PEP 572: Alter the definition of assignment through SLNBs

pep-0572.rst

@@ -38,13 +38,17 @@ and ``NAME`` is a simple name.
 
 The value of such a named expression is the same as the incorporated
 expression, with the additional side-effect that NAME is bound to that
-value for the remainder of the current statement.
+value in all retrievals for the remainder of the current statement.
 
 Just as function-local names shadow global names for the scope of the
 function, statement-local names shadow other names for that statement.
 They can also shadow each other, though actually doing this should be
 strongly discouraged in style guides.
 
+Assignment to statement-local names is ONLY through this syntax. Regular
+assignment to the same name will remove the statement-local name and
+affect the name in the surrounding scope (function, class, or module).
+
 Execution order and its consequences
 ------------------------------------
 
@@ -57,7 +61,7 @@ expectations. Some examples::
     a = (1 as y)
     print(y) # NameError
 
-    # For the evil people who write a=a++ in C
+    # The assignment ignores the SLNB - this adds one to 'a'
     a = (a + 1 as a)
 
     # Compound statements usually enclose everything...
@@ -259,6 +263,8 @@ Discrepancies in the current implementation
    shadow any other names from the same function); as an alternative, they
    could simply never appear, even when in scope.
 
+3. Assigning 'through' a SLNB is not implemented yet.
+
 
 References
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