PEP 622: drop restriction on ._ an _.a

pep-0622.rst

@@ -317,15 +317,6 @@ adding it is not prohibited, so ``.Color.BLACK`` is the same as ``Color.BLACK``.
 See `rejected ideas`_ for other syntactic alternatives that were considered
 for constant value pattern.
 
-The initial name must not be ``_`` because ``_`` has a special meaning in
-pattern matching, so these are invalid::
-
-    case ._: ...
-    case _.a: ...
-
-However, ``a._`` is legal and loads the attribute with name ``_`` of the
-object ``a`` as usual.
-
 
 .. _sequence_pattern:
 
@@ -1404,6 +1395,24 @@ provide the *values* for all positional arguments at once.  And there
 seems to be no practical need for it, so it was scrapped.  (It could
 easily be added at a later stage if a need arises.)
 
+Disallow ``._`` and ``_.a`` in constant value patterns
+------------------------------------------------------
+
+The first public draft said that the initial name in a constant value
+pattern must not be ``_`` because ``_`` has a special meaning in
+pattern matching, so these would be invalid::
+
+    case ._: ...
+    case _.a: ...
+
+(However, ``a._`` would be legal and load the attribute with name
+``_`` of the object ``a`` as usual.)
+
+There was some pushback against this on python-dev (some people have a
+legitimate use for ``_`` as an important global variable, esp. in
+i18n) and the only reason for this prohibition was to prevent some
+user confusion.  But it's not the hill to die on.
+
 
 .. _deferred ideas: