commit d1e768a67707bf7bb426c1537e1a764e89eaff78
author Raymond Hettinger <rhettinger@users.noreply.github.com> Mon Mar 25 13:01:13 2019 -0700
committer GitHub <noreply@github.com> Mon Mar 25 13:01:13 2019 -0700
tree eba1dc9c8a257e8c9fec36cef006eb06498d54ee
parent 713a8ae7926472b02ee1a394633eb54aaa7912d1

bpo-36326: Let inspect.getdoc() find docstrings for __slots__ (GH-12498)

Lib/inspect.py

diff --git a/Lib/inspect.py b/Lib/inspect.py
index b8a1422..8c398bd 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -582,9 +582,12 @@
         cls = obj.__objclass__
         if getattr(cls, name) is not obj:
             return None
+        if ismemberdescriptor(obj):
+            slots = getattr(cls, '__slots__', None)
+            if isinstance(slots, dict) and name in slots:
+                return slots[name]
     else:
         return None
-
     for base in cls.__mro__:
         try:
             doc = getattr(base, name).__doc__

Lib/statistics.py

diff --git a/Lib/statistics.py b/Lib/statistics.py
index e5a6246..bd8a6f9 100644
--- a/Lib/statistics.py
+++ b/Lib/statistics.py
@@ -709,7 +709,8 @@
     # https://en.wikipedia.org/wiki/Normal_distribution
     # https://en.wikipedia.org/wiki/Variance#Properties
 
-    __slots__ = ('mu', 'sigma')
+    __slots__ = {'mu': 'Arithmetic mean of a normal distribution',
+                 'sigma': 'Standard deviation of a normal distribution'}
 
     def __init__(self, mu=0.0, sigma=1.0):
         'NormalDist where mu is the mean and sigma is the standard deviation.'

Lib/test/test_inspect.py

diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index b9072e0..bc675aa 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -375,6 +375,11 @@
         self.assertEqual(inspect.getsource(obj),
                          self.sourcerange(top, bottom))
 
+class SlotUser:
+    'Docstrings for __slots__'
+    __slots__ = {'power': 'measured in kilowatts',
+                 'distance': 'measured in kilometers'}
+
 class TestRetrievingSourceCode(GetSourceBase):
     fodderModule = mod
 
@@ -429,6 +434,10 @@
                          'A longer,\n\nindented\n\ndocstring.')
         self.assertEqual(inspect.getdoc(git.abuse),
                          'Another\n\ndocstring\n\ncontaining\n\ntabs')
+        self.assertEqual(inspect.getdoc(SlotUser.power),
+                         'measured in kilowatts')
+        self.assertEqual(inspect.getdoc(SlotUser.distance),
+                         'measured in kilometers')
 
     @unittest.skipIf(sys.flags.optimize >= 2,
                      "Docstrings are omitted with -O2 and above")

Lib/test/test_statistics.py

diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py
index 485ffe2..7f7839d 100644
--- a/Lib/test/test_statistics.py
+++ b/Lib/test/test_statistics.py
@@ -2051,7 +2051,7 @@
         nd = statistics.NormalDist(300, 23)
         with self.assertRaises(TypeError):
             vars(nd)
-        self.assertEqual(nd.__slots__, ('mu', 'sigma'))
+        self.assertEqual(tuple(nd.__slots__), ('mu', 'sigma'))
 
     def test_instantiation_and_attributes(self):
         nd = statistics.NormalDist(500, 17)