[Python-checkins] bpo-41621: Document defaultdict's default_factory parameter (GH-21945)

[terryjreedy]

https://github.com/python/cpython/commit/d1ae57027fc39ff60dcfc1b63881400e5ca3ce56
commit: d1ae57027fc39ff60dcfc1b63881400e5ca3ce56
branch: main
author: Dennis Sweeney <36520290+sweeneyde at users.noreply.github.com>
committer: terryjreedy <tjreedy at udel.edu>
date: 2021-06-22T10:19:24-04:00
summary:

bpo-41621: Document defaultdict's default_factory parameter (GH-21945)

It defaults to None and is positional only.

files:
A Misc/NEWS.d/next/Documentation/2020-08-24-13-35-04.bpo-41621.nqaw9G.rst
M Doc/library/collections.rst
M Modules/_collectionsmodule.c

diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 94166ec6c754a..a63090414d439 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -707,9 +707,9 @@ stack manipulations such as ``dup``, ``drop``, ``swap``, ``over``, ``pick``,
 :class:`defaultdict` objects
 ----------------------------
 
-.. class:: defaultdict([default_factory[, ...]])
+.. class:: defaultdict(default_factory=None, /, [...])
 
-    Returns a new dictionary-like object.  :class:`defaultdict` is a subclass of the
+    Return a new dictionary-like object.  :class:`defaultdict` is a subclass of the
     built-in :class:`dict` class.  It overrides one method and adds one writable
     instance variable.  The remaining functionality is the same as for the
     :class:`dict` class and is not documented here.
diff --git a/Misc/NEWS.d/next/Documentation/2020-08-24-13-35-04.bpo-41621.nqaw9G.rst b/Misc/NEWS.d/next/Documentation/2020-08-24-13-35-04.bpo-41621.nqaw9G.rst
new file mode 100644
index 0000000000000..bd193d9163073
--- /dev/null
+++ b/Misc/NEWS.d/next/Documentation/2020-08-24-13-35-04.bpo-41621.nqaw9G.rst
@@ -0,0 +1 @@
+Document that :class:`collections.defaultdict` parameter ``default_factory`` defaults to None and is positional-only.
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 79c6b5752afa2..57e3464145be6 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -2241,7 +2241,7 @@ defdict_init(PyObject *self, PyObject *args, PyObject *kwds)
 }
 
 PyDoc_STRVAR(defdict_doc,
-"defaultdict(default_factory[, ...]) --> dict with default factory\n\
+"defaultdict(default_factory=None, /, [...]) --> dict with default factory\n\
 \n\
 The default factory is called without arguments to produce\n\
 a new value when a key is not present, in __getitem__ only.\n\