From 9bb957dac6882b0eb076a23274ab848d93611e32 Mon Sep 17 00:00:00 2001
From: Jolbas <39026960+Jolbas@users.noreply.github.com>
Date: Sun, 25 Sep 2022 16:11:36 +0200
Subject: [PATCH] fix: restore pre-3.1 behaviour converting fields to named
 tuples attributes

Let more valid identifiers through _as_python_identifier(). Also 2.5x faster if no change is needed

Close #386
---
 psycopg/psycopg/_encodings.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/psycopg/psycopg/_encodings.py b/psycopg/psycopg/_encodings.py
index d293949e3..b1b21267c 100644
--- a/psycopg/psycopg/_encodings.py
+++ b/psycopg/psycopg/_encodings.py
@@ -146,10 +146,13 @@ def _as_python_identifier(s: str, prefix: str = "f") -> str:
     Replace all non-valid chars with '_' and prefix the value with *prefix* if
     the first letter is an '_'.
     """
-    s = _re_clean.sub("_", s)
-    # Python identifier cannot start with numbers, namedtuple fields
-    # cannot start with underscore. So...
-    if s[0] == "_" or "0" <= s[0] <= "9":
+    if not s.isidentifier():
+        if s[0] in "1234567890":
+            s = prefix + s
+        if not s.isidentifier():
+            s = _re_clean.sub("_", s)
+    # namedtuple fields cannot start with underscore. So...
+    if s[0] == "_":
         s = prefix + s
     return s
 
-- 
2.47.2