Don't automatically start the client via async-with

readthedocs/misc/v2-migration-guide.rst

@@ -178,6 +178,38 @@ The following modules have been moved inside ``_misc``:
 // TODO review telethon/__init__.py isn't exposing more than it should
 
 
+Using the client in a context-manager no longer calls start automatically
+-------------------------------------------------------------------------
+
+
+The following code no longer automatically calls ``client.start()``:
+
+.. code-block:: python
+
+    async with TelegramClient(...) as client:
+        ...
+
+    # or
+
+    async with client:
+        ...
+
+
+This means the context-manager will only call ``client.connect()`` and ``client.disconnect()``.
+The rationale for this change is that it could be strange for this to ask for the login code if
+the session ever was invalid. If you want the old behaviour, you now need to be explicit:
+
+
+.. code-block:: python
+
+    async with TelegramClient(...).start() as client:
+        ...  #                    ++++++++
+
+
+Note that you do not need to ``await`` the call to ``.start()`` if you are going to use the result
+in a context-manager (but it's okay if you put the ``await``).
+
+
 Support for bot-API style file_id has been removed
 --------------------------------------------------
 

telethon/_client/auth.py

@@ -4,6 +4,7 @@ import os
 import sys
 import typing
 import warnings
+import functools
 
 from .._misc import utils, helpers, password as pwd_mod
 from .. import errors, _tl
@@ -13,7 +14,23 @@ if typing.TYPE_CHECKING:
     from .telegramclient import TelegramClient
 
 
-async def start(
+class StartingClient:
+    def __init__(self, client, start_fn):
+        self.client = client
+        self.start_fn = start_fn
+
+    async def __aenter__(self):
+        await self.start_fn()
+        return self.client
+
+    async def __aexit__(self, *args):
+        await self.client.__aexit__(*args)
+
+    def __await__(self):
+        return self.__aenter__().__await__()
+
+
+def start(
         self: 'TelegramClient',
         phone: typing.Callable[[], str] = lambda: input('Please enter your phone (or bot token): '),
         password: typing.Callable[[], str] = lambda: getpass.getpass('Please enter your password: '),
@@ -40,7 +57,7 @@ async def start(
         raise ValueError('Both a phone and a bot token provided, '
                             'must only provide one of either')
 
-    return await _start(
+    return StartingClient(self, functools.partial(_start,
         self=self,
         phone=phone,
         password=password,
@@ -50,7 +67,7 @@ async def start(
         first_name=first_name,
         last_name=last_name,
         max_attempts=max_attempts
-    )
+    ))
 
 async def _start(
         self: 'TelegramClient', phone, password, bot_token, force_sms,

telethon/_client/telegramclient.py

@@ -281,7 +281,7 @@ class TelegramClient:
 
     # region Auth
 
-    async def start(
+    def start(
             self: 'TelegramClient',
             phone: typing.Callable[[], str] = lambda: input('Please enter your phone (or bot token): '),
             password: typing.Callable[[], str] = lambda: getpass.getpass('Please enter your password: '),
@@ -304,9 +304,8 @@ class TelegramClient:
         will be banned otherwise.** See https://telegram.org/tos
         and https://core.telegram.org/api/terms.
 
-        If the event loop is already running, this method returns a
-        coroutine that you should await on your own code; otherwise
-        the loop is ran until said coroutine completes.
+        Even though this method is not marked as ``async``, you still need to
+        ``await`` its result for it to do anything useful.
 
         Arguments
             phone (`str` | `int` | `callable`):
@@ -363,11 +362,11 @@ class TelegramClient:
                 # Please enter your password: *******
                 # (You are now logged in)
 
-                # Starting using a context manager (this calls start()):
-                with client:
+                # Starting using a context manager (note the lack of await):
+                async with client.start():
                     pass
         """
-        return await auth.start(**locals())
+        return auth.start(**locals())
 
     async def sign_in(
             self: 'TelegramClient',
@@ -621,7 +620,8 @@ class TelegramClient:
         return await auth.edit_2fa(**locals())
 
     async def __aenter__(self):
-        return await self.start()
+        await self.connect()
+        return self
 
     async def __aexit__(self, *args):
         await self.disconnect()