Issue #8814: function annotations (the `__annotations__` attribute)

are now included in the set of attributes copied by default by
functools.wraps and functools.update_wrapper.  Patch by Terrence Cole.

diff --git a/Doc/library/functools.rst b/Doc/library/functools.rst
index c6f5870745d3279b37c7ebaa3b96fb412c586401..39b0e7b9b2cf924adf1895203a654e81effdbcea 100644 (file)
--- a/Doc/library/functools.rst
+++ b/Doc/library/functools.rst
@@ -165,9 +165,9 @@ The :mod:`functools` module defines the following functions:
    attributes of the wrapper function are updated with the corresponding attributes
    from the original function. The default values for these arguments are the
    module level constants *WRAPPER_ASSIGNMENTS* (which assigns to the wrapper
-   function's *__name__*, *__module__* and *__doc__*, the documentation string) and
-   *WRAPPER_UPDATES* (which updates the wrapper function's *__dict__*, i.e. the
-   instance dictionary).
+   function's *__name__*, *__module__*, *__annotations__* and *__doc__*, the
+   documentation string) and *WRAPPER_UPDATES* (which updates the wrapper
+   function's *__dict__*, i.e. the instance dictionary).
 
    The main intended use for this function is in :term:`decorator` functions which
    wrap the decorated function and return the wrapper. If the wrapper function is

diff --git a/Lib/functools.py b/Lib/functools.py
index 863706d40e3907c9fcc31c44e0b0b33070d541b7..e2440700bcd97051b71151d647d8df4e8cd54454 100644 (file)
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -19,7 +19,7 @@ from operator import itemgetter
 # update_wrapper() and wraps() are tools to help write
 # wrapper functions that can handle naive introspection
 
-WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__')
+WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__', '__annotations__')
 WRAPPER_UPDATES = ('__dict__',)
 def update_wrapper(wrapper,
                    wrapped,
@@ -37,7 +37,8 @@ def update_wrapper(wrapper,
        function (defaults to functools.WRAPPER_UPDATES)
     """
     for attr in assigned:
-        setattr(wrapper, attr, getattr(wrapped, attr))
+        if hasattr(wrapped, attr):
+            setattr(wrapper, attr, getattr(wrapped, attr))
     for attr in updated:
         getattr(wrapper, attr).update(getattr(wrapped, attr, {}))
     # Return the wrapper so this can be used as a decorator via partial()

diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index a02d37ce8ae9a2593eb969ce0354e907989de069..70a8ad62ec8a7e6d47f864b9f46d230106ff1621 100644 (file)
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -182,11 +182,11 @@ class TestUpdateWrapper(unittest.TestCase):
                 self.assertTrue(wrapped_attr[key] is wrapper_attr[key])
 
     def _default_update(self):
-        def f():
+        def f(a:'This is a new annotation'):
             """This is a test"""
             pass
         f.attr = 'This is also a test'
-        def wrapper():
+        def wrapper(b:'This is the prior annotation'):
             pass
         functools.update_wrapper(wrapper, f)
         return wrapper, f
@@ -196,6 +196,8 @@ class TestUpdateWrapper(unittest.TestCase):
         self.check_wrapper(wrapper, f)
         self.assertEqual(wrapper.__name__, 'f')
         self.assertEqual(wrapper.attr, 'This is also a test')
+        self.assertEqual(wrapper.__annotations__['a'], 'This is a new annotation')
+        self.assertNotIn('b', wrapper.__annotations__)
 
     @unittest.skipIf(sys.flags.optimize >= 2,
                      "Docstrings are omitted with -O2 and above")
@@ -214,6 +216,7 @@ class TestUpdateWrapper(unittest.TestCase):
         self.check_wrapper(wrapper, f, (), ())
         self.assertEqual(wrapper.__name__, 'wrapper')
         self.assertEqual(wrapper.__doc__, None)
+        self.assertEqual(wrapper.__annotations__, {})
         self.assertFalse(hasattr(wrapper, 'attr'))
 
     def test_selective_update(self):
@@ -240,6 +243,7 @@ class TestUpdateWrapper(unittest.TestCase):
         functools.update_wrapper(wrapper, max)
         self.assertEqual(wrapper.__name__, 'max')
         self.assertTrue(wrapper.__doc__.startswith('max('))
+        self.assertEqual(wrapper.__annotations__, {})
 
 class TestWraps(TestUpdateWrapper):
 

diff --git a/Misc/ACKS b/Misc/ACKS
index e7ec4caef2dfbed3fe07a082fc08878dae5fee74..41d314e19642ee2cce9c1949cc4d9c6b2e2a0db6 100644 (file)
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -154,6 +154,7 @@ Steve Clift
 Nick Coghlan
 Josh Cogliati
 Dave Cole
+Terrence Cole
 Benjamin Collar
 Jeffery Collins
 Robert Collins

diff --git a/Misc/NEWS b/Misc/NEWS
index 22f1d0fd1de69fbe38f776468945432597541934..6bc3e5cb949b4bf4618b1eef3fdfdc1ccb5b81d5 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -37,6 +37,10 @@ Extensions
 Library
 -------
 
+- Issue #8814: function annotations (the ``__annotations__`` attribute)
+  are now included in the set of attributes copied by default by
+  functools.wraps and functools.update_wrapper.  Patch by Terrence Cole.
+
 - Issue #2944: asyncore doesn't handle connection refused correctly.
 
 - Issue #4184: Private attributes on smtpd.SMTPChannel made public and