Attempt to remove backcall.

This was meant to allow this API to evolve, but I have the impression
was not use much.

This will reduce our dependencies and reliance on older packages.

IPython/core/events.py

@@ -1,166 +1,155 b''
 """Infrastructure for registering and firing callbacks on application events.
 
 Unlike :mod:`IPython.core.hooks`, which lets end users set single functions to
 be called at specific times, or a collection of alternative methods to try,
 callbacks are designed to be used by extension authors. A number of callbacks
 can be registered for the same event without needing to be aware of one another.
 
 The functions defined in this module are no-ops indicating the names of available
 events and the arguments which will be passed to them.
 
 .. note::
 
    This API is experimental in IPython 2.0, and may be revised in future versions.
 """
 
-from backcall import callback_prototype
-
 
 class EventManager(object):
     """Manage a collection of events and a sequence of callbacks for each.
     
     This is attached to :class:`~IPython.core.interactiveshell.InteractiveShell`
     instances as an ``events`` attribute.
     
     .. note::
 
        This API is experimental in IPython 2.0, and may be revised in future versions.
     """
 
     def __init__(self, shell, available_events, print_on_error=True):
         """Initialise the :class:`CallbackManager`.
 
         Parameters
         ----------
         shell
             The :class:`~IPython.core.interactiveshell.InteractiveShell` instance
         available_events
             An iterable of names for callback events.
         print_on_error:
             A boolean flag to set whether the EventManager will print a warning which a event errors.
         """
         self.shell = shell
         self.callbacks = {n:[] for n in available_events}
         self.print_on_error = print_on_error
     
     def register(self, event, function):
         """Register a new event callback.
 
         Parameters
         ----------
         event : str
             The event for which to register this callback.
         function : callable
             A function to be called on the given event. It should take the same
             parameters as the appropriate callback prototype.
 
         Raises
         ------
         TypeError
             If ``function`` is not callable.
         KeyError
             If ``event`` is not one of the known events.
         """
         if not callable(function):
             raise TypeError('Need a callable, got %r' % function)
-        callback_proto = available_events.get(event)
         if function not in self.callbacks[event]:
-            self.callbacks[event].append(callback_proto.adapt(function))
+            self.callbacks[event].append(function)
     
     def unregister(self, event, function):
         """Remove a callback from the given event."""
         if function in self.callbacks[event]:
             return self.callbacks[event].remove(function)
 
-        # Remove callback in case ``function`` was adapted by `backcall`.
-        for callback in self.callbacks[event]:
-            try:
-                if callback.__wrapped__ is function:
-                    return self.callbacks[event].remove(callback)
-            except AttributeError:
-                pass
-
         raise ValueError('Function {!r} is not registered as a {} callback'.format(function, event))
 
     def trigger(self, event, *args, **kwargs):
         """Call callbacks for ``event``.
 
         Any additional arguments are passed to all callbacks registered for this
         event. Exceptions raised by callbacks are caught, and a message printed.
         """
         for func in self.callbacks[event][:]:
             try:
                 func(*args, **kwargs)
             except (Exception, KeyboardInterrupt):
                 if self.print_on_error:
                     print("Error in callback {} (for {}):".format(func, event))
                 self.shell.showtraceback()
 
 # event_name -> prototype mapping
 available_events = {}
 
 def _define_event(callback_function):
     callback_proto = callback_prototype(callback_function)
     available_events[callback_function.__name__] = callback_proto
     return callback_proto
 
 # ------------------------------------------------------------------------------
 # Callback prototypes
 #
 # No-op functions which describe the names of available events and the
 # signatures of callbacks for those events.
 # ------------------------------------------------------------------------------
 
 @_define_event
 def pre_execute():
     """Fires before code is executed in response to user/frontend action.
 
     This includes comm and widget messages and silent execution, as well as user
     code cells.
     """
     pass
 
 @_define_event
 def pre_run_cell(info):
     """Fires before user-entered code runs.
 
     Parameters
     ----------
     info : :class:`~IPython.core.interactiveshell.ExecutionInfo`
         An object containing information used for the code execution.
     """
     pass
 
 @_define_event
 def post_execute():
     """Fires after code is executed in response to user/frontend action.
 
     This includes comm and widget messages and silent execution, as well as user
     code cells.
     """
     pass
 
 @_define_event
 def post_run_cell(result):
     """Fires after user-entered code runs.
 
     Parameters
     ----------
     result : :class:`~IPython.core.interactiveshell.ExecutionResult`
         The object which will be returned as the execution result.
     """
     pass
 
 @_define_event
 def shell_initialized(ip):
     """Fires after initialisation of :class:`~IPython.core.interactiveshell.InteractiveShell`.
 
     This is before extensions and startup scripts are loaded, so it can only be
     set by subclassing.
 
     Parameters
     ----------
     ip : :class:`~IPython.core.interactiveshell.InteractiveShell`
         The newly initialised shell.
     """
     pass

setup.cfg

@@ -1,118 +1,117 b''
 [metadata]
 name = ipython
 version = attr: IPython.core.release.__version__
 url = https://ipython.org
 description = IPython: Productive Interactive Computing
 long_description_content_type = text/x-rst
 long_description = file: long_description.rst
 license_file = LICENSE
 project_urls =
     Documentation = https://ipython.readthedocs.io/
     Funding = https://numfocus.org/
     Source = https://github.com/ipython/ipython
     Tracker = https://github.com/ipython/ipython/issues
 keywords = Interactive, Interpreter, Shell, Embedding
 platforms = Linux, Mac OSX, Windows
 classifiers =
     Framework :: IPython
     Framework :: Jupyter
     Intended Audience :: Developers
     Intended Audience :: Science/Research
     License :: OSI Approved :: BSD License
     Programming Language :: Python
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3 :: Only
     Topic :: System :: Shells
 
 [options]
 packages = find:
 python_requires = >=3.9
 zip_safe = False
 install_requires =
     appnope; sys_platform == "darwin"
-    backcall
     colorama; sys_platform == "win32"
     decorator
     exceptiongroup; python_version<'3.11'
     jedi>=0.16
     matplotlib-inline
     pexpect>4.3; sys_platform != "win32"
     pickleshare
     prompt_toolkit>=3.0.30,<3.1.0,!=3.0.37
     pygments>=2.4.0
     stack_data
     traitlets>=5
     typing_extensions ; python_version<'3.10'
 
 [options.extras_require]
 black =
     black
 doc =
     ipykernel
     setuptools>=18.5
     sphinx>=1.3
     sphinx-rtd-theme
     docrepr
     matplotlib
     stack_data
     pytest<7
     typing_extensions
     exceptiongroup
     %(test)s
 kernel =
     ipykernel
 nbconvert =
     nbconvert
 nbformat =
     nbformat
 notebook =
     ipywidgets
     notebook
 parallel =
     ipyparallel
 qtconsole =
     qtconsole
 terminal =
 test =
     pytest<7.1
     pytest-asyncio
     testpath
 test_extra =
     %(test)s
     curio
     matplotlib!=3.2.0
     nbformat
     numpy>=1.22
     pandas
     trio
 all =
     %(black)s
     %(doc)s
     %(kernel)s
     %(nbconvert)s
     %(nbformat)s
     %(notebook)s
     %(parallel)s
     %(qtconsole)s
     %(terminal)s
     %(test_extra)s
     %(test)s
 
 [options.packages.find]
 exclude =
     setupext
 
 [options.package_data]
 IPython = py.typed
 IPython.core = profile/README*
 IPython.core.tests = *.png, *.jpg, daft_extension/*.py
 IPython.lib.tests = *.wav
 IPython.testing.plugin = *.txt
 
 [velin]
 ignore_patterns =
    IPython/core/tests
    IPython/testing
 
 [tool.black]
 exclude = 'timing\.py'