bpo-39879: Update datamodel docs to include dict ordering (GH-19006)

Co-authored-by: furkanonder <furkantahaonder@gmail.com>
(cherry picked from commit 59c644eaa72b0cc48302f59d66852c4ea8332eba)

Co-authored-by: Lahfa Samy <lahfa121999@gmail.com>

diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index 1530775839bb6cd481f5daef5b89ddec275c4a28..de1e717e56deb176a28c5043d9394ad54119b6d9 100644 (file)
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -420,6 +420,11 @@ Mappings
       equal (e.g., ``1`` and ``1.0``) then they can be used interchangeably to index
       the same dictionary entry.
 
+      Dictionaries preserve insertion order, meaning that keys will be produced
+      in the same order they were added sequentially over the dictionary.
+      Replacing an existing key does not change the order, however removing a key
+      and re-inserting it will add it to the end instead of keeping its old place.
+
       Dictionaries are mutable; they can be created by the ``{...}`` notation (see
       section :ref:`dict`).
 
@@ -431,6 +436,11 @@ Mappings
       additional examples of mapping types, as does the :mod:`collections`
       module.
 
+      .. versionchanged:: 3.7
+         Dictionaries did not preserve insertion order in versions of Python before 3.6.
+         In CPython 3.6, insertion order was preserved, but it was considered
+         an implementation detail at that time rather than a language guarantee.
+
 Callable types
    .. index::
       object: callable

diff --git a/Misc/ACKS b/Misc/ACKS
index ef13d55e756bd4b0a8107d482e7601b0a4402bcb..c2edc3f0975939ebfb67702381a52dda96863e1e 100644 (file)
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -38,6 +38,7 @@ Ray Allen
 Billy G. Allie
 Jamiel Almeida
 Kevin Altis
+Samy Lahfa
 Skyler Leigh Amador
 Joe Amenta
 Rose Ames

diff --git a/Misc/NEWS.d/next/Documentation/2020-03-16-18-12-02.bpo-39879.CnQ7Cv.rst b/Misc/NEWS.d/next/Documentation/2020-03-16-18-12-02.bpo-39879.CnQ7Cv.rst
new file mode 100644 (file)
index 0000000..6698ed6
--- /dev/null
+++ b/Misc/NEWS.d/next/Documentation/2020-03-16-18-12-02.bpo-39879.CnQ7Cv.rst
@@ -0,0 +1,2 @@
+Updated :ref:`datamodel` docs to include :func:`dict` insertion order preservation.
+Patch by Furkan Onder and Samy Lahfa.