bpo-30485: Change the prefix for defining the default namespace in ElementPath from None to '' since there is existing code that uses that and it's more convenient to have an all-string-keys dict (e.g. when sorting items etc.). (#12860)

2 files changed, 3 insertions, 7 deletions

diff --git a/Lib/test/test_xml_etree.py b/Lib/test/test_xml_etree.py
index f5b118b..14ce32a 100644
--- a/Lib/test/test_xml_etree.py
+++ b/Lib/test/test_xml_etree.py
@@ -2463,7 +2463,7 @@ class ElementFindTest(unittest.TestCase):
         nsmap = {'xx': 'Y'}
         self.assertEqual(len(root.findall(".//xx:b", namespaces=nsmap)), 1)
         self.assertEqual(len(root.findall(".//b", namespaces=nsmap)), 2)
-        nsmap = {'xx': 'X', None: 'Y'}
+        nsmap = {'xx': 'X', '': 'Y'}
         self.assertEqual(len(root.findall(".//xx:b", namespaces=nsmap)), 2)
         self.assertEqual(len(root.findall(".//b", namespaces=nsmap)), 1)
 
diff --git a/Lib/xml/etree/ElementPath.py b/Lib/xml/etree/ElementPath.py
index 4d231a7..b670d58 100644
--- a/Lib/xml/etree/ElementPath.py
+++ b/Lib/xml/etree/ElementPath.py
@@ -71,7 +71,7 @@ xpath_tokenizer_re = re.compile(
     )
 
 def xpath_tokenizer(pattern, namespaces=None):
-    default_namespace = namespaces.get(None) if namespaces else None
+    default_namespace = namespaces.get('') if namespaces else None
     for token in xpath_tokenizer_re.findall(pattern):
         tag = token[1]
         if tag and tag[0] != "{":
@@ -275,11 +275,7 @@ def iterfind(elem, path, namespaces=None):
 
     cache_key = (path,)
     if namespaces:
-        if None in namespaces:
-            cache_key += (namespaces[None],) + tuple(sorted(
-                item for item in namespaces.items() if item[0] is not None))
-        else:
-            cache_key += tuple(sorted(namespaces.items()))
+        cache_key += tuple(sorted(namespaces.items()))
 
     try:
         selector = _cache[cache_key]