[Python-checkins] cpython: inspect.Signature: Make from_builtin to raise an exception if no signature can

Wed Jan 29 16:46:28 CET 2014

http://hg.python.org/cpython/rev/9433b380ad33
changeset: 88809:9433b380ad33
parent: 88807:483096ef1cf6
user: Yury Selivanov <yselivanov at sprymix.com>
date: Wed Jan 29 10:46:14 2014 -0500
summary:
 inspect.Signature: Make from_builtin to raise an exception if no signature can
be provided #20422
files:
 Lib/inspect.py | 30 ++++++++++++++++++---------
 Lib/test/test_inspect.py | 4 +++
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/Lib/inspect.py b/Lib/inspect.py
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -1514,18 +1514,24 @@
 return sig.replace(parameters=params)
 
 
+def _signature_is_builtin(obj):
+ # Internal helper to test if `obj` is a callable that might
+ # support Argument Clinic's __text_signature__ protocol.
+ return (isinstance(obj, _NonUserDefinedCallables) or
+ ismethoddescriptor(obj) or
+ # Can't test 'isinstance(type)' here, as it would
+ # also be True for regular python classes
+ obj in (type, object))
+
+
 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, _NonUserDefinedCallables) or
- ismethoddescriptor(obj) or
- isinstance(obj, type)):
- sig = Signature.from_builtin(obj)
- if sig:
- return sig
+ if _signature_is_builtin(obj):
+ return Signature.from_builtin(obj)
 
 if isinstance(obj, types.MethodType):
 # In this case we skip the first parameter of the underlying
@@ -2017,9 +2023,13 @@
 
 @classmethod
 def from_builtin(cls, func):
+ if not _signature_is_builtin(func):
+ raise TypeError("{!r} is not a Python builtin "
+ "function".format(func))
+
 s = getattr(func, "__text_signature__", None)
 if not s:
- return None
+ raise ValueError("no signature found for builtin {!r}".format(func))
 
 Parameter = cls._parameter_cls
 
@@ -2038,9 +2048,10 @@
 try:
 module = ast.parse(s)
 except SyntaxError:
- return None
+ module = None
+
 if not isinstance(module, ast.Module):
- return None
+ raise ValueError("{!r} builtin has invalid signature".format(func))
 
 f = module.body[0]
 
@@ -2149,7 +2160,6 @@
 
 return cls(parameters, return_annotation=cls.empty)
 
-
 @property
 def parameters(self):
 return self._parameters
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -1667,6 +1667,10 @@
 with self.assertRaisesRegex(TypeError, 'is not a Python function'):
 inspect.Signature.from_function(42)
 
+ def test_signature_from_builtin_errors(self):
+ with self.assertRaisesRegex(TypeError, 'is not a Python builtin'):
+ inspect.Signature.from_builtin(42)
+
 def test_signature_on_method(self):
 class Test:
 def __init__(*args):
-- 
Repository URL: http://hg.python.org/cpython
