diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index 1530775839bb6c..de1e717e56deb1 100644 --- 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 ef13d55e756bd4..c2edc3f0975939 100644 --- 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 index 00000000000000..6698ed607ca0ea --- /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.