
+        '_bot_data_json',
+        '_conversations_json',
+    )
+
     def __init__(
         self,
         store_user_data: bool = True,

telegram/ext/dispatcher.py

@@ -26,14 +26,14 @@ from functools import wraps
 from queue import Empty, Queue
 from threading import BoundedSemaphore, Event, Lock, Thread, current_thread
 from time import sleep
-from typing import TYPE_CHECKING, Callable, DefaultDict, Dict, List, Optional, Set, Union
+from typing import TYPE_CHECKING, Callable, DefaultDict, Dict, List, Optional, Union, Set
 from uuid import uuid4
 
 from telegram import TelegramError, Update
 from telegram.ext import BasePersistence
 from telegram.ext.callbackcontext import CallbackContext
 from telegram.ext.handler import Handler
-from telegram.utils.deprecate import TelegramDeprecationWarning
+from telegram.utils.deprecate import TelegramDeprecationWarning, set_new_attribute_deprecated
 from telegram.ext.utils.promise import Promise
 from telegram.utils.helpers import DefaultValue, DEFAULT_FALSE
 
@@ -98,6 +98,8 @@ class DispatcherHandlerStop(Exception):
         state (:obj:`object`, optional): The next state of the conversation.
     """
 
+    __slots__ = ('state',)
+
     def __init__(self, state: object = None) -> None:
         super().__init__()
         self.state = state
@@ -134,6 +136,30 @@ class Dispatcher:
 
     """
 
+    # Allowing '__weakref__' creation here since we need it for the singleton
+    __slots__ = (
+        'workers',
+        'persistence',
+        'use_context',
+        'update_queue',
+        'job_queue',
+        'user_data',
+        'chat_data',
+        'bot_data',
+        '_update_persistence_lock',
+        'handlers',
+        'groups',
+        'error_handlers',
+        'running',
+        '__stop_event',
+        '__exception_event',
+        '__async_queue',
+        '__async_threads',
+        'bot',
+        '__dict__',
+        '__weakref__',
+    )
+
     __singleton_lock = Lock()
     __singleton_semaphore = BoundedSemaphore()
     __singleton = None
@@ -215,6 +241,17 @@ class Dispatcher:
             else:
                 self._set_singleton(None)
 
+    def __setattr__(self, key: str, value: object) -> None:
+        # Mangled names don't automatically apply in __setattr__ (see
+        # https://docs.python.org/3/tutorial/classes.html#private-variables), so we have to make
+        # it mangled so they don't raise TelegramDeprecationWarning unnecessarily
+        if key.startswith('__'):
+            key = f"_{self.__class__.__name__}{key}"
+        if issubclass(self.__class__, Dispatcher) and self.__class__ is not Dispatcher:
+            object.__setattr__(self, key, value)
+            return
+        set_new_attribute_deprecated(self, key, value)
+
     @property
     def exception_event(self) -> Event:  # skipcq: PY-D0003
         return self.__exception_event

telegram/ext/filters.py

@@ -23,6 +23,7 @@ import re
 import warnings
 
 from abc import ABC, abstractmethod
+from sys import version_info as py_ver
 from threading import Lock
 from typing import (
     Dict,
@@ -50,7 +51,7 @@ __all__ = [
     'XORFilter',
 ]
 
-from telegram.utils.deprecate import TelegramDeprecationWarning
+from telegram.utils.deprecate import TelegramDeprecationWarning, set_new_attribute_deprecated
 from telegram.utils.types import SLT
 
 DataDict = Dict[str, list]
@@ -112,8 +113,17 @@ class BaseFilter(ABC):
             (depends on the handler).
     """
 
-    _name = None
+    if py_ver < (3, 7):
-    data_filter = False
+        __slots__ = ('_name', '_data_filter')
+    else:
+        __slots__ = ('_name', '_data_filter', '__dict__')  # type: ignore[assignment]
+
+    def __new__(cls, *args: object, **kwargs: object) -> 'BaseFilter':  # pylint: disable=W0613
+        instance = super().__new__(cls)
+        instance._name = None
+        instance._data_filter = False
+
+        return instance
 
     @abstractmethod
     def __call__(self, update: Update) -> Optional[Union[bool, DataDict]]:
@@ -131,13 +141,33 @@ class BaseFilter(ABC):
     def __invert__(self) -> 'BaseFilter':
         return InvertedFilter(self)
 
+    def __setattr__(self, key: str, value: object) -> None:
+        # Allow setting custom attributes w/o warning for user defined custom filters.
+        # To differentiate between a custom and a PTB filter, we use this hacky but
+        # simple way of checking the module name where the class is defined from.
+        if (
+            issubclass(self.__class__, (UpdateFilter, MessageFilter))
+            and self.__class__.__module__ != __name__
+        ):  # __name__ is telegram.ext.filters
+            object.__setattr__(self, key, value)
+            return
+        set_new_attribute_deprecated(self, key, value)
+
+    @property
+    def data_filter(self) -> bool:
+        return self._data_filter
+
+    @data_filter.setter
+    def data_filter(self, value: bool) -> None:
+        self._data_filter = value
+
     @property
     def name(self) -> Optional[str]:
         return self._name
 
     @name.setter
     def name(self, name: Optional[str]) -> None:
-        self._name = name
+        self._name = name  # pylint: disable=E0237
 
     def __repr__(self) -> str:
         # We do this here instead of in a __init__ so filter don't have to call __init__ or super()
@@ -146,7 +176,7 @@ class BaseFilter(ABC):
         return self.name
 
 
-class MessageFilter(BaseFilter, ABC):
+class MessageFilter(BaseFilter):
     """Base class for all Message Filters. In contrast to :class:`UpdateFilter`, the object passed
     to :meth:`filter` is ``update.effective_message``.
 
@@ -162,6 +192,8 @@ class MessageFilter(BaseFilter, ABC):
 
     """
 
+    __slots__ = ()
+
     def __call__(self, update: Update) -> Optional[Union[bool, DataDict]]:
         return self.filter(update.effective_message)
 
@@ -178,7 +210,7 @@ class MessageFilter(BaseFilter, ABC):
         """
 
 
-class UpdateFilter(BaseFilter, ABC):
+class UpdateFilter(BaseFilter):
     """Base class for all Update Filters. In contrast to :class:`MessageFilter`, the object
     passed to :meth:`filter` is ``update``, which allows to create filters like
     :attr:`Filters.update.edited_message`.
@@ -195,6 +227,8 @@ class UpdateFilter(BaseFilter, ABC):
 
     """
 
+    __slots__ = ()
+
     def __call__(self, update: Update) -> Optional[Union[bool, DataDict]]:
         return self.filter(update)
 
@@ -219,6 +253,8 @@ class InvertedFilter(UpdateFilter):
 
     """
 
+    __slots__ = ('f',)
+
     def __init__(self, f: BaseFilter):
         self.f = f
 
@@ -244,6 +280,8 @@ class MergedFilter(UpdateFilter):
 
     """
 
+    __slots__ = ('base_filter', 'and_filter', 'or_filter')
+
     def __init__(
         self, base_filter: BaseFilter, and_filter: BaseFilter = None, or_filter: BaseFilter = None
     ):
@@ -328,6 +366,8 @@ class XORFilter(UpdateFilter):
 
     """
 
+    __slots__ = ('base_filter', 'xor_filter', 'merged_filter')
+
     def __init__(self, base_filter: BaseFilter, xor_filter: BaseFilter):
         self.base_filter = base_filter
         self.xor_filter = xor_filter
@@ -346,11 +386,15 @@ class XORFilter(UpdateFilter):
 
 
 class _DiceEmoji(MessageFilter):
+    __slots__ = ('emoji',)
+
     def __init__(self, emoji: str = None, name: str = None):
         self.name = f'Filters.dice.{name}' if name else 'Filters.dice'
         self.emoji = emoji
 
     class _DiceValues(MessageFilter):
+        __slots__ = ('values', 'emoji')
+
         def __init__(
             self,
             values: SLT[int],
@@ -393,7 +437,13 @@ class Filters:
 
     """
 
+    __slots__ = ('__dict__',)
+
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)
+
     class _All(MessageFilter):
+        __slots__ = ()
         name = 'Filters.all'
 
         def filter(self, message: Message) -> bool:
@@ -403,9 +453,12 @@ class Filters:
     """All Messages."""
 
     class _Text(MessageFilter):
+        __slots__ = ()
         name = 'Filters.text'
 
         class _TextStrings(MessageFilter):
+            __slots__ = ('strings',)
+
             def __init__(self, strings: Union[List[str], Tuple[str]]):
                 self.strings = strings
                 self.name = f'Filters.text({strings})'
@@ -454,9 +507,12 @@ class Filters:
     """
 
     class _Caption(MessageFilter):
+        __slots__ = ()
         name = 'Filters.caption'
 
         class _CaptionStrings(MessageFilter):
+            __slots__ = ('strings',)
+
             def __init__(self, strings: Union[List[str], Tuple[str]]):
                 self.strings = strings
                 self.name = f'Filters.caption({strings})'
@@ -489,9 +545,12 @@ class Filters:
     """
 
     class _Command(MessageFilter):
+        __slots__ = ()
         name = 'Filters.command'
 
         class _CommandOnlyStart(MessageFilter):
+            __slots__ = ('only_start',)
+
             def __init__(self, only_start: bool):
                 self.only_start = only_start
                 self.name = f'Filters.command({only_start})'
@@ -564,6 +623,7 @@ class Filters:
             pattern (:obj:`str` | :obj:`Pattern`): The regex pattern.
         """
 
+        __slots__ = ('pattern',)
         data_filter = True
 
         def __init__(self, pattern: Union[str, Pattern]):
@@ -599,6 +659,7 @@ class Filters:
             pattern (:obj:`str` | :obj:`Pattern`): The regex pattern.
         """
 
+        __slots__ = ('pattern',)
         data_filter = True
 
         def __init__(self, pattern: Union[str, Pattern]):
@@ -617,6 +678,7 @@ class Filters:
             return {}
 
     class _Reply(MessageFilter):
+        __slots__ = ()
         name = 'Filters.reply'
 
         def filter(self, message: Message) -> bool:
@@ -626,6 +688,7 @@ class Filters:
     """Messages that are a reply to another message."""
 
     class _Audio(MessageFilter):
+        __slots__ = ()
         name = 'Filters.audio'
 
         def filter(self, message: Message) -> bool:
@@ -635,6 +698,7 @@ class Filters:
     """Messages that contain :class:`telegram.Audio`."""
 
     class _Document(MessageFilter):
+        __slots__ = ()
         name = 'Filters.document'
 
         class category(MessageFilter):
@@ -651,7 +715,14 @@ class Filters:
                 of audio sent as file, for example 'audio/mpeg' or 'audio/x-wav'.
             """
 
+            __slots__ = ('_category',)
+
             def __init__(self, category: Optional[str]):
+                """Initialize the category you want to filter
+
+                Args:
+                    category (str, optional): category of the media you want to filter
+                """
                 self._category = category
                 self.name = f"Filters.document.category('{self._category}')"
 
@@ -680,6 +751,8 @@ class Filters:
                 ``Filters.document.mime_type('audio/mpeg')`` filters all audio in mp3 format.
             """
 
+            __slots__ = ('mimetype',)
+
             def __init__(self, mimetype: Optional[str]):
                 self.mimetype = mimetype
                 self.name = f"Filters.document.mime_type('{self.mimetype}')"
@@ -732,6 +805,8 @@ class Filters:
                   filters files without a dot in the filename.
             """
 
+            __slots__ = ('_file_extension', 'is_case_sensitive')
+
             def __init__(self, file_extension: Optional[str], case_sensitive: bool = False):
                 """Initialize the extension you want to filter.
 
@@ -850,6 +925,7 @@ officedocument.wordprocessingml.document")``.
     """
 
     class _Animation(MessageFilter):
+        __slots__ = ()
         name = 'Filters.animation'
 
         def filter(self, message: Message) -> bool:
@@ -859,6 +935,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.Animation`."""
 
     class _Photo(MessageFilter):
+        __slots__ = ()
         name = 'Filters.photo'
 
         def filter(self, message: Message) -> bool:
@@ -868,6 +945,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.PhotoSize`."""
 
     class _Sticker(MessageFilter):
+        __slots__ = ()
         name = 'Filters.sticker'
 
         def filter(self, message: Message) -> bool:
@@ -877,6 +955,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.Sticker`."""
 
     class _Video(MessageFilter):
+        __slots__ = ()
         name = 'Filters.video'
 
         def filter(self, message: Message) -> bool:
@@ -886,6 +965,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.Video`."""
 
     class _Voice(MessageFilter):
+        __slots__ = ()
         name = 'Filters.voice'
 
         def filter(self, message: Message) -> bool:
@@ -895,6 +975,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.Voice`."""
 
     class _VideoNote(MessageFilter):
+        __slots__ = ()
         name = 'Filters.video_note'
 
         def filter(self, message: Message) -> bool:
@@ -904,6 +985,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.VideoNote`."""
 
     class _Contact(MessageFilter):
+        __slots__ = ()
         name = 'Filters.contact'
 
         def filter(self, message: Message) -> bool:
@@ -913,6 +995,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.Contact`."""
 
     class _Location(MessageFilter):
+        __slots__ = ()
         name = 'Filters.location'
 
         def filter(self, message: Message) -> bool:
@@ -922,6 +1005,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.Location`."""
 
     class _Venue(MessageFilter):
+        __slots__ = ()
         name = 'Filters.venue'
 
         def filter(self, message: Message) -> bool:
@@ -939,7 +1023,10 @@ officedocument.wordprocessingml.document")``.
 
         """
 
+        __slots__ = ()
+
         class _NewChatMembers(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.new_chat_members'
 
             def filter(self, message: Message) -> bool:
@@ -949,6 +1036,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.new_chat_members`."""
 
         class _LeftChatMember(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.left_chat_member'
 
             def filter(self, message: Message) -> bool:
@@ -958,6 +1046,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.left_chat_member`."""
 
         class _NewChatTitle(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.new_chat_title'
 
             def filter(self, message: Message) -> bool:
@@ -967,6 +1056,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.new_chat_title`."""
 
         class _NewChatPhoto(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.new_chat_photo'
 
             def filter(self, message: Message) -> bool:
@@ -976,6 +1066,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.new_chat_photo`."""
 
         class _DeleteChatPhoto(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.delete_chat_photo'
 
             def filter(self, message: Message) -> bool:
@@ -985,6 +1076,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.delete_chat_photo`."""
 
         class _ChatCreated(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.chat_created'
 
             def filter(self, message: Message) -> bool:
@@ -1000,6 +1092,7 @@ officedocument.wordprocessingml.document")``.
             :attr: `telegram.Message.channel_chat_created`."""
 
         class _MessageAutoDeleteTimerChanged(MessageFilter):
+            __slots__ = ()
             name = 'MessageAutoDeleteTimerChanged'
 
             def filter(self, message: Message) -> bool:
@@ -1009,6 +1102,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`message_auto_delete_timer_changed`"""
 
         class _Migrate(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.migrate'
 
             def filter(self, message: Message) -> bool:
@@ -1019,6 +1113,7 @@ officedocument.wordprocessingml.document")``.
             :attr:`telegram.Message.migrate_to_chat_id`."""
 
         class _PinnedMessage(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.pinned_message'
 
             def filter(self, message: Message) -> bool:
@@ -1028,6 +1123,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.pinned_message`."""
 
         class _ConnectedWebsite(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.connected_website'
 
             def filter(self, message: Message) -> bool:
@@ -1037,6 +1133,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.connected_website`."""
 
         class _ProximityAlertTriggered(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.proximity_alert_triggered'
 
             def filter(self, message: Message) -> bool:
@@ -1046,6 +1143,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.proximity_alert_triggered`."""
 
         class _VoiceChatScheduled(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.voice_chat_scheduled'
 
             def filter(self, message: Message) -> bool:
@@ -1055,6 +1153,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.voice_chat_scheduled`."""
 
         class _VoiceChatStarted(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.voice_chat_started'
 
             def filter(self, message: Message) -> bool:
@@ -1064,6 +1163,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.voice_chat_started`."""
 
         class _VoiceChatEnded(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.voice_chat_ended'
 
             def filter(self, message: Message) -> bool:
@@ -1073,6 +1173,7 @@ officedocument.wordprocessingml.document")``.
         """Messages that contain :attr:`telegram.Message.voice_chat_ended`."""
 
         class _VoiceChatParticipantsInvited(MessageFilter):
+            __slots__ = ()
             name = 'Filters.status_update.voice_chat_participants_invited'
 
             def filter(self, message: Message) -> bool:
@@ -1157,6 +1258,7 @@ officedocument.wordprocessingml.document")``.
     """
 
     class _Forwarded(MessageFilter):
+        __slots__ = ()
         name = 'Filters.forwarded'
 
         def filter(self, message: Message) -> bool:
@@ -1166,6 +1268,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that are forwarded."""
 
     class _Game(MessageFilter):
+        __slots__ = ()
         name = 'Filters.game'
 
         def filter(self, message: Message) -> bool:
@@ -1188,6 +1291,8 @@ officedocument.wordprocessingml.document")``.
 
         """
 
+        __slots__ = ('entity_type',)
+
         def __init__(self, entity_type: str):
             self.entity_type = entity_type
             self.name = f'Filters.entity({self.entity_type})'
@@ -1210,6 +1315,8 @@ officedocument.wordprocessingml.document")``.
 
         """
 
+        __slots__ = ('entity_type',)
+
         def __init__(self, entity_type: str):
             self.entity_type = entity_type
             self.name = f'Filters.caption_entity({self.entity_type})'
@@ -1219,6 +1326,7 @@ officedocument.wordprocessingml.document")``.
             return any(entity.type == self.entity_type for entity in message.caption_entities)
 
     class _Private(MessageFilter):
+        __slots__ = ()
         name = 'Filters.private'
 
         def filter(self, message: Message) -> bool:
@@ -1239,6 +1347,7 @@ officedocument.wordprocessingml.document")``.
     """
 
     class _Group(MessageFilter):
+        __slots__ = ()
         name = 'Filters.group'
 
         def filter(self, message: Message) -> bool:
@@ -1259,9 +1368,11 @@ officedocument.wordprocessingml.document")``.
     """
 
     class _ChatType(MessageFilter):
+        __slots__ = ()
         name = 'Filters.chat_type'
 
         class _Channel(MessageFilter):
+            __slots__ = ()
             name = 'Filters.chat_type.channel'
 
             def filter(self, message: Message) -> bool:
@@ -1270,6 +1381,7 @@ officedocument.wordprocessingml.document")``.
         channel = _Channel()
 
         class _Group(MessageFilter):
+            __slots__ = ()
             name = 'Filters.chat_type.group'
 
             def filter(self, message: Message) -> bool:
@@ -1278,6 +1390,7 @@ officedocument.wordprocessingml.document")``.
         group = _Group()
 
         class _SuperGroup(MessageFilter):
+            __slots__ = ()
             name = 'Filters.chat_type.supergroup'
 
             def filter(self, message: Message) -> bool:
@@ -1286,6 +1399,7 @@ officedocument.wordprocessingml.document")``.
         supergroup = _SuperGroup()
 
         class _Groups(MessageFilter):
+            __slots__ = ()
             name = 'Filters.chat_type.groups'
 
             def filter(self, message: Message) -> bool:
@@ -1294,6 +1408,7 @@ officedocument.wordprocessingml.document")``.
         groups = _Groups()
 
         class _Private(MessageFilter):
+            __slots__ = ()
             name = 'Filters.chat_type.private'
 
             def filter(self, message: Message) -> bool:
@@ -1321,6 +1436,15 @@ officedocument.wordprocessingml.document")``.
     """
 
     class _ChatUserBaseFilter(MessageFilter, ABC):
+        __slots__ = (
+            'chat_id_name',
+            'username_name',
+            'allow_empty',
+            '__lock',
+            '_chat_ids',
+            '_usernames',
+        )
+
         def __init__(
             self,
             chat_id: SLT[int] = None,
@@ -1497,6 +1621,8 @@ officedocument.wordprocessingml.document")``.
 
         """
 
+        __slots__ = ()
+
         def __init__(
             self,
             user_id: SLT[int] = None,
@@ -1596,6 +1722,8 @@ officedocument.wordprocessingml.document")``.
 
         """
 
+        __slots__ = ()
+
         def __init__(
             self,
             bot_id: SLT[int] = None,
@@ -1695,6 +1823,8 @@ officedocument.wordprocessingml.document")``.
 
         """
 
+        __slots__ = ()
+
         def get_chat_or_user(self, message: Message) -> Optional[Chat]:
             return message.chat
 
@@ -1786,6 +1916,8 @@ officedocument.wordprocessingml.document")``.
                 is specified in :attr:`chat_ids` and :attr:`usernames`.
         """
 
+        __slots__ = ()
+
         def get_chat_or_user(self, message: Message) -> Union[User, Chat, None]:
             return message.forward_from or message.forward_from_chat
 
@@ -1891,6 +2023,8 @@ officedocument.wordprocessingml.document")``.
 
         """
 
+        __slots__ = ()
+
         def get_chat_or_user(self, message: Message) -> Optional[Chat]:
             return message.sender_chat
 
@@ -1937,12 +2071,16 @@ officedocument.wordprocessingml.document")``.
             return super().remove_chat_ids(chat_id)
 
         class _SuperGroup(MessageFilter):
+            __slots__ = ()
+
             def filter(self, message: Message) -> bool:
                 if message.sender_chat:
                     return message.sender_chat.type == Chat.SUPERGROUP
                 return False
 
         class _Channel(MessageFilter):
+            __slots__ = ()
+
             def filter(self, message: Message) -> bool:
                 if message.sender_chat:
                     return message.sender_chat.type == Chat.CHANNEL
@@ -1952,6 +2090,7 @@ officedocument.wordprocessingml.document")``.
         channel = _Channel()
 
     class _Invoice(MessageFilter):
+        __slots__ = ()
         name = 'Filters.invoice'
 
         def filter(self, message: Message) -> bool:
@@ -1961,6 +2100,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain :class:`telegram.Invoice`."""
 
     class _SuccessfulPayment(MessageFilter):
+        __slots__ = ()
         name = 'Filters.successful_payment'
 
         def filter(self, message: Message) -> bool:
@@ -1970,6 +2110,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that confirm a :class:`telegram.SuccessfulPayment`."""
 
     class _PassportData(MessageFilter):
+        __slots__ = ()
         name = 'Filters.passport_data'
 
         def filter(self, message: Message) -> bool:
@@ -1979,6 +2120,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain a :class:`telegram.PassportData`"""
 
     class _Poll(MessageFilter):
+        __slots__ = ()
         name = 'Filters.poll'
 
         def filter(self, message: Message) -> bool:
@@ -1988,6 +2130,7 @@ officedocument.wordprocessingml.document")``.
     """Messages that contain a :class:`telegram.Poll`."""
 
     class _Dice(_DiceEmoji):
+        __slots__ = ()
         dice = _DiceEmoji('🎲', 'dice')
         darts = _DiceEmoji('🎯', 'darts')
         basketball = _DiceEmoji('🏀', 'basketball')
@@ -2051,6 +2194,8 @@ officedocument.wordprocessingml.document")``.
 
         """
 
+        __slots__ = ('lang',)
+
         def __init__(self, lang: SLT[str]):
             if isinstance(lang, str):
                 lang = cast(str, lang)
@@ -2068,6 +2213,8 @@ officedocument.wordprocessingml.document")``.
             )
 
     class _Attachment(MessageFilter):
+        __slots__ = ()
+
         name = 'Filters.attachment'
 
         def filter(self, message: Message) -> bool:
@@ -2080,9 +2227,11 @@ officedocument.wordprocessingml.document")``.
         .. versionadded:: 13.6"""
 
     class _UpdateType(UpdateFilter):
+        __slots__ = ()
         name = 'Filters.update'
 
         class _Message(UpdateFilter):
+            __slots__ = ()
             name = 'Filters.update.message'
 
             def filter(self, update: Update) -> bool:
@@ -2091,6 +2240,7 @@ officedocument.wordprocessingml.document")``.
         message = _Message()
 
         class _EditedMessage(UpdateFilter):
+            __slots__ = ()
             name = 'Filters.update.edited_message'
 
             def filter(self, update: Update) -> bool:
@@ -2099,6 +2249,7 @@ officedocument.wordprocessingml.document")``.
         edited_message = _EditedMessage()
 
         class _Messages(UpdateFilter):
+            __slots__ = ()
             name = 'Filters.update.messages'
 
             def filter(self, update: Update) -> bool:
@@ -2107,6 +2258,7 @@ officedocument.wordprocessingml.document")``.
         messages = _Messages()
 
         class _ChannelPost(UpdateFilter):
+            __slots__ = ()
             name = 'Filters.update.channel_post'
 
             def filter(self, update: Update) -> bool:
@@ -2115,6 +2267,7 @@ officedocument.wordprocessingml.document")``.
         channel_post = _ChannelPost()
 
         class _EditedChannelPost(UpdateFilter):
+            __slots__ = ()
             name = 'Filters.update.edited_channel_post'
 
             def filter(self, update: Update) -> bool:
@@ -2123,6 +2276,7 @@ officedocument.wordprocessingml.document")``.
         edited_channel_post = _EditedChannelPost()
 
         class _ChannelPosts(UpdateFilter):
+            __slots__ = ()
             name = 'Filters.update.channel_posts'
 
             def filter(self, update: Update) -> bool:

telegram/ext/handler.py

@@ -17,9 +17,11 @@
 # You should have received a copy of the GNU Lesser Public License
 # along with this program.  If not, see [http://www.gnu.org/licenses/].
 """This module contains the base class for handlers as used by the Dispatcher."""
-
 from abc import ABC, abstractmethod
 from typing import TYPE_CHECKING, Any, Callable, Dict, Optional, TypeVar, Union, Generic
+from sys import version_info as py_ver
+
+from telegram.utils.deprecate import set_new_attribute_deprecated
 
 from telegram import Update
 from telegram.ext.utils.promise import Promise
@@ -90,6 +92,27 @@ class Handler(Generic[UT], ABC):
 
     """
 
+    # Apparently Py 3.7 and below have '__dict__' in ABC
+    if py_ver < (3, 7):
+        __slots__ = (
+            'callback',
+            'pass_update_queue',
+            'pass_job_queue',
+            'pass_user_data',
+            'pass_chat_data',
+            'run_async',
+        )
+    else:
+        __slots__ = (
+            'callback',  # type: ignore[assignment]
+            'pass_update_queue',
+            'pass_job_queue',
+            'pass_user_data',
+            'pass_chat_data',
+            'run_async',
+            '__dict__',
+        )
+
     def __init__(
         self,
         callback: Callable[[UT, 'CallbackContext'], RT],
@@ -106,6 +129,17 @@ class Handler(Generic[UT], ABC):
         self.pass_chat_data = pass_chat_data
         self.run_async = run_async
 
+    def __setattr__(self, key: str, value: object) -> None:
+        # See comment on BaseFilter to know why this was done.
+        if key.startswith('__'):
+            key = f"_{self.__class__.__name__}{key}"
+        if issubclass(self.__class__, Handler) and not self.__class__.__module__.startswith(
+            'telegram.ext.'
+        ):
+            object.__setattr__(self, key, value)
+            return
+        set_new_attribute_deprecated(self, key, value)
+
     @abstractmethod
     def check_update(self, update: object) -> Optional[Union[bool, object]]:
         """

telegram/ext/inlinequeryhandler.py

@@ -129,6 +129,8 @@ class InlineQueryHandler(Handler[Update]):
 
     """
 
+    __slots__ = ('pattern', 'chat_types', 'pass_groups', 'pass_groupdict')
+
     def __init__(
         self,
         callback: Callable[[Update, 'CallbackContext'], RT],

telegram/ext/jobqueue.py

@@ -31,6 +31,7 @@ from apscheduler.job import Job as APSJob
 
 from telegram.ext.callbackcontext import CallbackContext
 from telegram.utils.types import JSONDict
+from telegram.utils.deprecate import set_new_attribute_deprecated
 
 if TYPE_CHECKING:
     from telegram import Bot
@@ -49,6 +50,8 @@ class JobQueue:
 
     """
 
+    __slots__ = ('_dispatcher', 'logger', 'scheduler', '__dict__')
+
     def __init__(self) -> None:
         self._dispatcher: 'Dispatcher' = None  # type: ignore[assignment]
         self.logger = logging.getLogger(self.__class__.__name__)
@@ -64,6 +67,9 @@ class JobQueue:
         logging.getLogger('apscheduler.executors.default').addFilter(aps_log_filter)
         self.scheduler.add_listener(self._dispatch_error, EVENT_JOB_ERROR)
 
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)
+
     def _build_args(self, job: 'Job') -> List[Union[CallbackContext, 'Bot', 'Job']]:
         if self._dispatcher.use_context:
             return [CallbackContext.from_job(job, self._dispatcher)]
@@ -542,6 +548,17 @@ class Job:
         job (:class:`apscheduler.job.Job`): Optional. The APS Job this job is a wrapper for.
     """
 
+    __slots__ = (
+        'callback',
+        'context',
+        'name',
+        'job_queue',
+        '_removed',
+        '_enabled',
+        'job',
+        '__dict__',
+    )
+
     def __init__(
         self,
         callback: Callable[['CallbackContext'], None],
@@ -561,6 +578,9 @@ class Job:
 
         self.job = cast(APSJob, job)  # skipcq: PTC-W0052
 
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)
+
     def run(self, dispatcher: 'Dispatcher') -> None:
         """Executes the callback function independently of the jobs schedule."""
         try:

telegram/ext/messagehandler.py

@@ -120,6 +120,8 @@ class MessageHandler(Handler[Update]):
 
     """
 
+    __slots__ = ('filters',)
+
     def __init__(
         self,
         filters: BaseFilter,

telegram/ext/messagequeue.py

@@ -40,6 +40,8 @@ curtime = time.perf_counter
 class DelayQueueError(RuntimeError):
     """Indicates processing errors."""
 
+    __slots__ = ()
+
 
 class DelayQueue(threading.Thread):
     """

telegram/ext/picklepersistence.py

@@ -73,6 +73,16 @@ class PicklePersistence(BasePersistence):
             Default is :obj:`False`.
     """
 
+    __slots__ = (
+        'filename',
+        'single_file',
+        'on_flush',
+        'user_data',
+        'chat_data',
+        'bot_data',
+        'conversations',
+    )
+
     def __init__(
         self,
         filename: str,

telegram/ext/pollanswerhandler.py

@@ -82,6 +82,8 @@ class PollAnswerHandler(Handler[Update]):
 
     """
 
+    __slots__ = ()
+
     def check_update(self, update: object) -> bool:
         """Determines whether an update should be passed to this handlers :attr:`callback`.
 

telegram/ext/pollhandler.py

@@ -82,6 +82,8 @@ class PollHandler(Handler[Update]):
 
     """
 
+    __slots__ = ()
+
     def check_update(self, update: object) -> bool:
         """Determines whether an update should be passed to this handlers :attr:`callback`.
 

telegram/ext/precheckoutqueryhandler.py

@@ -82,6 +82,8 @@ class PreCheckoutQueryHandler(Handler[Update]):
 
     """
 
+    __slots__ = ()
+
     def check_update(self, update: object) -> bool:
         """Determines whether an update should be passed to this handlers :attr:`callback`.
 

telegram/ext/regexhandler.py

@@ -108,6 +108,8 @@ class RegexHandler(MessageHandler):
 
     """
 
+    __slots__ = ('pass_groups', 'pass_groupdict')
+
     def __init__(
         self,
         pattern: Union[str, Pattern],

telegram/ext/shippingqueryhandler.py

@@ -81,6 +81,8 @@ class ShippingQueryHandler(Handler[Update]):
 
     """
 
+    __slots__ = ()
+
     def check_update(self, update: object) -> bool:
         """Determines whether an update should be passed to this handlers :attr:`callback`.
 

telegram/ext/stringcommandhandler.py

@@ -85,6 +85,8 @@ class StringCommandHandler(Handler[str]):
 
     """
 
+    __slots__ = ('command', 'pass_args')
+
     def __init__(
         self,
         command: str,

telegram/ext/stringregexhandler.py

@@ -91,6 +91,8 @@ class StringRegexHandler(Handler[str]):
 
     """
 
+    __slots__ = ('pass_groups', 'pass_groupdict', 'pattern')
+
     def __init__(
         self,
         pattern: Union[str, Pattern],

telegram/ext/typehandler.py

@@ -75,6 +75,8 @@ class TypeHandler(Handler[UT]):
 
     """
 
+    __slots__ = ('type', 'strict')
+
     def __init__(
         self,
         type: Type[UT],  # pylint: disable=W0622
@@ -90,8 +92,8 @@ class TypeHandler(Handler[UT]):
             pass_job_queue=pass_job_queue,
             run_async=run_async,
         )
-        self.type = type
+        self.type = type  # pylint: disable=E0237
-        self.strict = strict
+        self.strict = strict  # pylint: disable=E0237
 
     def check_update(self, update: object) -> bool:
         """Determines whether an update should be passed to this handlers :attr:`callback`.

telegram/ext/updater.py

@@ -30,7 +30,7 @@ from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Tuple, Un
 from telegram import Bot, TelegramError
 from telegram.error import InvalidToken, RetryAfter, TimedOut, Unauthorized
 from telegram.ext import Dispatcher, JobQueue
-from telegram.utils.deprecate import TelegramDeprecationWarning
+from telegram.utils.deprecate import TelegramDeprecationWarning, set_new_attribute_deprecated
 from telegram.utils.helpers import get_signal_name
 from telegram.utils.request import Request
 from telegram.ext.utils.webhookhandler import WebhookAppClass, WebhookServer
@@ -105,7 +105,24 @@ class Updater:
 
     """
 
-    _request = None
+    __slots__ = (
+        'persistence',
+        'dispatcher',
+        'user_sig_handler',
+        'bot',
+        'logger',
+        'update_queue',
+        'job_queue',
+        '__exception_event',
+        'last_update_id',
+        'running',
+        '_request',
+        'is_idle',
+        'httpd',
+        '__lock',
+        '__threads',
+        '__dict__',
+    )
 
     def __init__(
         self,
@@ -150,6 +167,7 @@ class Updater:
                 raise ValueError('`dispatcher` and `use_context` are mutually exclusive')
 
         self.logger = logging.getLogger(__name__)
+        self._request = None
 
         if dispatcher is None:
             con_pool_size = workers + 4
@@ -219,6 +237,14 @@ class Updater:
         self.__lock = Lock()
         self.__threads: List[Thread] = []
 
+    def __setattr__(self, key: str, value: object) -> None:
+        if key.startswith('__'):
+            key = f"_{self.__class__.__name__}{key}"
+        if issubclass(self.__class__, Updater) and self.__class__ is not Updater:
+            object.__setattr__(self, key, value)
+            return
+        set_new_attribute_deprecated(self, key, value)
+
     def _init_thread(self, target: Callable, name: str, *args: object, **kwargs: object) -> None:
         thr = Thread(
             target=self._thread_wrapper,

telegram/ext/utils/promise.py

@@ -22,6 +22,7 @@ import logging
 from threading import Event
 from typing import Callable, List, Optional, Tuple, TypeVar, Union
 
+from telegram.utils.deprecate import set_new_attribute_deprecated
 from telegram.utils.types import JSONDict
 
 RT = TypeVar('RT')
@@ -54,6 +55,19 @@ class Promise:
 
     """
 
+    __slots__ = (
+        'pooled_function',
+        'args',
+        'kwargs',
+        'update',
+        'error_handling',
+        'done',
+        '_done_callback',
+        '_result',
+        '_exception',
+        '__dict__',
+    )
+
     # TODO: Remove error_handling parameter once we drop the @run_async decorator
     def __init__(
         self,
@@ -73,6 +87,9 @@ class Promise:
         self._result: Optional[RT] = None
         self._exception: Optional[Exception] = None
 
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)
+
     def run(self) -> None:
         """Calls the :attr:`pooled_function` callable."""
         try:

telegram/ext/utils/webhookhandler.py

@@ -30,6 +30,7 @@ from tornado.httpserver import HTTPServer
 from tornado.ioloop import IOLoop
 
 from telegram import Update
+from telegram.utils.deprecate import set_new_attribute_deprecated
 from telegram.utils.types import JSONDict
 
 if TYPE_CHECKING:
@@ -42,6 +43,18 @@ except ImportError:
 
 
 class WebhookServer:
+    __slots__ = (
+        'http_server',
+        'listen',
+        'port',
+        'loop',
+        'logger',
+        'is_running',
+        'server_lock',
+        'shutdown_lock',
+        '__dict__',
+    )
+
     def __init__(
         self, listen: str, port: int, webhook_app: 'WebhookAppClass', ssl_ctx: SSLContext
     ):
@@ -54,6 +67,9 @@ class WebhookServer:
         self.server_lock = Lock()
         self.shutdown_lock = Lock()
 
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)
+
     def serve_forever(self, ready: Event = None) -> None:
         with self.server_lock:
             IOLoop().make_current()

telegram/files/animation.py

@@ -65,6 +65,20 @@ class Animation(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bot',
+        'width',
+        'file_id',
+        'file_size',
+        'file_name',
+        'thumb',
+        'duration',
+        'mime_type',
+        'height',
+        'file_unique_id',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         file_id: str,

telegram/files/audio.py

@@ -69,6 +69,20 @@ class Audio(TelegramObject):
 
     """
 
+    __slots__ = (
+        'file_id',
+        'bot',
+        'file_size',
+        'file_name',
+        'thumb',
+        'title',
+        'duration',
+        'performer',
+        'mime_type',
+        'file_unique_id',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         file_id: str,

telegram/files/chatphoto.py

@@ -65,6 +65,15 @@ class ChatPhoto(TelegramObject):
 
     """
 
+    __slots__ = (
+        'big_file_unique_id',
+        'bot',
+        'small_file_id',
+        'small_file_unique_id',
+        'big_file_id',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         small_file_id: str,

telegram/files/contact.py

@@ -46,6 +46,8 @@ class Contact(TelegramObject):
 
     """
 
+    __slots__ = ('vcard', 'user_id', 'first_name', 'last_name', 'phone_number', '_id_attrs')
+
     def __init__(
         self,
         phone_number: str,

telegram/files/document.py

@@ -60,6 +60,17 @@ class Document(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bot',
+        'file_id',
+        'file_size',
+        'file_name',
+        'thumb',
+        'mime_type',
+        'file_unique_id',
+        '_id_attrs',
+    )
+
     _id_keys = ('file_id',)
 
     def __init__(

telegram/files/file.py

@@ -67,6 +67,16 @@ class File(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bot',
+        'file_id',
+        'file_size',
+        'file_unique_id',
+        'file_path',
+        '_credentials',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         file_id: str,

telegram/files/inputfile.py

@@ -26,6 +26,8 @@ import os
 from typing import IO, Optional, Tuple, Union
 from uuid import uuid4
 
+from telegram.utils.deprecate import set_new_attribute_deprecated
+
 DEFAULT_MIME_TYPE = 'application/octet-stream'
 logger = logging.getLogger(__name__)
 
@@ -50,6 +52,8 @@ class InputFile:
 
     """
 
+    __slots__ = ('filename', 'attach', 'input_file_content', 'mimetype', '__dict__')
+
     def __init__(self, obj: Union[IO, bytes], filename: str = None, attach: bool = None):
         self.filename = None
         if isinstance(obj, bytes):
@@ -74,6 +78,9 @@ class InputFile:
         if not self.filename:
             self.filename = self.mimetype.replace('/', '.')
 
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)
+
     @property
     def field_tuple(self) -> Tuple[str, bytes, str]:  # skipcq: PY-D0003
         return self.filename, self.input_file_content, self.mimetype

telegram/files/inputmedia.py

@@ -43,6 +43,7 @@ class InputMedia(TelegramObject):
 
     """
 
+    __slots__ = ()
     caption_entities: Union[List[MessageEntity], Tuple[MessageEntity, ...], None] = None
 
     def to_dict(self) -> JSONDict:
@@ -113,6 +114,18 @@ class InputMediaAnimation(InputMedia):
 
     """
 
+    __slots__ = (
+        'caption_entities',
+        'width',
+        'media',
+        'thumb',
+        'caption',
+        'duration',
+        'parse_mode',
+        'height',
+        'type',
+    )
+
     def __init__(
         self,
         media: Union[FileInput, Animation],
@@ -185,6 +198,8 @@ class InputMediaPhoto(InputMedia):
 
     """
 
+    __slots__ = ('caption_entities', 'media', 'caption', 'parse_mode', 'type')
+
     def __init__(
         self,
         media: Union[FileInput, PhotoSize],
@@ -265,6 +280,19 @@ class InputMediaVideo(InputMedia):
 
     """
 
+    __slots__ = (
+        'caption_entities',
+        'width',
+        'media',
+        'thumb',
+        'supports_streaming',
+        'caption',
+        'duration',
+        'parse_mode',
+        'height',
+        'type',
+    )
+
     def __init__(
         self,
         media: Union[FileInput, Video],
@@ -364,6 +392,18 @@ class InputMediaAudio(InputMedia):
 
     """
 
+    __slots__ = (
+        'caption_entities',
+        'media',
+        'thumb',
+        'caption',
+        'title',
+        'duration',
+        'type',
+        'parse_mode',
+        'performer',
+    )
+
     def __init__(
         self,
         media: Union[FileInput, Audio],
@@ -452,6 +492,16 @@ class InputMediaDocument(InputMedia):
 
     """
 
+    __slots__ = (
+        'caption_entities',
+        'media',
+        'thumb',
+        'caption',
+        'parse_mode',
+        'type',
+        'disable_content_type_detection',
+    )
+
     def __init__(
         self,
         media: Union[FileInput, Document],

telegram/files/location.py

@@ -56,6 +56,16 @@ class Location(TelegramObject):
 
     """
 
+    __slots__ = (
+        'longitude',
+        'horizontal_accuracy',
+        'proximity_alert_radius',
+        'live_period',
+        'latitude',
+        'heading',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         longitude: float,

telegram/files/photosize.py

@@ -58,6 +58,8 @@ class PhotoSize(TelegramObject):
 
     """
 
+    __slots__ = ('bot', 'width', 'file_id', 'file_size', 'height', 'file_unique_id', '_id_attrs')
+
     def __init__(
         self,
         file_id: str,

telegram/files/sticker.py

@@ -73,6 +73,21 @@ class Sticker(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bot',
+        'width',
+        'file_id',
+        'is_animated',
+        'file_size',
+        'thumb',
+        'set_name',
+        'mask_position',
+        'height',
+        'file_unique_id',
+        'emoji',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         file_id: str,
@@ -160,6 +175,16 @@ class StickerSet(TelegramObject):
 
     """
 
+    __slots__ = (
+        'is_animated',
+        'contains_masks',
+        'thumb',
+        'title',
+        'stickers',
+        'name',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         name: str,
@@ -233,6 +258,8 @@ class MaskPosition(TelegramObject):
 
     """
 
+    __slots__ = ('point', 'scale', 'x_shift', 'y_shift', '_id_attrs')
+
     FOREHEAD: ClassVar[str] = constants.STICKER_FOREHEAD
     """:const:`telegram.constants.STICKER_FOREHEAD`"""
     EYES: ClassVar[str] = constants.STICKER_EYES

telegram/files/venue.py

@@ -60,6 +60,17 @@ class Venue(TelegramObject):
 
     """
 
+    __slots__ = (
+        'google_place_type',
+        'location',
+        'title',
+        'address',
+        'foursquare_type',
+        'foursquare_id',
+        'google_place_id',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         location: Location,

telegram/files/video.py

@@ -66,6 +66,20 @@ class Video(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bot',
+        'width',
+        'file_id',
+        'file_size',
+        'file_name',
+        'thumb',
+        'duration',
+        'mime_type',
+        'height',
+        'file_unique_id',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         file_id: str,

telegram/files/videonote.py

@@ -61,6 +61,17 @@ class VideoNote(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bot',
+        'length',
+        'file_id',
+        'file_size',
+        'thumb',
+        'duration',
+        'file_unique_id',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         file_id: str,

telegram/files/voice.py

@@ -58,6 +58,16 @@ class Voice(TelegramObject):
 
     """
 
+    __slots__ = (
+        'bot',
+        'file_id',
+        'file_size',
+        'duration',
+        'mime_type',
+        'file_unique_id',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         file_id: str,

telegram/forcereply.py

@@ -50,6 +50,8 @@ class ForceReply(ReplyMarkup):
 
     """
 
+    __slots__ = ('selective', 'force_reply', '_id_attrs')
+
     def __init__(self, force_reply: bool = True, selective: bool = False, **_kwargs: Any):
         # Required
         self.force_reply = bool(force_reply)

telegram/games/callbackgame.py

@@ -23,3 +23,5 @@ from telegram import TelegramObject
 
 class CallbackGame(TelegramObject):
     """A placeholder, currently holds no information. Use BotFather to set up your game."""
+
+    __slots__ = ()

telegram/games/game.py

@@ -67,6 +67,16 @@ class Game(TelegramObject):
 
     """
 
+    __slots__ = (
+        'title',
+        'photo',
+        'description',
+        'text_entities',
+        'text',
+        'animation',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         title: str,

telegram/games/gamehighscore.py

@@ -45,6 +45,8 @@ class GameHighScore(TelegramObject):
 
     """
 
+    __slots__ = ('position', 'user', 'score', '_id_attrs')
+
     def __init__(self, position: int, user: User, score: int):
         self.position = position
         self.user = user

telegram/inline/inlinekeyboardbutton.py

@@ -83,6 +83,18 @@ class InlineKeyboardButton(TelegramObject):
 
     """
 
+    __slots__ = (
+        'callback_game',
+        'url',
+        'switch_inline_query_current_chat',
+        'callback_data',
+        'pay',
+        'switch_inline_query',
+        'text',
+        '_id_attrs',
+        'login_url',
+    )
+
     def __init__(
         self,
         text: str,

telegram/inline/inlinekeyboardmarkup.py

@@ -45,6 +45,8 @@ class InlineKeyboardMarkup(ReplyMarkup):
 
     """
 
+    __slots__ = ('inline_keyboard', '_id_attrs')
+
     def __init__(self, inline_keyboard: List[List[InlineKeyboardButton]], **_kwargs: Any):
         # Required
         self.inline_keyboard = inline_keyboard

telegram/inline/inlinequery.py

@@ -71,6 +71,8 @@ class InlineQuery(TelegramObject):
 
     """
 
+    __slots__ = ('bot', 'location', 'chat_type', 'id', 'offset', 'from_user', 'query', '_id_attrs')
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresult.py

@@ -46,6 +46,8 @@ class InlineQueryResult(TelegramObject):
 
     """
 
+    __slots__ = ('type', 'id', '_id_attrs')
+
     def __init__(self, type: str, id: str, **_kwargs: Any):
         # Required
         self.type = str(type)

telegram/inline/inlinequeryresultarticle.py

@@ -63,6 +63,18 @@ class InlineQueryResultArticle(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'thumb_width',
+        'thumb_height',
+        'hide_url',
+        'url',
+        'title',
+        'description',
+        'input_message_content',
+        'thumb_url',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultaudio.py

@@ -74,6 +74,18 @@ class InlineQueryResultAudio(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'caption',
+        'title',
+        'parse_mode',
+        'audio_url',
+        'performer',
+        'input_message_content',
+        'audio_duration',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcachedaudio.py

@@ -68,6 +68,15 @@ class InlineQueryResultCachedAudio(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'caption',
+        'parse_mode',
+        'audio_file_id',
+        'input_message_content',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcacheddocument.py

@@ -75,6 +75,17 @@ class InlineQueryResultCachedDocument(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'document_file_id',
+        'caption',
+        'title',
+        'description',
+        'parse_mode',
+        'input_message_content',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcachedgif.py

@@ -73,6 +73,16 @@ class InlineQueryResultCachedGif(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'caption',
+        'title',
+        'input_message_content',
+        'parse_mode',
+        'gif_file_id',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcachedmpeg4gif.py

@@ -73,6 +73,16 @@ class InlineQueryResultCachedMpeg4Gif(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'mpeg4_file_id',
+        'caption',
+        'title',
+        'parse_mode',
+        'input_message_content',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcachedphoto.py

@@ -76,6 +76,17 @@ class InlineQueryResultCachedPhoto(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'caption',
+        'title',
+        'description',
+        'parse_mode',
+        'photo_file_id',
+        'input_message_content',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcachedsticker.py

@@ -52,6 +52,8 @@ class InlineQueryResultCachedSticker(InlineQueryResult):
 
     """
 
+    __slots__ = ('reply_markup', 'input_message_content', 'sticker_file_id')
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcachedvideo.py

@@ -75,6 +75,17 @@ class InlineQueryResultCachedVideo(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'caption',
+        'title',
+        'description',
+        'parse_mode',
+        'input_message_content',
+        'video_file_id',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcachedvoice.py

@@ -70,6 +70,16 @@ class InlineQueryResultCachedVoice(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'caption',
+        'title',
+        'parse_mode',
+        'voice_file_id',
+        'input_message_content',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultcontact.py

@@ -66,6 +66,18 @@ class InlineQueryResultContact(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'thumb_width',
+        'thumb_height',
+        'vcard',
+        'first_name',
+        'last_name',
+        'phone_number',
+        'input_message_content',
+        'thumb_url',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultdocument.py

@@ -85,6 +85,21 @@ class InlineQueryResultDocument(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'document_url',
+        'thumb_width',
+        'thumb_height',
+        'caption',
+        'title',
+        'description',
+        'parse_mode',
+        'mime_type',
+        'thumb_url',
+        'input_message_content',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultgame.py

@@ -45,6 +45,8 @@ class InlineQueryResultGame(InlineQueryResult):
 
     """
 
+    __slots__ = ('reply_markup', 'game_short_name')
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultgif.py

@@ -86,6 +86,21 @@ class InlineQueryResultGif(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'gif_height',
+        'thumb_mime_type',
+        'caption_entities',
+        'gif_width',
+        'title',
+        'caption',
+        'parse_mode',
+        'gif_duration',
+        'input_message_content',
+        'gif_url',
+        'thumb_url',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultlocation.py

@@ -79,6 +79,21 @@ class InlineQueryResultLocation(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'longitude',
+        'reply_markup',
+        'thumb_width',
+        'thumb_height',
+        'heading',
+        'title',
+        'live_period',
+        'proximity_alert_radius',
+        'input_message_content',
+        'latitude',
+        'horizontal_accuracy',
+        'thumb_url',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultmpeg4gif.py

@@ -85,6 +85,21 @@ class InlineQueryResultMpeg4Gif(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'thumb_mime_type',
+        'caption_entities',
+        'mpeg4_duration',
+        'mpeg4_width',
+        'title',
+        'caption',
+        'parse_mode',
+        'input_message_content',
+        'mpeg4_url',
+        'mpeg4_height',
+        'thumb_url',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultphoto.py

@@ -82,6 +82,20 @@ class InlineQueryResultPhoto(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'photo_url',
+        'reply_markup',
+        'caption_entities',
+        'photo_width',
+        'caption',
+        'title',
+        'description',
+        'parse_mode',
+        'input_message_content',
+        'photo_height',
+        'thumb_url',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultvenue.py

@@ -79,6 +79,22 @@ class InlineQueryResultVenue(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'longitude',
+        'reply_markup',
+        'google_place_type',
+        'thumb_width',
+        'thumb_height',
+        'title',
+        'address',
+        'foursquare_id',
+        'foursquare_type',
+        'google_place_id',
+        'input_message_content',
+        'latitude',
+        'thumb_url',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultvideo.py

@@ -92,6 +92,22 @@ class InlineQueryResultVideo(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'video_url',
+        'reply_markup',
+        'caption_entities',
+        'caption',
+        'title',
+        'description',
+        'video_duration',
+        'parse_mode',
+        'mime_type',
+        'input_message_content',
+        'video_height',
+        'video_width',
+        'thumb_url',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inlinequeryresultvoice.py

@@ -73,6 +73,17 @@ class InlineQueryResultVoice(InlineQueryResult):
 
     """
 
+    __slots__ = (
+        'reply_markup',
+        'caption_entities',
+        'voice_duration',
+        'caption',
+        'title',
+        'voice_url',
+        'parse_mode',
+        'input_message_content',
+    )
+
     def __init__(
         self,
         id: str,  # pylint: disable=W0622

telegram/inline/inputcontactmessagecontent.py

@@ -46,6 +46,8 @@ class InputContactMessageContent(InputMessageContent):
 
     """
 
+    __slots__ = ('vcard', 'first_name', 'last_name', 'phone_number', '_id_attrs')
+
     def __init__(
         self,
         phone_number: str,

telegram/inline/inputinvoicemessagecontent.py

@@ -123,6 +123,30 @@ class InputInvoiceMessageContent(InputMessageContent):
 
     """
 
+    __slots__ = (
+        'title',
+        'description',
+        'payload',
+        'provider_token',
+        'currency',
+        'prices',
+        'max_tip_amount',
+        'suggested_tip_amounts',
+        'provider_data',
+        'photo_url',
+        'photo_size',
+        'photo_width',
+        'photo_height',
+        'need_name',
+        'need_phone_number',
+        'need_email',
+        'need_shipping_address',
+        'send_phone_number_to_provider',
+        'send_email_to_provider',
+        'is_flexible',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         title: str,

telegram/inline/inputlocationmessagecontent.py

@@ -59,6 +59,8 @@ class InputLocationMessageContent(InputMessageContent):
 
     """
 
+    __slots__ = ('longitude', 'horizontal_accuracy', 'proximity_alert_radius', 'live_period',
+                 'latitude', 'heading', '_id_attrs')
     # fmt: on
 
     def __init__(

telegram/inline/inputmessagecontent.py

@@ -30,3 +30,5 @@ class InputMessageContent(TelegramObject):
     :class:`telegram.InputVenueMessageContent` for more details.
 
     """
+
+    __slots__ = ()

telegram/inline/inputtextmessagecontent.py

@@ -59,6 +59,8 @@ class InputTextMessageContent(InputMessageContent):
 
     """
 
+    __slots__ = ('disable_web_page_preview', 'parse_mode', 'entities', 'message_text', '_id_attrs')
+
     def __init__(
         self,
         message_text: str,

telegram/inline/inputvenuemessagecontent.py

@@ -60,6 +60,18 @@ class InputVenueMessageContent(InputMessageContent):
 
     """
 
+    __slots__ = (
+        'longitude',
+        'google_place_type',
+        'title',
+        'address',
+        'foursquare_id',
+        'foursquare_type',
+        'google_place_id',
+        'latitude',
+        '_id_attrs',
+    )
+
     def __init__(
         self,
         latitude: float,

telegram/keyboardbutton.py

@@ -58,6 +58,8 @@ class KeyboardButton(TelegramObject):
 
     """
 
+    __slots__ = ('request_location', 'request_contact', 'request_poll', 'text', '_id_attrs')
+
     def __init__(
         self,
         text: str,

telegram/keyboardbuttonpolltype.py

@@ -37,6 +37,8 @@ class KeyboardButtonPollType(TelegramObject):
             create a poll of any type.
     """
 
+    __slots__ = ('type', '_id_attrs')
+
     def __init__(self, type: str = None, **_kwargs: Any):  # pylint: disable=W0622
         self.type = type
 

telegram/loginurl.py

@@ -69,6 +69,8 @@ class LoginUrl(TelegramObject):
 
     """
 
+    __slots__ = ('bot_username', 'request_write_access', 'url', 'forward_text', '_id_attrs')
+
     def __init__(
         self,
         url: str,

telegram/message.py

@@ -77,8 +77,6 @@ if TYPE_CHECKING:
         LabeledPrice,
     )
 
-_UNDEFINED = object()
-
 
 class Message(TelegramObject):
     # fmt: off
@@ -333,8 +331,67 @@ class Message(TelegramObject):
     """
 
     # fmt: on
-
+    __slots__ = (
-    _effective_attachment = _UNDEFINED
+        'reply_markup',
+        'audio',
+        'contact',
+        'migrate_to_chat_id',
+        'forward_signature',
+        'chat',
+        'successful_payment',
+        'game',
+        'text',
+        'forward_sender_name',
+        'document',
+        'new_chat_title',
+        'forward_date',
+        'group_chat_created',
+        'media_group_id',
+        'caption',
+        'video',
+        'bot',
+        'entities',
+        'via_bot',
+        'new_chat_members',
+        'connected_website',
+        'animation',
+        'migrate_from_chat_id',
+        'forward_from',
+        'sticker',
+        'location',
+        'venue',
+        'edit_date',
+        'reply_to_message',
+        'passport_data',
+        'pinned_message',
+        'forward_from_chat',
+        'new_chat_photo',
+        'message_id',
+        'delete_chat_photo',
+        'from_user',
+        'author_signature',
+        'proximity_alert_triggered',
+        'sender_chat',
+        'dice',
+        'forward_from_message_id',
+        'caption_entities',
+        'voice',
+        'date',
+        'supergroup_chat_created',
+        'poll',
+        'left_chat_member',
+        'photo',
+        'channel_chat_created',
+        'invoice',
+        'video_note',
+        '_effective_attachment',
+        'message_auto_delete_timer_changed',
+        'voice_chat_ended',
+        'voice_chat_participants_invited',
+        'voice_chat_started',
+        'voice_chat_scheduled',
+        '_id_attrs',
+    )
 
     ATTACHMENT_TYPES: ClassVar[List[str]] = [
         'audio',
@@ -497,6 +554,8 @@ class Message(TelegramObject):
         self.reply_markup = reply_markup
         self.bot = bot
 
+        self._effective_attachment = DEFAULT_NONE
+
         self._id_attrs = (self.message_id, self.chat)
 
     @property
@@ -613,7 +672,7 @@ class Message(TelegramObject):
             :obj:`None` if no attachment was sent.
 
         """
-        if self._effective_attachment is not _UNDEFINED:
+        if self._effective_attachment is not DEFAULT_NONE:
             return self._effective_attachment  # type: ignore
 
         for i in Message.ATTACHMENT_TYPES:
@@ -626,10 +685,7 @@ class Message(TelegramObject):
         return self._effective_attachment  # type: ignore
 
     def __getitem__(self, item: str) -> Any:  # pylint: disable=R1710
-        if item in self.__dict__.keys():
+        return self.chat.id if item == 'chat_id' else super().__getitem__(item)
-            return self.__dict__[item]
-        if item == 'chat_id':
-            return self.chat.id
 
     def to_dict(self) -> JSONDict:
         """See :meth:`telegram.TelegramObject.to_dict`."""

telegram/messageautodeletetimerchanged.py

@@ -44,6 +44,8 @@ class MessageAutoDeleteTimerChanged(TelegramObject):
 
     """
 
+    __slots__ = ('message_auto_delete_time', '_id_attrs')
+
     def __init__(
         self,
         message_auto_delete_time: int,

telegram/messageentity.py

@@ -59,6 +59,8 @@ class MessageEntity(TelegramObject):
 
     """
 
+    __slots__ = ('length', 'url', 'user', 'type', 'language', 'offset', '_id_attrs')
+
     def __init__(
         self,
         type: str,  # pylint: disable=W0622

telegram/messageid.py

@@ -32,6 +32,8 @@ class MessageId(TelegramObject):
         message_id (:obj:`int`): Unique message identifier
     """
 
+    __slots__ = ('message_id', '_id_attrs')
+
     def __init__(self, message_id: int, **_kwargs: Any):
         self.message_id = int(message_id)
 

telegram/parsemode.py

@@ -21,11 +21,14 @@
 from typing import ClassVar
 
 from telegram import constants
+from telegram.utils.deprecate import set_new_attribute_deprecated
 
 
 class ParseMode:
     """This object represents a Telegram Message Parse Modes."""
 
+    __slots__ = ('__dict__',)
+
     MARKDOWN: ClassVar[str] = constants.PARSEMODE_MARKDOWN
     """:const:`telegram.constants.PARSEMODE_MARKDOWN`\n
 
@@ -37,3 +40,6 @@ class ParseMode:
     """:const:`telegram.constants.PARSEMODE_MARKDOWN_V2`"""
     HTML: ClassVar[str] = constants.PARSEMODE_HTML
     """:const:`telegram.constants.PARSEMODE_HTML`"""
+
+    def __setattr__(self, key: str, value: object) -> None:
+        set_new_attribute_deprecated(self, key, value)

telegram/passport/credentials.py

@@ -51,6 +51,8 @@ if TYPE_CHECKING:
 class TelegramDecryptionError(TelegramError):
     """Something went wrong with decryption."""
 
+    __slots__ = ('_msg',)
+
     def __init__(self, message: Union[str, Exception]):
         super().__init__(f"TelegramDecryptionError: {message}")
         self._msg = str(message)
@@ -143,6 +145,16 @@ class EncryptedCredentials(TelegramObject):
 
     """
 
+    __slots__ = (
+        'hash',
+        'secret',
+        'bot',
+        'data',
+        '_id_attrs',
+        '_decrypted_secret',
+        '_decrypted_data',
+    )
+
     def __init__(self, data: str, hash: str, secret: str, bot: 'Bot' = None, **_kwargs: Any):
         # Required
         self.data = data
@@ -212,6 +224,8 @@ class Credentials(TelegramObject):
         nonce (:obj:`str`): Bot-specified nonce
     """
 
+    __slots__ = ('bot', 'nonce', 'secure_data')
+
     def __init__(self, secure_data: 'SecureData', nonce: str, bot: 'Bot' = None, **_kwargs: Any):
         # Required
         self.secure_data = secure_data
@@ -260,6 +274,21 @@ class SecureData(TelegramObject):
             temporary registration.
     """
 
+    __slots__ = (
+        'bot',
+        'utility_bill',
+        'personal_details',
+        'temporary_registration',
+        'address',
+        'driver_license',
+        'rental_agreement',
+        'internal_passport',
+        'identity_card',
+        'bank_statement',
+        'passport',
+        'passport_registration',
+    )
+
     def __init__(
         self,
         personal_details: 'SecureValue' = None,
@@ -345,6 +374,8 @@ class SecureValue(TelegramObject):
 
     """
 
+    __slots__ = ('data', 'front_side', 'reverse_side', 'selfie', 'files', 'translation', 'bot')
+
     def __init__(
         self,
         data: 'DataCredentials' = None,
@@ -395,6 +426,8 @@ class SecureValue(TelegramObject):
 class _CredentialsBase(TelegramObject):
     """Base class for DataCredentials and FileCredentials."""
 
+    __slots__ = ('hash', 'secret', 'file_hash', 'data_hash', 'bot')
+
     def __init__(self, hash: str, secret: str, bot: 'Bot' = None, **_kwargs: Any):
         self.hash = hash
         self.secret = secret
@@ -420,6 +453,8 @@ class DataCredentials(_CredentialsBase):
         secret (:obj:`str`): Secret of encrypted data
     """
 
+    __slots__ = ()
+
     def __init__(self, data_hash: str, secret: str, **_kwargs: Any):
         super().__init__(data_hash, secret, **_kwargs)
 
@@ -447,6 +482,8 @@ class FileCredentials(_CredentialsBase):
         secret (:obj:`str`): Secret of encrypted file
     """
 
+    __slots__ = ()
+
     def __init__(self, file_hash: str, secret: str, **_kwargs: Any):
         super().__init__(file_hash, secret, **_kwargs)