Issue 20691: Add follow_wrapped arg to inspect.signature/from_callable.

2 files changed, 19 insertions, 6 deletions

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 13d0c7b..9ad55a9 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -2664,9 +2664,10 @@ class Signature:
         return _signature_from_builtin(cls, func)
 
     @classmethod
-    def from_callable(cls, obj):
+    def from_callable(cls, obj, *, follow_wrapped=True):
         """Constructs Signature for the given callable object."""
-        return _signature_from_callable(obj, sigcls=cls)
+        return _signature_from_callable(obj, sigcls=cls,
+                                        follow_wrapper_chains=follow_wrapped)
 
     @property
     def parameters(self):
@@ -2915,9 +2916,9 @@ class Signature:
         return rendered
 
 
-def signature(obj):
+def signature(obj, *, follow_wrapped=True):
     """Get a signature object for the passed callable."""
-    return Signature.from_callable(obj)
+    return Signature.from_callable(obj, follow_wrapped=follow_wrapped)
 
 
 def _main():
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 92bc096..8d11783 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -1735,8 +1735,8 @@ class MyParameter(inspect.Parameter):
 
 class TestSignatureObject(unittest.TestCase):
     @staticmethod
-    def signature(func):
-        sig = inspect.signature(func)
+    def signature(func, **kw):
+        sig = inspect.signature(func, **kw)
         return (tuple((param.name,
                        (... if param.default is param.empty else param.default),
                        (... if param.annotation is param.empty
@@ -1956,6 +1956,11 @@ class TestSignatureObject(unittest.TestCase):
         self.assertEqual(inspect.signature(func),
                          inspect.signature(decorated_func))
 
+        def wrapper_like(*args, **kwargs) -> int: pass
+        self.assertEqual(inspect.signature(decorated_func,
+                                           follow_wrapped=False),
+                         inspect.signature(wrapper_like))
+
     @cpython_only
     def test_signature_on_builtins_no_signature(self):
         import _testcapi
@@ -2384,6 +2389,13 @@ class TestSignatureObject(unittest.TestCase):
                            ('b', ..., ..., "positional_or_keyword")),
                           ...))
 
+        self.assertEqual(self.signature(Foo.bar, follow_wrapped=False),
+                         ((('args', ..., ..., "var_positional"),
+                           ('kwargs', ..., ..., "var_keyword")),
+                          ...)) # functools.wraps will copy __annotations__
+                                # from "func" to "wrapper", hence no
+                                # return_annotation
+
         # Test that we handle method wrappers correctly
         def decorator(func):
             @functools.wraps(func)