bpo-34149: Behavior of the min/max with key=None (GH-8328)
Improve consistency with the signature for sorted(), heapq.nsmallest(), heapq.nlargest(), and itertools.groupby().
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 68a5dce..e52b090 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -869,6 +869,9 @@
.. versionadded:: 3.4
The *default* keyword-only argument.
+ .. versionchanged:: 3.8
+ The *key* can be ``None``.
+
.. _func-memoryview:
.. function:: memoryview(obj)
@@ -903,6 +906,9 @@
.. versionadded:: 3.4
The *default* keyword-only argument.
+ .. versionchanged:: 3.8
+ The *key* can be ``None``.
+
.. function:: next(iterator[, default])
diff --git a/Lib/heapq.py b/Lib/heapq.py
index b31f418..0e3555c 100644
--- a/Lib/heapq.py
+++ b/Lib/heapq.py
@@ -468,10 +468,7 @@
if n == 1:
it = iter(iterable)
sentinel = object()
- if key is None:
- result = min(it, default=sentinel)
- else:
- result = min(it, default=sentinel, key=key)
+ result = min(it, default=sentinel, key=key)
return [] if result is sentinel else [result]
# When n>=size, it's faster to use sorted()
@@ -531,10 +528,7 @@
if n == 1:
it = iter(iterable)
sentinel = object()
- if key is None:
- result = max(it, default=sentinel)
- else:
- result = max(it, default=sentinel, key=key)
+ result = max(it, default=sentinel, key=key)
return [] if result is sentinel else [result]
# When n>=size, it's faster to use sorted()
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 8f91bc9..233c579 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -905,6 +905,8 @@
self.assertEqual(max((), default=1, key=neg), 1)
self.assertEqual(max((1, 2), default=3, key=neg), 1)
+ self.assertEqual(max((1, 2), key=None), 2)
+
data = [random.randrange(200) for i in range(100)]
keys = dict((elem, random.randrange(50)) for elem in data)
f = keys.__getitem__
@@ -957,6 +959,8 @@
self.assertEqual(min((), default=1, key=neg), 1)
self.assertEqual(min((1, 2), default=1, key=neg), 2)
+ self.assertEqual(min((1, 2), key=None), 1)
+
data = [random.randrange(200) for i in range(100)]
keys = dict((elem, random.randrange(50)) for elem in data)
f = keys.__getitem__
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-07-23-21-49-05.bpo-34149.WSV-_g.rst b/Misc/NEWS.d/next/Core and Builtins/2018-07-23-21-49-05.bpo-34149.WSV-_g.rst
new file mode 100644
index 0000000..9672bcf
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-07-23-21-49-05.bpo-34149.WSV-_g.rst
@@ -0,0 +1 @@
+Fix min and max functions to get default behavior when key is None.
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 88a4bf9..7bb5687 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1639,6 +1639,10 @@
return NULL;
}
+ if (keyfunc == Py_None) {
+ keyfunc = NULL;
+ }
+
maxitem = NULL; /* the result */
maxval = NULL; /* the value associated with the result */
while (( item = PyIter_Next(it) )) {