bpo-36492: Deprecate passing some arguments as keyword arguments. (pythonGH-12637)

Deprecated passing the following arguments as keyword arguments: - "func" in functools.partialmethod(), weakref.finalize(), profile.Profile.runcall(), cProfile.Profile.runcall(), bdb.Bdb.runcall(), trace.Trace.runfunc() and curses.wrapper(). - "function" in unittest.addModuleCleanup() and unittest.TestCase.addCleanup(). - "fn" in the submit() method of concurrent.futures.ThreadPoolExecutor and concurrent.futures.ProcessPoolExecutor. - "callback" in contextlib.ExitStack.callback(), contextlib.AsyncExitStack.callback() and contextlib.AsyncExitStack.push_async_callback(). - "c" and "typeid" in the create() method of multiprocessing.managers.Server and multiprocessing.managers.SharedMemoryServer. - "obj" in weakref.finalize(). Also allowed to pass arbitrary keyword arguments (even "self" and "func") if the above arguments are passed as positional argument.

Author: serhiy-storchaka

Doc/whatsnew/3.8.rst

@@ -594,6 +594,29 @@ Deprecated
  version they will be errors.
  (Contributed by Serhiy Storchaka in :issue:`36048`.)
 
+* Deprecated passing the following arguments as keyword arguments:
+
+ - *func* in :func:`functools.partialmethod`, :func:`weakref.finalize`,
+ :meth:`profile.Profile.runcall`, :meth:`cProfile.Profile.runcall`,
+ :meth:`bdb.Bdb.runcall`, :meth:`trace.Trace.runfunc` and
+ :func:`curses.wrapper`.
+ - *function* in :func:`unittest.addModuleCleanup` and
+ :meth:`unittest.TestCase.addCleanup`.
+ - *fn* in the :meth:`~concurrent.futures.Executor.submit` method of
+ :class:`concurrent.futures.ThreadPoolExecutor` and
+ :class:`concurrent.futures.ProcessPoolExecutor`.
+ - *callback* in :meth:`contextlib.ExitStack.callback`,
+ :meth:`contextlib.AsyncExitStack.callback` and
+ :meth:`contextlib.AsyncExitStack.push_async_callback`.
+ - *c* and *typeid* in the :meth:`~multiprocessing.managers.Server.create`
+ method of :class:`multiprocessing.managers.Server` and
+ :class:`multiprocessing.managers.SharedMemoryServer`.
+ - *obj* in :func:`weakref.finalize`.
+
+ In future releases of Python they will be :ref:`positional-only
+ <positional-only_parameter>`.
+ (Contributed by Serhiy Storchaka in :issue:`36492`.)
+
 
 API and Feature Removals
 ========================

Lib/bdb.py

@@ -618,11 +618,26 @@ def runctx(self, cmd, globals, locals):
 
  # This method is more useful to debug a single function call.
 
- def runcall(self, func, *args, **kwds):
+ def runcall(*args, **kwds):
  """Debug a single function call.
 
  Return the result of the function call.
  """
+ if len(args) >= 2:
+ self, func, *args = args
+ elif not args:
+ raise TypeError("descriptor 'runcall' of 'Bdb' object "
+ "needs an argument")
+ elif 'func' in kwds:
+ func = kwds.pop('func')
+ self, *args = args
+ import warnings
+ warnings.warn("Passing 'func' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError('runcall expected at least 1 positional argument, '
+ 'got %d' % (len(args)-1))
+
  self.reset()
  sys.settrace(self.trace_dispatch)
  res = None

Lib/cProfile.py

@@ -103,7 +103,22 @@ def runctx(self, cmd, globals, locals):
  return self
 
  # This method is more useful to profile a single function call.
- def runcall(self, func, *args, **kw):
+ def runcall(*args, **kw):
+ if len(args) >= 2:
+ self, func, *args = args
+ elif not args:
+ raise TypeError("descriptor 'runcall' of 'Profile' object "
+ "needs an argument")
+ elif 'func' in kw:
+ func = kw.pop('func')
+ self, *args = args
+ import warnings
+ warnings.warn("Passing 'func' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError('runcall expected at least 1 positional argument, '
+ 'got %d' % (len(args)-1))
+
  self.enable()
  try:
  return func(*args, **kw)

Lib/concurrent/futures/_base.py

@@ -544,7 +544,7 @@ def set_exception(self, exception):
 class Executor(object):
  """This is an abstract base class for concrete asynchronous executors."""
 
- def submit(self, fn, *args, **kwargs):
+ def submit(*args, **kwargs):
  """Submits a callable to be executed with the given arguments.
 
  Schedules the callable to be executed as fn(*args, **kwargs) and returns
@@ -553,6 +553,19 @@ def submit(self, fn, *args, **kwargs):
  Returns:
  A Future representing the given call.
  """
+ if len(args) >= 2:
+ pass
+ elif not args:
+ raise TypeError("descriptor 'submit' of 'Executor' object "
+ "needs an argument")
+ elif 'fn' in kwargs:
+ import warnings
+ warnings.warn("Passing 'fn' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError('submit expected at least 1 positional argument, '
+ 'got %d' % (len(args)-1))
+
  raise NotImplementedError()
 
  def map(self, fn, *iterables, timeout=None, chunksize=1):

Lib/concurrent/futures/process.py

@@ -594,7 +594,22 @@ def _adjust_process_count(self):
  p.start()
  self._processes[p.pid] = p
 
- def submit(self, fn, *args, **kwargs):
+ def submit(*args, **kwargs):
+ if len(args) >= 2:
+ self, fn, *args = args
+ elif not args:
+ raise TypeError("descriptor 'submit' of 'ProcessPoolExecutor' object "
+ "needs an argument")
+ elif 'fn' in kwargs:
+ fn = kwargs.pop('fn')
+ self, *args = args
+ import warnings
+ warnings.warn("Passing 'fn' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError('submit expected at least 1 positional argument, '
+ 'got %d' % (len(args)-1))
+
  with self._shutdown_lock:
  if self._broken:
  raise BrokenProcessPool(self._broken)

Lib/concurrent/futures/thread.py

@@ -142,7 +142,22 @@ def __init__(self, max_workers=None, thread_name_prefix='',
  self._initializer = initializer
  self._initargs = initargs
 
- def submit(self, fn, *args, **kwargs):
+ def submit(*args, **kwargs):
+ if len(args) >= 2:
+ self, fn, *args = args
+ elif not args:
+ raise TypeError("descriptor 'submit' of 'ThreadPoolExecutor' object "
+ "needs an argument")
+ elif 'fn' in kwargs:
+ fn = kwargs.pop('fn')
+ self, *args = args
+ import warnings
+ warnings.warn("Passing 'fn' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError('submit expected at least 1 positional argument, '
+ 'got %d' % (len(args)-1))
+
  with self._shutdown_lock:
  if self._broken:
  raise BrokenThreadPool(self._broken)

Lib/contextlib.py

@@ -377,7 +377,8 @@ def _create_exit_wrapper(cm, cm_exit):
  return MethodType(cm_exit, cm)
 
  @staticmethod
- def _create_cb_wrapper(callback, *args, **kwds):
+ def _create_cb_wrapper(*args, **kwds):
+ callback, *args = args
  def _exit_wrapper(exc_type, exc, tb):
  callback(*args, **kwds)
  return _exit_wrapper
@@ -426,11 +427,26 @@ def enter_context(self, cm):
  self._push_cm_exit(cm, _exit)
  return result
 
- def callback(self, callback, *args, **kwds):
+ def callback(*args, **kwds):
  """Registers an arbitrary callback and arguments.
 
  Cannot suppress exceptions.
  """
+ if len(args) >= 2:
+ self, callback, *args = args
+ elif not args:
+ raise TypeError("descriptor 'callback' of '_BaseExitStack' object "
+ "needs an argument")
+ elif 'callback' in kwds:
+ callback = kwds.pop('callback')
+ self, *args = args
+ import warnings
+ warnings.warn("Passing 'callback' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError('callback expected at least 1 positional argument, '
+ 'got %d' % (len(args)-1))
+
  _exit_wrapper = self._create_cb_wrapper(callback, *args, **kwds)
 
  # We changed the signature, so using @wraps is not appropriate, but
@@ -536,7 +552,8 @@ def _create_async_exit_wrapper(cm, cm_exit):
  return MethodType(cm_exit, cm)
 
  @staticmethod
- def _create_async_cb_wrapper(callback, *args, **kwds):
+ def _create_async_cb_wrapper(*args, **kwds):
+ callback, *args = args
  async def _exit_wrapper(exc_type, exc, tb):
  await callback(*args, **kwds)
  return _exit_wrapper
@@ -571,11 +588,26 @@ def push_async_exit(self, exit):
  self._push_async_cm_exit(exit, exit_method)
  return exit # Allow use as a decorator
 
- def push_async_callback(self, callback, *args, **kwds):
+ def push_async_callback(*args, **kwds):
  """Registers an arbitrary coroutine function and arguments.
 
  Cannot suppress exceptions.
  """
+ if len(args) >= 2:
+ self, callback, *args = args
+ elif not args:
+ raise TypeError("descriptor 'push_async_callback' of "
+ "'AsyncExitStack' object needs an argument")
+ elif 'callback' in kwds:
+ callback = kwds.pop('callback')
+ self, *args = args
+ import warnings
+ warnings.warn("Passing 'callback' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError('push_async_callback expected at least 1 '
+ 'positional argument, got %d' % (len(args)-1))
+
  _exit_wrapper = self._create_async_cb_wrapper(callback, *args, **kwds)
 
  # We changed the signature, so using @wraps is not appropriate, but

Lib/curses/__init__.py

@@ -60,14 +60,25 @@ def start_color():
 # raises an exception, wrapper() will restore the terminal to a sane state so
 # you can read the resulting traceback.
 
-def wrapper(func, *args, **kwds):
+def wrapper(*args, **kwds):
  """Wrapper function that initializes curses and calls another function,
  restoring normal keyboard/screen behavior on error.
  The callable object 'func' is then passed the main window 'stdscr'
  as its first argument, followed by any other arguments passed to
  wrapper().
  """
 
+ if args:
+ func, *args = args
+ elif 'func' in kwds:
+ func = kwds.pop('func')
+ import warnings
+ warnings.warn("Passing 'func' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError('wrapper expected at least 1 positional argument, '
+ 'got %d' % len(args))
+
  try:
  # Initialize curses
  stdscr = initscr()

Lib/functools.py

@@ -354,7 +354,23 @@ class partialmethod(object):
  callables as instance methods.
  """
 
- def __init__(self, func, *args, **keywords):
+ def __init__(*args, **keywords):
+ if len(args) >= 2:
+ self, func, *args = args
+ elif not args:
+ raise TypeError("descriptor '__init__' of partialmethod "
+ "needs an argument")
+ elif 'func' in keywords:
+ func = keywords.pop('func')
+ self, *args = args
+ import warnings
+ warnings.warn("Passing 'func' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ raise TypeError("type 'partialmethod' takes at least one argument, "
+ "got %d" % (len(args)-1))
+ args = tuple(args)
+
  if not callable(func) and not hasattr(func, "__get__"):
  raise TypeError("{!r} is not callable or a descriptor"
  .format(func))

Lib/multiprocessing/managers.py

@@ -358,10 +358,36 @@ def shutdown(self, c):
  finally:
  self.stop_event.set()
 
- def create(self, c, typeid, *args, **kwds):
+ def create(*args, **kwds):
  '''
  Create a new shared object and return its id
  '''
+ if len(args) >= 3:
+ self, c, typeid, *args = args
+ elif not args:
+ raise TypeError("descriptor 'create' of 'Server' object "
+ "needs an argument")
+ else:
+ if 'typeid' not in kwds:
+ raise TypeError('create expected at least 2 positional '
+ 'arguments, got %d' % (len(args)-1))
+ typeid = kwds.pop('typeid')
+ if len(args) >= 2:
+ self, c, *args = args
+ import warnings
+ warnings.warn("Passing 'typeid' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ else:
+ if 'c' not in kwds:
+ raise TypeError('create expected at least 2 positional '
+ 'arguments, got %d' % (len(args)-1))
+ c = kwds.pop('c')
+ self, *args = args
+ import warnings
+ warnings.warn("Passing 'c' as keyword argument is deprecated",
+ DeprecationWarning, stacklevel=2)
+ args = tuple(args)
+
  with self.mutex:
  callable, exposed, method_to_typeid, proxytype = \
  self.registry[typeid]
@@ -583,10 +609,13 @@ def _run_server(cls, registry, address, authkey, serializer, writer,
  util.info('manager serving at %r', server.address)
  server.serve_forever()
 
- def _create(self, typeid, *args, **kwds):
+ def _create(*args, **kwds):
  '''
  Create a new shared object; return the token and exposed tuple
  '''
+ self, typeid, *args = args
+ args = tuple(args)
+
  assert self._state.value == State.STARTED, 'server not yet started'
  conn = self._Client(self._address, authkey=self._authkey)
  try:
@@ -1261,15 +1290,25 @@ def __init__(self, *args, **kwargs):
  _SharedMemoryTracker(f"shmm_{self.address}_{getpid()}")
  util.debug(f"SharedMemoryServer started by pid {getpid()}")
 
- def create(self, c, typeid, *args, **kwargs):
+ def create(*args, **kwargs):
  """Create a new distributed-shared object (not backed by a shared
  memory block) and return its id to be used in a Proxy Object."""
  # Unless set up as a shared proxy, don't make shared_memory_context
  # a standard part of kwargs. This makes things easier for supplying
  # simple functions.
+ if len(args) >= 3:
+ typeod = args[2]
+ elif 'typeid' in kwargs:
+ typeid = kwargs['typeid']
+ elif not args:
+ raise TypeError("descriptor 'create' of 'SharedMemoryServer' "
+ "object needs an argument")
+ else:
+ raise TypeError('create expected at least 2 positional '
+ 'arguments, got %d' % (len(args)-1))
  if hasattr(self.registry[typeid][-1], "_shared_memory_proxy"):
  kwargs['shared_memory_context'] = self.shared_memory_context
- return Server.create(self, c, typeid, *args, **kwargs)
+ return Server.create(*args, **kwargs)
 
  def shutdown(self, c):
  "Call unlink() on all tracked shared memory, terminate the Server."