Change stderr prints to use the logging module instead

docs/api.rst

@@ -195,7 +195,7 @@ overriding the specific events. For example: ::
 
 
 If an event handler raises an exception, :func:`on_error` will be called
-to handle it, which defaults to print a traceback and ignoring the exception.
+to handle it, which defaults to logging the traceback and ignoring the exception.
 
 .. warning::
 
@@ -350,7 +350,7 @@ Debug
 .. function:: on_error(event, *args, **kwargs)
 
     Usually when an event raises an uncaught exception, a traceback is
-    printed to stderr and the exception is ignored. If you want to
+    logged to stderr and the exception is ignored. If you want to
     change this behaviour and handle the exception for whatever reason
     yourself, this event can be overridden. Which, when done, will
     suppress the default action of printing the traceback.
@@ -358,11 +358,6 @@ Debug
     The information of the exception raised and the exception itself can
     be retrieved with a standard call to :func:`sys.exc_info`.
 
-    If you want exception to propagate out of the :class:`Client` class
-    you can define an ``on_error`` handler consisting of a single empty
-    :ref:`raise statement <py:raise>`. Exceptions raised by ``on_error`` will not be
-    handled in any way by :class:`Client`.
-
     .. note::
 
         ``on_error`` will only be dispatched to :meth:`Client.event`.
@@ -371,6 +366,10 @@ Debug
         :ref:`ext_commands_api_bot` listeners such as
         :meth:`~ext.commands.Bot.listen` or :meth:`~ext.commands.Cog.listener`.
 
+    .. versionchanged:: 2.0
+
+        The traceback is now logged rather than printed.
+
     :param event: The name of the event that raised the exception.
     :type event: :class:`str`
 

docs/migrating.rst

@@ -933,6 +933,17 @@ The following methods have been changed:
 - :meth:`Webhook.send`
 - :meth:`abc.GuildChannel.set_permissions`
 
+Logging Changes
+----------------
+
+The library now provides a default logging configuration if using :meth:`Client.run`. To disable it, pass ``None`` to the ``log_handler`` keyword parameter. Since the library now provides a default logging configuration, certain methods were changed to no longer print to :data:`sys.stderr` but use the logger instead:
+
+- :meth:`Client.on_error`
+- :meth:`discord.ext.tasks.Loop.error`
+- :meth:`discord.ext.commands.Bot.on_command_error`
+
+For more information, check :doc:`logging`.
+
 Removal of ``StoreChannel``
 -----------------------------