[Python-checkins] bpo-36798: Updating f-string docs for := use case (GH-13107)

[Guido van Rossum]

https://github.com/python/cpython/commit/ae2c32f32b61f3b141ba4b0b1ad71781d2f9a1a1
commit: ae2c32f32b61f3b141ba4b0b1ad71781d2f9a1a1
branch: master
author: Logan Jones <loganasherjones at gmail.com>
committer: Guido van Rossum <guido at python.org>
date: 2019-05-06T11:32:44-05:00
summary:

bpo-36798: Updating f-string docs for := use case (GH-13107)

files:
M Doc/reference/lexical_analysis.rst

diff --git a/Doc/reference/lexical_analysis.rst b/Doc/reference/lexical_analysis.rst
index fb04ccc839aa..13adc1a2e433 100644
--- a/Doc/reference/lexical_analysis.rst
+++ b/Doc/reference/lexical_analysis.rst
@@ -680,11 +680,12 @@ with a closing curly bracket ``'}'``.
 
 Expressions in formatted string literals are treated like regular
 Python expressions surrounded by parentheses, with a few exceptions.
-An empty expression is not allowed, and a :keyword:`lambda` expression
-must be surrounded by explicit parentheses.  Replacement expressions
-can contain line breaks (e.g. in triple-quoted strings), but they
-cannot contain comments.  Each expression is evaluated in the context
-where the formatted string literal appears, in order from left to right.
+An empty expression is not allowed, and both :keyword:`lambda`  and
+assignment expressions ``:=`` must be surrounded by explicit parentheses.
+Replacement expressions can contain line breaks (e.g. in triple-quoted
+strings), but they cannot contain comments.  Each expression is evaluated
+in the context where the formatted string literal appears, in order from
+left to right.
 
 If a conversion is specified, the result of evaluating the expression
 is converted before formatting.  Conversion ``'!s'`` calls :func:`str` on