Issue #15008: Implement PEP 362 "Signature Objects".
Patch by Yury Selivanov.
diff --git a/Lib/inspect.py b/Lib/inspect.py
index c3338f2..484c9c3 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -22,12 +22,14 @@
getouterframes(), getinnerframes() - get info about frames
currentframe() - get the current stack frame
stack(), trace() - get info about frames on the stack or in a traceback
+
+ signature() - get a Signature object for the callable
"""
# This module is in the public domain. No warranties.
-__author__ = 'Ka-Ping Yee <ping@lfw.org>'
-__date__ = '1 Jan 2001'
+__author__ = ('Ka-Ping Yee <ping@lfw.org>',
+ 'Yury Selivanov <yselivanov@sprymix.com>')
import imp
import importlib.machinery
@@ -39,8 +41,9 @@
import tokenize
import types
import warnings
+import functools
from operator import attrgetter
-from collections import namedtuple
+from collections import namedtuple, OrderedDict
# Create constants for the compiler flags in Include/code.h
# We try to get them from dis to avoid duplication, but fall
@@ -1223,3 +1226,769 @@
if generator.gi_frame.f_lasti == -1:
return GEN_CREATED
return GEN_SUSPENDED
+
+
+###############################################################################
+### Function Signature Object (PEP 362)
+###############################################################################
+
+
+_WrapperDescriptor = type(type.__call__)
+_MethodWrapper = type(all.__call__)
+
+_NonUserDefinedCallables = (_WrapperDescriptor,
+ _MethodWrapper,
+ types.BuiltinFunctionType)
+
+
+def _get_user_defined_method(cls, method_name):
+ try:
+ meth = getattr(cls, method_name)
+ except AttributeError:
+ return
+ else:
+ if not isinstance(meth, _NonUserDefinedCallables):
+ # Once '__signature__' will be added to 'C'-level
+ # callables, this check won't be necessary
+ return meth
+
+
+def signature(obj):
+ '''Get a signature object for the passed callable.'''
+
+ if not callable(obj):
+ raise TypeError('{!r} is not a callable object'.format(obj))
+
+ if isinstance(obj, types.MethodType):
+ # In this case we skip the first parameter of the underlying
+ # function (usually `self` or `cls`).
+ sig = signature(obj.__func__)
+ return sig.replace(parameters=tuple(sig.parameters.values())[1:])
+
+ try:
+ sig = obj.__signature__
+ except AttributeError:
+ pass
+ else:
+ if sig is not None:
+ return sig
+
+ try:
+ # Was this function wrapped by a decorator?
+ wrapped = obj.__wrapped__
+ except AttributeError:
+ pass
+ else:
+ return signature(wrapped)
+
+ if isinstance(obj, types.FunctionType):
+ return Signature.from_function(obj)
+
+ if isinstance(obj, functools.partial):
+ sig = signature(obj.func)
+
+ new_params = OrderedDict(sig.parameters.items())
+
+ partial_args = obj.args or ()
+ partial_keywords = obj.keywords or {}
+ try:
+ ba = sig.bind_partial(*partial_args, **partial_keywords)
+ except TypeError as ex:
+ msg = 'partial object {!r} has incorrect arguments'.format(obj)
+ raise ValueError(msg) from ex
+
+ for arg_name, arg_value in ba.arguments.items():
+ param = new_params[arg_name]
+ if arg_name in partial_keywords:
+ # We set a new default value, because the following code
+ # is correct:
+ #
+ # >>> def foo(a): print(a)
+ # >>> print(partial(partial(foo, a=10), a=20)())
+ # 20
+ # >>> print(partial(partial(foo, a=10), a=20)(a=30))
+ # 30
+ #
+ # So, with 'partial' objects, passing a keyword argument is
+ # like setting a new default value for the corresponding
+ # parameter
+ #
+ # We also mark this parameter with '_partial_kwarg'
+ # flag. Later, in '_bind', the 'default' value of this
+ # parameter will be added to 'kwargs', to simulate
+ # the 'functools.partial' real call.
+ new_params[arg_name] = param.replace(default=arg_value,
+ _partial_kwarg=True)
+
+ elif (param.kind not in (_VAR_KEYWORD, _VAR_POSITIONAL) and
+ not param._partial_kwarg):
+ new_params.pop(arg_name)
+
+ return sig.replace(parameters=new_params.values())
+
+ sig = None
+ if isinstance(obj, type):
+ # obj is a class or a metaclass
+
+ # First, let's see if it has an overloaded __call__ defined
+ # in its metaclass
+ call = _get_user_defined_method(type(obj), '__call__')
+ if call is not None:
+ sig = signature(call)
+ else:
+ # Now we check if the 'obj' class has a '__new__' method
+ new = _get_user_defined_method(obj, '__new__')
+ if new is not None:
+ sig = signature(new)
+ else:
+ # Finally, we should have at least __init__ implemented
+ init = _get_user_defined_method(obj, '__init__')
+ if init is not None:
+ sig = signature(init)
+ elif not isinstance(obj, _NonUserDefinedCallables):
+ # An object with __call__
+ # We also check that the 'obj' is not an instance of
+ # _WrapperDescriptor or _MethodWrapper to avoid
+ # infinite recursion (and even potential segfault)
+ call = _get_user_defined_method(type(obj), '__call__')
+ if call is not None:
+ sig = signature(call)
+
+ if sig is not None:
+ # For classes and objects we skip the first parameter of their
+ # __call__, __new__, or __init__ methods
+ return sig.replace(parameters=tuple(sig.parameters.values())[1:])
+
+ if isinstance(obj, types.BuiltinFunctionType):
+ # Raise a nicer error message for builtins
+ msg = 'no signature found for builtin function {!r}'.format(obj)
+ raise ValueError(msg)
+
+ raise ValueError('callable {!r} is not supported by signature'.format(obj))
+
+
+class _void:
+ '''A private marker - used in Parameter & Signature'''
+
+
+class _empty:
+ pass
+
+
+class _ParameterKind(int):
+ def __new__(self, *args, name):
+ obj = int.__new__(self, *args)
+ obj._name = name
+ return obj
+
+ def __str__(self):
+ return self._name
+
+ def __repr__(self):
+ return '<_ParameterKind: {!r}>'.format(self._name)
+
+
+_POSITIONAL_ONLY = _ParameterKind(0, name='POSITIONAL_ONLY')
+_POSITIONAL_OR_KEYWORD = _ParameterKind(1, name='POSITIONAL_OR_KEYWORD')
+_VAR_POSITIONAL = _ParameterKind(2, name='VAR_POSITIONAL')
+_KEYWORD_ONLY = _ParameterKind(3, name='KEYWORD_ONLY')
+_VAR_KEYWORD = _ParameterKind(4, name='VAR_KEYWORD')
+
+
+class Parameter:
+ '''Represents a parameter in a function signature.
+
+ Has the following public attributes:
+
+ * name : str
+ The name of the parameter as a string.
+ * default : object
+ The default value for the parameter if specified. If the
+ parameter has no default value, this attribute is not set.
+ * annotation
+ The annotation for the parameter if specified. If the
+ parameter has no annotation, this attribute is not set.
+ * kind : str
+ Describes how argument values are bound to the parameter.
+ Possible values: `Parameter.POSITIONAL_ONLY`,
+ `Parameter.POSITIONAL_OR_KEYWORD`, `Parameter.VAR_POSITIONAL`,
+ `Parameter.KEYWORD_ONLY`, `Parameter.VAR_KEYWORD`.
+ '''
+
+ __slots__ = ('_name', '_kind', '_default', '_annotation', '_partial_kwarg')
+
+ POSITIONAL_ONLY = _POSITIONAL_ONLY
+ POSITIONAL_OR_KEYWORD = _POSITIONAL_OR_KEYWORD
+ VAR_POSITIONAL = _VAR_POSITIONAL
+ KEYWORD_ONLY = _KEYWORD_ONLY
+ VAR_KEYWORD = _VAR_KEYWORD
+
+ empty = _empty
+
+ def __init__(self, name, kind, *, default=_empty, annotation=_empty,
+ _partial_kwarg=False):
+
+ if kind not in (_POSITIONAL_ONLY, _POSITIONAL_OR_KEYWORD,
+ _VAR_POSITIONAL, _KEYWORD_ONLY, _VAR_KEYWORD):
+ raise ValueError("invalid value for 'Parameter.kind' attribute")
+ self._kind = kind
+
+ if default is not _empty:
+ if kind in (_VAR_POSITIONAL, _VAR_KEYWORD):
+ msg = '{} parameters cannot have default values'.format(kind)
+ raise ValueError(msg)
+ self._default = default
+ self._annotation = annotation
+
+ if name is None:
+ if kind != _POSITIONAL_ONLY:
+ raise ValueError("None is not a valid name for a "
+ "non-positional-only parameter")
+ self._name = name
+ else:
+ name = str(name)
+ if kind != _POSITIONAL_ONLY and not name.isidentifier():
+ msg = '{!r} is not a valid parameter name'.format(name)
+ raise ValueError(msg)
+ self._name = name
+
+ self._partial_kwarg = _partial_kwarg
+
+ @property
+ def name(self):
+ return self._name
+
+ @property
+ def default(self):
+ return self._default
+
+ @property
+ def annotation(self):
+ return self._annotation
+
+ @property
+ def kind(self):
+ return self._kind
+
+ def replace(self, *, name=_void, kind=_void, annotation=_void,
+ default=_void, _partial_kwarg=_void):
+ '''Creates a customized copy of the Parameter.'''
+
+ if name is _void:
+ name = self._name
+
+ if kind is _void:
+ kind = self._kind
+
+ if annotation is _void:
+ annotation = self._annotation
+
+ if default is _void:
+ default = self._default
+
+ if _partial_kwarg is _void:
+ _partial_kwarg = self._partial_kwarg
+
+ return type(self)(name, kind, default=default, annotation=annotation,
+ _partial_kwarg=_partial_kwarg)
+
+ def __str__(self):
+ kind = self.kind
+
+ formatted = self._name
+ if kind == _POSITIONAL_ONLY:
+ if formatted is None:
+ formatted = ''
+ formatted = '<{}>'.format(formatted)
+
+ # Add annotation and default value
+ if self._annotation is not _empty:
+ formatted = '{}:{}'.format(formatted,
+ formatannotation(self._annotation))
+
+ if self._default is not _empty:
+ formatted = '{}={}'.format(formatted, repr(self._default))
+
+ if kind == _VAR_POSITIONAL:
+ formatted = '*' + formatted
+ elif kind == _VAR_KEYWORD:
+ formatted = '**' + formatted
+
+ return formatted
+
+ def __repr__(self):
+ return '<{} at {:#x} {!r}>'.format(self.__class__.__name__,
+ id(self), self.name)
+
+ def __eq__(self, other):
+ return (issubclass(other.__class__, Parameter) and
+ self._name == other._name and
+ self._kind == other._kind and
+ self._default == other._default and
+ self._annotation == other._annotation)
+
+ def __ne__(self, other):
+ return not self.__eq__(other)
+
+
+class BoundArguments:
+ '''Result of `Signature.bind` call. Holds the mapping of arguments
+ to the function's parameters.
+
+ Has the following public attributes:
+
+ * arguments : OrderedDict
+ An ordered mutable mapping of parameters' names to arguments' values.
+ Does not contain arguments' default values.
+ * signature : Signature
+ The Signature object that created this instance.
+ * args : tuple
+ Tuple of positional arguments values.
+ * kwargs : dict
+ Dict of keyword arguments values.
+ '''
+
+ def __init__(self, signature, arguments):
+ self.arguments = arguments
+ self._signature = signature
+
+ @property
+ def signature(self):
+ return self._signature
+
+ @property
+ def args(self):
+ args = []
+ for param_name, param in self._signature.parameters.items():
+ if (param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY) or
+ param._partial_kwarg):
+ # Keyword arguments mapped by 'functools.partial'
+ # (Parameter._partial_kwarg is True) are mapped
+ # in 'BoundArguments.kwargs', along with VAR_KEYWORD &
+ # KEYWORD_ONLY
+ break
+
+ try:
+ arg = self.arguments[param_name]
+ except KeyError:
+ # We're done here. Other arguments
+ # will be mapped in 'BoundArguments.kwargs'
+ break
+ else:
+ if param.kind == _VAR_POSITIONAL:
+ # *args
+ args.extend(arg)
+ else:
+ # plain argument
+ args.append(arg)
+
+ return tuple(args)
+
+ @property
+ def kwargs(self):
+ kwargs = {}
+ kwargs_started = False
+ for param_name, param in self._signature.parameters.items():
+ if not kwargs_started:
+ if (param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY) or
+ param._partial_kwarg):
+ kwargs_started = True
+ else:
+ if param_name not in self.arguments:
+ kwargs_started = True
+ continue
+
+ if not kwargs_started:
+ continue
+
+ try:
+ arg = self.arguments[param_name]
+ except KeyError:
+ pass
+ else:
+ if param.kind == _VAR_KEYWORD:
+ # **kwargs
+ kwargs.update(arg)
+ else:
+ # plain keyword argument
+ kwargs[param_name] = arg
+
+ return kwargs
+
+ def __eq__(self, other):
+ return (issubclass(other.__class__, BoundArguments) and
+ self.signature == other.signature and
+ self.arguments == other.arguments)
+
+ def __ne__(self, other):
+ return not self.__eq__(other)
+
+
+class Signature:
+ '''A Signature object represents the overall signature of a function.
+ It stores a Parameter object for each parameter accepted by the
+ function, as well as information specific to the function itself.
+
+ A Signature object has the following public attributes and methods:
+
+ * parameters : OrderedDict
+ An ordered mapping of parameters' names to the corresponding
+ Parameter objects (keyword-only arguments are in the same order
+ as listed in `code.co_varnames`).
+ * return_annotation : object
+ The annotation for the return type of the function if specified.
+ If the function has no annotation for its return type, this
+ attribute is not set.
+ * bind(*args, **kwargs) -> BoundArguments
+ Creates a mapping from positional and keyword arguments to
+ parameters.
+ * bind_partial(*args, **kwargs) -> BoundArguments
+ Creates a partial mapping from positional and keyword arguments
+ to parameters (simulating 'functools.partial' behavior.)
+ '''
+
+ __slots__ = ('_return_annotation', '_parameters')
+
+ _parameter_cls = Parameter
+ _bound_arguments_cls = BoundArguments
+
+ empty = _empty
+
+ def __init__(self, parameters=None, *, return_annotation=_empty,
+ __validate_parameters__=True):
+ '''Constructs Signature from the given list of Parameter
+ objects and 'return_annotation'. All arguments are optional.
+ '''
+
+ if parameters is None:
+ params = OrderedDict()
+ else:
+ if __validate_parameters__:
+ params = OrderedDict()
+ top_kind = _POSITIONAL_ONLY
+
+ for idx, param in enumerate(parameters):
+ kind = param.kind
+ if kind < top_kind:
+ msg = 'wrong parameter order: {} before {}'
+ msg = msg.format(top_kind, param.kind)
+ raise ValueError(msg)
+ else:
+ top_kind = kind
+
+ name = param.name
+ if name is None:
+ name = str(idx)
+ param = param.replace(name=name)
+
+ if name in params:
+ msg = 'duplicate parameter name: {!r}'.format(name)
+ raise ValueError(msg)
+ params[name] = param
+ else:
+ params = OrderedDict(((param.name, param)
+ for param in parameters))
+
+ self._parameters = types.MappingProxyType(params)
+ self._return_annotation = return_annotation
+
+ @classmethod
+ def from_function(cls, func):
+ '''Constructs Signature for the given python function'''
+
+ if not isinstance(func, types.FunctionType):
+ raise TypeError('{!r} is not a Python function'.format(func))
+
+ Parameter = cls._parameter_cls
+
+ # Parameter information.
+ func_code = func.__code__
+ pos_count = func_code.co_argcount
+ arg_names = func_code.co_varnames
+ positional = tuple(arg_names[:pos_count])
+ keyword_only_count = func_code.co_kwonlyargcount
+ keyword_only = arg_names[pos_count:(pos_count + keyword_only_count)]
+ annotations = func.__annotations__
+ defaults = func.__defaults__
+ kwdefaults = func.__kwdefaults__
+
+ if defaults:
+ pos_default_count = len(defaults)
+ else:
+ pos_default_count = 0
+
+ parameters = []
+
+ # Non-keyword-only parameters w/o defaults.
+ non_default_count = pos_count - pos_default_count
+ for name in positional[:non_default_count]:
+ annotation = annotations.get(name, _empty)
+ parameters.append(Parameter(name, annotation=annotation,
+ kind=_POSITIONAL_OR_KEYWORD))
+
+ # ... w/ defaults.
+ for offset, name in enumerate(positional[non_default_count:]):
+ annotation = annotations.get(name, _empty)
+ parameters.append(Parameter(name, annotation=annotation,
+ kind=_POSITIONAL_OR_KEYWORD,
+ default=defaults[offset]))
+
+ # *args
+ if func_code.co_flags & 0x04:
+ name = arg_names[pos_count + keyword_only_count]
+ annotation = annotations.get(name, _empty)
+ parameters.append(Parameter(name, annotation=annotation,
+ kind=_VAR_POSITIONAL))
+
+ # Keyword-only parameters.
+ for name in keyword_only:
+ default = _empty
+ if kwdefaults is not None:
+ default = kwdefaults.get(name, _empty)
+
+ annotation = annotations.get(name, _empty)
+ parameters.append(Parameter(name, annotation=annotation,
+ kind=_KEYWORD_ONLY,
+ default=default))
+ # **kwargs
+ if func_code.co_flags & 0x08:
+ index = pos_count + keyword_only_count
+ if func_code.co_flags & 0x04:
+ index += 1
+
+ name = arg_names[index]
+ annotation = annotations.get(name, _empty)
+ parameters.append(Parameter(name, annotation=annotation,
+ kind=_VAR_KEYWORD))
+
+ return cls(parameters,
+ return_annotation=annotations.get('return', _empty),
+ __validate_parameters__=False)
+
+ @property
+ def parameters(self):
+ return self._parameters
+
+ @property
+ def return_annotation(self):
+ return self._return_annotation
+
+ def replace(self, *, parameters=_void, return_annotation=_void):
+ '''Creates a customized copy of the Signature.
+ Pass 'parameters' and/or 'return_annotation' arguments
+ to override them in the new copy.
+ '''
+
+ if parameters is _void:
+ parameters = self.parameters.values()
+
+ if return_annotation is _void:
+ return_annotation = self._return_annotation
+
+ return type(self)(parameters,
+ return_annotation=return_annotation)
+
+ def __eq__(self, other):
+ if (not issubclass(type(other), Signature) or
+ self.return_annotation != other.return_annotation or
+ len(self.parameters) != len(other.parameters)):
+ return False
+
+ other_positions = {param: idx
+ for idx, param in enumerate(other.parameters.keys())}
+
+ for idx, (param_name, param) in enumerate(self.parameters.items()):
+ if param.kind == _KEYWORD_ONLY:
+ try:
+ other_param = other.parameters[param_name]
+ except KeyError:
+ return False
+ else:
+ if param != other_param:
+ return False
+ else:
+ try:
+ other_idx = other_positions[param_name]
+ except KeyError:
+ return False
+ else:
+ if (idx != other_idx or
+ param != other.parameters[param_name]):
+ return False
+
+ return True
+
+ def __ne__(self, other):
+ return not self.__eq__(other)
+
+ def _bind(self, args, kwargs, *, partial=False):
+ '''Private method. Don't use directly.'''
+
+ arguments = OrderedDict()
+
+ parameters = iter(self.parameters.values())
+ parameters_ex = ()
+ arg_vals = iter(args)
+
+ if partial:
+ # Support for binding arguments to 'functools.partial' objects.
+ # See 'functools.partial' case in 'signature()' implementation
+ # for details.
+ for param_name, param in self.parameters.items():
+ if (param._partial_kwarg and param_name not in kwargs):
+ # Simulating 'functools.partial' behavior
+ kwargs[param_name] = param.default
+
+ while True:
+ # Let's iterate through the positional arguments and corresponding
+ # parameters
+ try:
+ arg_val = next(arg_vals)
+ except StopIteration:
+ # No more positional arguments
+ try:
+ param = next(parameters)
+ except StopIteration:
+ # No more parameters. That's it. Just need to check that
+ # we have no `kwargs` after this while loop
+ break
+ else:
+ if param.kind == _VAR_POSITIONAL:
+ # That's OK, just empty *args. Let's start parsing
+ # kwargs
+ break
+ elif param.name in kwargs:
+ if param.kind == _POSITIONAL_ONLY:
+ msg = '{arg!r} parameter is positional only, ' \
+ 'but was passed as a keyword'
+ msg = msg.format(arg=param.name)
+ raise TypeError(msg) from None
+ parameters_ex = (param,)
+ break
+ elif (param.kind == _VAR_KEYWORD or
+ param.default is not _empty):
+ # That's fine too - we have a default value for this
+ # parameter. So, lets start parsing `kwargs`, starting
+ # with the current parameter
+ parameters_ex = (param,)
+ break
+ else:
+ if partial:
+ parameters_ex = (param,)
+ break
+ else:
+ msg = '{arg!r} parameter lacking default value'
+ msg = msg.format(arg=param.name)
+ raise TypeError(msg) from None
+ else:
+ # We have a positional argument to process
+ try:
+ param = next(parameters)
+ except StopIteration:
+ raise TypeError('too many positional arguments') from None
+ else:
+ if param.kind in (_VAR_KEYWORD, _KEYWORD_ONLY):
+ # Looks like we have no parameter for this positional
+ # argument
+ raise TypeError('too many positional arguments')
+
+ if param.kind == _VAR_POSITIONAL:
+ # We have an '*args'-like argument, let's fill it with
+ # all positional arguments we have left and move on to
+ # the next phase
+ values = [arg_val]
+ values.extend(arg_vals)
+ arguments[param.name] = tuple(values)
+ break
+
+ if param.name in kwargs:
+ raise TypeError('multiple values for argument '
+ '{arg!r}'.format(arg=param.name))
+
+ arguments[param.name] = arg_val
+
+ # Now, we iterate through the remaining parameters to process
+ # keyword arguments
+ kwargs_param = None
+ for param in itertools.chain(parameters_ex, parameters):
+ if param.kind == _POSITIONAL_ONLY:
+ # This should never happen in case of a properly built
+ # Signature object (but let's have this check here
+ # to ensure correct behaviour just in case)
+ raise TypeError('{arg!r} parameter is positional only, '
+ 'but was passed as a keyword'. \
+ format(arg=param.name))
+
+ if param.kind == _VAR_KEYWORD:
+ # Memorize that we have a '**kwargs'-like parameter
+ kwargs_param = param
+ continue
+
+ param_name = param.name
+ try:
+ arg_val = kwargs.pop(param_name)
+ except KeyError:
+ # We have no value for this parameter. It's fine though,
+ # if it has a default value, or it is an '*args'-like
+ # parameter, left alone by the processing of positional
+ # arguments.
+ if (not partial and param.kind != _VAR_POSITIONAL and
+ param.default is _empty):
+ raise TypeError('{arg!r} parameter lacking default value'. \
+ format(arg=param_name)) from None
+
+ else:
+ arguments[param_name] = arg_val
+
+ if kwargs:
+ if kwargs_param is not None:
+ # Process our '**kwargs'-like parameter
+ arguments[kwargs_param.name] = kwargs
+ else:
+ raise TypeError('too many keyword arguments')
+
+ return self._bound_arguments_cls(self, arguments)
+
+ def bind(self, *args, **kwargs):
+ '''Get a BoundArguments object, that maps the passed `args`
+ and `kwargs` to the function's signature. Raises `TypeError`
+ if the passed arguments can not be bound.
+ '''
+ return self._bind(args, kwargs)
+
+ def bind_partial(self, *args, **kwargs):
+ '''Get a BoundArguments object, that partially maps the
+ passed `args` and `kwargs` to the function's signature.
+ Raises `TypeError` if the passed arguments can not be bound.
+ '''
+ return self._bind(args, kwargs, partial=True)
+
+ def __str__(self):
+ result = []
+ render_kw_only_separator = True
+ for idx, param in enumerate(self.parameters.values()):
+ formatted = str(param)
+
+ kind = param.kind
+ if kind == _VAR_POSITIONAL:
+ # OK, we have an '*args'-like parameter, so we won't need
+ # a '*' to separate keyword-only arguments
+ render_kw_only_separator = False
+ elif kind == _KEYWORD_ONLY and render_kw_only_separator:
+ # We have a keyword-only parameter to render and we haven't
+ # rendered an '*args'-like parameter before, so add a '*'
+ # separator to the parameters list ("foo(arg1, *, arg2)" case)
+ result.append('*')
+ # This condition should be only triggered once, so
+ # reset the flag
+ render_kw_only_separator = False
+
+ result.append(formatted)
+
+ rendered = '({})'.format(', '.join(result))
+
+ if self.return_annotation is not _empty:
+ anno = formatannotation(self.return_annotation)
+ rendered += ' -> {}'.format(anno)
+
+ return rendered