[3.9] bpo-37116: Use PEP 570 syntax for positional-only parameters.

Lib/_collections_abc.py

@@ -821,30 +821,21 @@ def clear(self):
         except KeyError:
             pass
 
-    def update(*args, **kwds):
+    def update(self, other=(), /, **kwds):
         ''' D.update([E, ]**F) -> None.  Update D from mapping/iterable E and F.
             If E present and has a .keys() method, does:     for k in E: D[k] = E[k]
             If E present and lacks .keys() method, does:     for (k, v) in E: D[k] = v
             In either case, this is followed by: for k, v in F.items(): D[k] = v
         '''
-        if not args:
-            raise TypeError("descriptor 'update' of 'MutableMapping' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('update expected at most 1 arguments, got %d' %
-                            len(args))
-        if args:
-            other = args[0]
-            if isinstance(other, Mapping):
-                for key in other:
-                    self[key] = other[key]
-            elif hasattr(other, "keys"):
-                for key in other.keys():
-                    self[key] = other[key]
-            else:
-                for key, value in other:
-                    self[key] = value
+        if isinstance(other, Mapping):
+            for key in other:
+                self[key] = other[key]
+        elif hasattr(other, "keys"):
+            for key in other.keys():
+                self[key] = other[key]
+        else:
+            for key, value in other:
+                self[key] = value
         for key, value in kwds.items():
             self[key] = value
 

Lib/_py_abc.py

@@ -32,7 +32,7 @@ class ABCMeta(type):
     #       external code.
     _abc_invalidation_counter = 0
 
-    def __new__(mcls, name, bases, namespace, **kwargs):
+    def __new__(mcls, name, bases, namespace, /, **kwargs):
         cls = super().__new__(mcls, name, bases, namespace, **kwargs)
         # Compute set of abstract method names
         abstracts = {name

Lib/_threading_local.py

@@ -56,7 +56,7 @@
 
   >>> class MyLocal(local):
   ...     number = 2
-  ...     def __init__(self, **kw):
+  ...     def __init__(self, /, **kw):
   ...         self.__dict__.update(kw)
   ...     def squared(self):
   ...         return self.number ** 2
@@ -204,7 +204,7 @@ def _patch(self):
 class local:
     __slots__ = '_local__impl', '__dict__'
 
-    def __new__(cls, *args, **kw):
+    def __new__(cls, /, *args, **kw):
         if (args or kw) and (cls.__init__ is object.__init__):
             raise TypeError("Initialization arguments are not supported")
         self = object.__new__(cls)

Lib/bdb.py

@@ -618,26 +618,11 @@ def runctx(self, cmd, globals, locals):
 
     # This method is more useful to debug a single function call.
 
-    def runcall(*args, **kwds):
+    def runcall(self, func, /, *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

@@ -103,22 +103,7 @@ def runctx(self, cmd, globals, locals):
         return self
 
     # This method is more useful to profile a single function call.
-    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))
-
+    def runcall(self, func, /, *args, **kw):
         self.enable()
         try:
             return func(*args, **kw)

Lib/collections/__init__.py

@@ -93,24 +93,18 @@ class OrderedDict(dict):
     # Individual links are kept alive by the hard reference in self.__map.
     # Those hard references disappear when a key is deleted from an OrderedDict.
 
-    def __init__(*args, **kwds):
+    def __init__(self, other=(), /, **kwds):
         '''Initialize an ordered dictionary.  The signature is the same as
         regular dictionaries.  Keyword argument order is preserved.
         '''
-        if not args:
-            raise TypeError("descriptor '__init__' of 'OrderedDict' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
         try:
             self.__root
         except AttributeError:
             self.__hardroot = _Link()
             self.__root = root = _proxy(self.__hardroot)
             root.prev = root.next = root
             self.__map = {}
-        self.__update(*args, **kwds)
+        self.__update(other, **kwds)
 
     def __setitem__(self, key, value,
                     dict_setitem=dict.__setitem__, proxy=_proxy, Link=_Link):
@@ -413,8 +407,8 @@ def _make(cls, iterable):
     _make.__func__.__doc__ = (f'Make a new {typename} object from a sequence '
                               'or iterable')
 
-    def _replace(_self, **kwds):
-        result = _self._make(_map(kwds.pop, field_names, _self))
+    def _replace(self, /, **kwds):
+        result = self._make(_map(kwds.pop, field_names, self))
         if kwds:
             raise ValueError(f'Got unexpected field names: {list(kwds)!r}')
         return result
@@ -543,7 +537,7 @@ class Counter(dict):
     #   http://code.activestate.com/recipes/259174/
     #   Knuth, TAOCP Vol. II section 4.6.3
 
-    def __init__(*args, **kwds):
+    def __init__(self, iterable=None, /, **kwds):
         '''Create a new, empty Counter object.  And if given, count elements
         from an input iterable.  Or, initialize the count from another mapping
         of elements to their counts.
@@ -554,14 +548,8 @@ def __init__(*args, **kwds):
         >>> c = Counter(a=4, b=2)                   # a new counter from keyword args
 
         '''
-        if not args:
-            raise TypeError("descriptor '__init__' of 'Counter' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
         super(Counter, self).__init__()
-        self.update(*args, **kwds)
+        self.update(iterable, **kwds)
 
     def __missing__(self, key):
         'The count of elements not in the Counter is zero.'
@@ -617,7 +605,7 @@ def fromkeys(cls, iterable, v=None):
         raise NotImplementedError(
             'Counter.fromkeys() is undefined.  Use Counter(iterable) instead.')
 
-    def update(*args, **kwds):
+    def update(self, iterable=None, /, **kwds):
         '''Like dict.update() but add counts instead of replacing them.
 
         Source can be an iterable, a dictionary, or another Counter instance.
@@ -637,13 +625,6 @@ def update(*args, **kwds):
         # contexts.  Instead, we implement straight-addition.  Both the inputs
         # and outputs are allowed to contain zero and negative counts.
 
-        if not args:
-            raise TypeError("descriptor 'update' of 'Counter' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
-        iterable = args[0] if args else None
         if iterable is not None:
             if isinstance(iterable, _collections_abc.Mapping):
                 if self:
@@ -657,7 +638,7 @@ def update(*args, **kwds):
         if kwds:
             self.update(kwds)
 
-    def subtract(*args, **kwds):
+    def subtract(self, iterable=None, /, **kwds):
         '''Like dict.update() but subtracts counts instead of replacing them.
         Counts can be reduced below zero.  Both the inputs and outputs are
         allowed to contain zero and negative counts.
@@ -673,13 +654,6 @@ def subtract(*args, **kwds):
         -1
 
         '''
-        if not args:
-            raise TypeError("descriptor 'subtract' of 'Counter' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
-        iterable = args[0] if args else None
         if iterable is not None:
             self_get = self.get
             if isinstance(iterable, _collections_abc.Mapping):
@@ -997,26 +971,11 @@ def clear(self):
 class UserDict(_collections_abc.MutableMapping):
 
     # Start by filling-out the abstract methods
-    def __init__(*args, **kwargs):
-        if not args:
-            raise TypeError("descriptor '__init__' of 'UserDict' object "
-                            "needs an argument")
-        self, *args = args
-        if len(args) > 1:
-            raise TypeError('expected at most 1 arguments, got %d' % len(args))
-        if args:
-            dict = args[0]
-        elif 'dict' in kwargs:
-            dict = kwargs.pop('dict')
-            import warnings
-            warnings.warn("Passing 'dict' as keyword argument is deprecated",
-                          DeprecationWarning, stacklevel=2)
-        else:
-            dict = None
+    def __init__(self, dict=None, /, **kwargs):
         self.data = {}
         if dict is not None:
             self.update(dict)
-        if len(kwargs):
+        if kwargs:
             self.update(kwargs)
     def __len__(self): return len(self.data)
     def __getitem__(self, key):
@@ -1121,7 +1080,7 @@ def copy(self): return self.__class__(self)
     def count(self, item): return self.data.count(item)
     def index(self, item, *args): return self.data.index(item, *args)
     def reverse(self): self.data.reverse()
-    def sort(self, *args, **kwds): self.data.sort(*args, **kwds)
+    def sort(self, /, *args, **kwds): self.data.sort(*args, **kwds)
     def extend(self, other):
         if isinstance(other, UserList):
             self.data.extend(other.data)
@@ -1221,7 +1180,7 @@ def find(self, sub, start=0, end=_sys.maxsize):
         if isinstance(sub, UserString):
             sub = sub.data
         return self.data.find(sub, start, end)
-    def format(self, *args, **kwds):
+    def format(self, /, *args, **kwds):
         return self.data.format(*args, **kwds)
     def format_map(self, mapping):
         return self.data.format_map(mapping)

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(*args, **kwargs):
+    def submit(self, fn, /, *args, **kwargs):
         """Submits a callable to be executed with the given arguments.
 
         Schedules the callable to be executed as fn(*args, **kwargs) and returns
@@ -553,19 +553,6 @@ def submit(*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

@@ -594,22 +594,7 @@ def _adjust_process_count(self):
             p.start()
             self._processes[p.pid] = p
 
-    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))
-
+    def submit(self, fn, /, *args, **kwargs):
         with self._shutdown_lock:
             if self._broken:
                 raise BrokenProcessPool(self._broken)

Lib/concurrent/futures/thread.py

@@ -142,22 +142,7 @@ def __init__(self, max_workers=None, thread_name_prefix='',
         self._initializer = initializer
         self._initargs = initargs
 
-    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))
-
+    def submit(self, fn, /, *args, **kwargs):
         with self._shutdown_lock:
             if self._broken:
                 raise BrokenThreadPool(self._broken)