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[3.8] bpo-35224: Add What's new entry for evaluation order in dict comprehensions (GH-14319) #14361

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miss-islington merged 1 commit into from
Jun 25, 2019
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[3.8] bpo-35224: Add What's new entry for evaluation order in dict comprehensions (GH-14319) #14361

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8 changes: 8 additions & 0 deletions Doc/whatsnew/3.8.rst
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Expand Up @@ -349,6 +349,9 @@ Other Language Changes
is ``-1``, and a suitable power of that inverse for other negative exponents.
(Contributed by Mark Dickinson in :issue:`36027`.)

* When dictionary comprehensions are evaluated, the key is now evaluated before
the value, as proposed by :pep:`572`.


New Modules
===========
Expand Down Expand Up @@ -1499,6 +1502,11 @@ CPython bytecode changes
when awaiting a next item in an :keyword:`async for` loop.
(Contributed by Serhiy Storchaka in :issue:`33041`.)

* The :opcode:`MAP_ADD` now expects the value as the first element in the
stack and the key as the second element. This change was made so the key
is always evaluated before the value in dictionary comprehensions, as
porposed by :pep:`572`. (Contributed by Jörn Heissler in :issue:`35224`.)


Demos and Tools
---------------
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