inspect: Fix getfullargspec() to not to follow __wrapped__ chains
Initial patch by Nick Coghlan.
This commit is contained in:
Yury Selivanov
parent
4ac30f1792
commit
57d240ef64
105
Lib/inspect.py
105
Lib/inspect.py
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@ -949,9 +949,9 @@ def getfullargspec(func):
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The first four items in the tuple correspond to getargspec().
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"""
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builtin_method_param = None
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if ismethod(func):
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try:
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# Re: `skip_bound_arg=False`
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#
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# There is a notable difference in behaviour between getfullargspec
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# and Signature: the former always returns 'self' parameter for bound
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# methods, whereas the Signature always shows the actual calling
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@ -960,20 +960,15 @@ def getfullargspec(func):
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# To simulate this behaviour, we "unbind" bound methods, to trick
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# inspect.signature to always return their first parameter ("self",
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# usually)
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func = func.__func__
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elif isbuiltin(func):
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# We have a builtin function or method. For that, we check the
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# special '__text_signature__' attribute, provided by the
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# Argument Clinic. If it's a method, we'll need to make sure
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# that its first parameter (usually "self") is always returned
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# (see the previous comment).
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text_signature = getattr(func, '__text_signature__', None)
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if text_signature and text_signature.startswith('($'):
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builtin_method_param = _signature_get_bound_param(text_signature)
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# Re: `follow_wrapper_chains=False`
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#
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# getfullargspec() historically ignored __wrapped__ attributes,
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# so we ensure that remains the case in 3.3+
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try:
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sig = signature(func)
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sig = _signature_internal(func,
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follow_wrapper_chains=False,
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skip_bound_arg=False)
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except Exception as ex:
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# Most of the times 'signature' will raise ValueError.
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# But, it can also raise AttributeError, and, maybe something
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@ -1023,13 +1018,6 @@ def getfullargspec(func):
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# compatibility with 'func.__defaults__'
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defaults = None
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if builtin_method_param and (not args or args[0] != builtin_method_param):
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# `func` is a method, and we always need to return its
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# first parameter -- usually "self" (to be backwards
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# compatible with the previous implementation of
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# getfullargspec)
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args.insert(0, builtin_method_param)
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return FullArgSpec(args, varargs, varkw, defaults,
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kwonlyargs, kwdefaults, annotations)
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@ -1719,7 +1707,7 @@ def _signature_strip_non_python_syntax(signature):
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return clean_signature, self_parameter, last_positional_only
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def _signature_fromstr(cls, obj, s):
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def _signature_fromstr(cls, obj, s, skip_bound_arg=True):
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# Internal helper to parse content of '__text_signature__'
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# and return a Signature based on it
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Parameter = cls._parameter_cls
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@ -1840,7 +1828,7 @@ def _signature_fromstr(cls, obj, s):
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if self_parameter is not None:
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assert parameters
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if getattr(obj, '__self__', None):
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if getattr(obj, '__self__', None) and skip_bound_arg:
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# strip off self, it's already been bound
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parameters.pop(0)
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else:
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@ -1851,8 +1839,21 @@ def _signature_fromstr(cls, obj, s):
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return cls(parameters, return_annotation=cls.empty)
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def signature(obj):
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'''Get a signature object for the passed callable.'''
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def _signature_from_builtin(cls, func, skip_bound_arg=True):
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# Internal helper function to get signature for
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# builtin callables
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if not _signature_is_builtin(func):
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raise TypeError("{!r} is not a Python builtin "
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"function".format(func))
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s = getattr(func, "__text_signature__", None)
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if not s:
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raise ValueError("no signature found for builtin {!r}".format(func))
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return _signature_fromstr(cls, func, s, skip_bound_arg)
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def _signature_internal(obj, follow_wrapper_chains=True, skip_bound_arg=True):
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if not callable(obj):
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raise TypeError('{!r} is not a callable object'.format(obj))
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@ -1860,10 +1861,16 @@ def signature(obj):
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if isinstance(obj, types.MethodType):
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# In this case we skip the first parameter of the underlying
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# function (usually `self` or `cls`).
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sig = signature(obj.__func__)
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sig = _signature_internal(obj.__func__,
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follow_wrapper_chains,
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skip_bound_arg)
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if skip_bound_arg:
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return _signature_bound_method(sig)
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else:
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return sig
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# Was this function wrapped by a decorator?
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if follow_wrapper_chains:
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obj = unwrap(obj, stop=(lambda f: hasattr(f, "__signature__")))
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try:
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@ -1887,7 +1894,9 @@ def signature(obj):
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# (usually `self`, or `cls`) will not be passed
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# automatically (as for boundmethods)
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wrapped_sig = signature(partialmethod.func)
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wrapped_sig = _signature_internal(partialmethod.func,
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follow_wrapper_chains,
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skip_bound_arg)
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sig = _signature_get_partial(wrapped_sig, partialmethod, (None,))
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first_wrapped_param = tuple(wrapped_sig.parameters.values())[0]
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@ -1896,7 +1905,8 @@ def signature(obj):
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return sig.replace(parameters=new_params)
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if _signature_is_builtin(obj):
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return Signature.from_builtin(obj)
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return _signature_from_builtin(Signature, obj,
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skip_bound_arg=skip_bound_arg)
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if isfunction(obj) or _signature_is_functionlike(obj):
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# If it's a pure Python function, or an object that is duck type
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@ -1904,7 +1914,9 @@ def signature(obj):
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return Signature.from_function(obj)
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if isinstance(obj, functools.partial):
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wrapped_sig = signature(obj.func)
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wrapped_sig = _signature_internal(obj.func,
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follow_wrapper_chains,
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skip_bound_arg)
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return _signature_get_partial(wrapped_sig, obj)
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sig = None
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@ -1915,17 +1927,23 @@ def signature(obj):
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# in its metaclass
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call = _signature_get_user_defined_method(type(obj), '__call__')
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if call is not None:
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sig = signature(call)
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sig = _signature_internal(call,
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follow_wrapper_chains,
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skip_bound_arg)
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else:
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# Now we check if the 'obj' class has a '__new__' method
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new = _signature_get_user_defined_method(obj, '__new__')
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if new is not None:
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sig = signature(new)
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sig = _signature_internal(new,
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follow_wrapper_chains,
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skip_bound_arg)
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else:
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# Finally, we should have at least __init__ implemented
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init = _signature_get_user_defined_method(obj, '__init__')
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if init is not None:
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sig = signature(init)
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sig = _signature_internal(init,
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follow_wrapper_chains,
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skip_bound_arg)
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if sig is None:
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# At this point we know, that `obj` is a class, with no user-
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@ -1967,7 +1985,9 @@ def signature(obj):
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call = _signature_get_user_defined_method(type(obj), '__call__')
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if call is not None:
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try:
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sig = signature(call)
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sig = _signature_internal(call,
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follow_wrapper_chains,
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skip_bound_arg)
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except ValueError as ex:
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msg = 'no signature found for {!r}'.format(obj)
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raise ValueError(msg) from ex
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@ -1975,7 +1995,10 @@ def signature(obj):
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if sig is not None:
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# For classes and objects we skip the first parameter of their
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# __call__, __new__, or __init__ methods
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if skip_bound_arg:
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return _signature_bound_method(sig)
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else:
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return sig
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if isinstance(obj, types.BuiltinFunctionType):
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# Raise a nicer error message for builtins
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@ -1984,6 +2007,10 @@ def signature(obj):
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raise ValueError('callable {!r} is not supported by signature'.format(obj))
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def signature(obj):
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'''Get a signature object for the passed callable.'''
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return _signature_internal(obj)
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class _void:
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'''A private marker - used in Parameter & Signature'''
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@ -2417,15 +2444,7 @@ class Signature:
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@classmethod
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def from_builtin(cls, func):
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if not _signature_is_builtin(func):
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raise TypeError("{!r} is not a Python builtin "
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"function".format(func))
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s = getattr(func, "__text_signature__", None)
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if not s:
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raise ValueError("no signature found for builtin {!r}".format(func))
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return _signature_fromstr(cls, func, s)
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return _signature_from_builtin(cls, func)
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@property
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def parameters(self):
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@ -577,6 +577,46 @@ class TestClassesAndFunctions(unittest.TestCase):
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kwonlyargs_e=['arg'],
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formatted='(*, arg)')
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def test_argspec_api_ignores_wrapped(self):
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# Issue 20684: low level introspection API must ignore __wrapped__
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@functools.wraps(mod.spam)
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def ham(x, y):
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pass
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# Basic check
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self.assertArgSpecEquals(ham, ['x', 'y'], formatted='(x, y)')
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self.assertFullArgSpecEquals(ham, ['x', 'y'], formatted='(x, y)')
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self.assertFullArgSpecEquals(functools.partial(ham),
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['x', 'y'], formatted='(x, y)')
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# Other variants
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def check_method(f):
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self.assertArgSpecEquals(f, ['self', 'x', 'y'],
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formatted='(self, x, y)')
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class C:
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@functools.wraps(mod.spam)
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def ham(self, x, y):
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pass
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pham = functools.partialmethod(ham)
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@functools.wraps(mod.spam)
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def __call__(self, x, y):
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pass
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check_method(C())
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check_method(C.ham)
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check_method(C().ham)
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check_method(C.pham)
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check_method(C().pham)
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class C_new:
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@functools.wraps(mod.spam)
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def __new__(self, x, y):
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pass
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check_method(C_new)
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class C_init:
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@functools.wraps(mod.spam)
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def __init__(self, x, y):
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pass
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check_method(C_init)
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def test_getfullargspec_signature_attr(self):
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def test():
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pass
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@ -66,6 +66,10 @@ Library
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loop.set_exception_handler(), loop.default_exception_handler(), and
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loop.call_exception_handler().
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- Issue #20684: Fix inspect.getfullargspec() to not to follow __wrapped__
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chains. Make its behaviour consistent with bound methods first argument.
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Patch by Nick Coghlan and Yury Selivanov.
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Tests
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-----
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