gh-141510: Use frozendict in the stdlib

Co-authored-by: Donghee Na <donghee.na@python.org>
vstinner · Mar 6, 2026 · Feb 17, 2026 · Feb 17, 2026 · Feb 17, 2026 · Feb 18, 2026
commit 300cf8f0bbf45b8919e9a450719d1d89a8b231dc
@@ -170,7 +170,7 @@ def _lt_from_ge(self, other):
         return op_result
     return not op_result
 
-_convert = {
+_convert = frozendict({
     '__lt__': [('__gt__', _gt_from_lt),
                ('__le__', _le_from_lt),
                ('__ge__', _ge_from_lt)],
@@ -183,7 +183,7 @@ def _lt_from_ge(self, other):
     '__ge__': [('__le__', _le_from_ge),
                ('__gt__', _gt_from_ge),
                ('__lt__', _lt_from_ge)]
-}
+})
 
 def total_ordering(cls):
     """Class decorator that fills in missing ordering methods"""

@@ -111,8 +111,9 @@ def _error(value):
     ('+', '-'),
     ('*', '/', '%'),
 )
-_binary_ops = {op: i for i, ops in enumerate(_binary_ops, 1) for op in ops}
-_c2py_ops = {'||': 'or', '&&': 'and', '/': '//'}
+_binary_ops = frozendict({op: i for i, ops in enumerate(_binary_ops, 1)
+                          for op in ops})
+_c2py_ops = frozendict({'||': 'or', '&&': 'and', '/': '//'})
 
 
 def _parse(tokens, priority=-1):

diff --git a/Lib/json/decoder.py b/Lib/json/decoder.py
@@ -43,11 +43,11 @@ def __reduce__(self):
         return self.__class__, (self.msg, self.doc, self.pos)
 
 
-_CONSTANTS = {
+_CONSTANTS = frozendict({
     '-Infinity': NegInf,
     'Infinity': PosInf,
     'NaN': NaN,
-}
+})
 
 
 HEXDIGITS = re.compile(r'[0-9A-Fa-f]{4}', FLAGS)

diff --git a/Lib/json/tool.py b/Lib/json/tool.py
@@ -22,13 +22,13 @@
     (?P<null>null)
 ''', re.VERBOSE)
 
-_group_to_theme_color = {
+_group_to_theme_color = frozendict({
     "key": "definition",
     "string": "string",
     "number": "number",
     "boolean": "keyword",
     "null": "keyword",
-}
+})
 
 
 def _colorize_json(json_str, theme):

diff --git a/Lib/opcode.py b/Lib/opcode.py
@@ -46,81 +46,81 @@
 
 hascompare = [opmap["COMPARE_OP"]]
 
-_cache_format = {
-    "LOAD_GLOBAL": {
+_cache_format = frozendict(
+    LOAD_GLOBAL={
         "counter": 1,
         "index": 1,
         "module_keys_version": 1,
         "builtin_keys_version": 1,
     },
-    "BINARY_OP": {
+    BINARY_OP={
         "counter": 1,
         "descr": 4,
     },
-    "UNPACK_SEQUENCE": {
+    UNPACK_SEQUENCE={
         "counter": 1,
     },
-    "COMPARE_OP": {
+    COMPARE_OP={
         "counter": 1,
     },
-    "CONTAINS_OP": {
+    CONTAINS_OP={
         "counter": 1,
     },
-    "FOR_ITER": {
+    FOR_ITER={
         "counter": 1,
     },
-    "LOAD_SUPER_ATTR": {
+    LOAD_SUPER_ATTR={
         "counter": 1,
     },
-    "LOAD_ATTR": {
+    LOAD_ATTR={
         "counter": 1,
         "version": 2,
         "keys_version": 2,
         "descr": 4,
     },
-    "STORE_ATTR": {
+    STORE_ATTR={
         "counter": 1,
         "version": 2,
         "index": 1,
     },
-    "CALL": {
+    CALL={
         "counter": 1,
         "func_version": 2,
     },
-    "CALL_KW": {
+    CALL_KW={
         "counter": 1,
         "func_version": 2,
     },
-    "CALL_FUNCTION_EX": {
+    CALL_FUNCTION_EX={
         "counter": 1,
     },
-    "STORE_SUBSCR": {
+    STORE_SUBSCR={
         "counter": 1,
     },
-    "SEND": {
+    SEND={
         "counter": 1,
     },
-    "JUMP_BACKWARD": {
+    JUMP_BACKWARD={
         "counter": 1,
     },
-    "TO_BOOL": {
+    TO_BOOL={
         "counter": 1,
         "version": 2,
     },
-    "POP_JUMP_IF_TRUE": {
+    POP_JUMP_IF_TRUE={
         "counter": 1,
     },
-    "POP_JUMP_IF_FALSE": {
+    POP_JUMP_IF_FALSE={
         "counter": 1,
     },
-    "POP_JUMP_IF_NONE": {
+    POP_JUMP_IF_NONE={
         "counter": 1,
     },
-    "POP_JUMP_IF_NOT_NONE": {
+    POP_JUMP_IF_NOT_NONE={
         "counter": 1,
     },
-}
+)
 
-_inline_cache_entries = {
+_inline_cache_entries = frozendict({
     name : sum(value.values()) for (name, value) in _cache_format.items()
-}
+})
diff --git a/Lib/optparse.py b/Lib/optparse.py
@@ -407,10 +407,12 @@ def _parse_num(val, type):
 def _parse_int(val):
     return _parse_num(val, int)
 
-_builtin_cvt = { "int" : (_parse_int, _("integer")),
-                 "long" : (_parse_int, _("integer")),
-                 "float" : (float, _("floating-point")),
-                 "complex" : (complex, _("complex")) }
+_builtin_cvt = frozendict({
+    "int": (_parse_int, _("integer")),
+    "long": (_parse_int, _("integer")),
+    "float": (float, _("floating-point")),
+    "complex": (complex, _("complex")),
+})
 
 def check_builtin(option, opt, value):
     (cvt, what) = _builtin_cvt[option.type]

diff --git a/Lib/platform.py b/Lib/platform.py
@@ -127,7 +127,7 @@
 # Based on the description of the PHP's version_compare():
 # http://php.net/manual/en/function.version-compare.php
 
-_ver_stages = {
+_ver_stages = frozendict({
     # any string not found in this dict, will get 0 assigned
     'dev': 10,
     'alpha': 20, 'a': 20,
@@ -136,7 +136,7 @@
     'RC': 50, 'rc': 50,
     # number, will get 100 assigned
     'pl': 200, 'p': 200,
-}
+})
 
 
 def _comparable_version(version):
@@ -705,11 +705,11 @@ def _syscmd_file(target, default=''):
 
 # Default values for architecture; non-empty strings override the
 # defaults given as parameters
-_default_architecture = {
+_default_architecture = frozendict({
     'win32': ('', 'WindowsPE'),
     'win16': ('', 'Windows'),
     'dos': ('', 'MSDOS'),
-}
+})
 
 def architecture(executable=sys.executable, bits='', linkage=''):
 

diff --git a/Lib/plistlib.py b/Lib/plistlib.py
@@ -453,7 +453,7 @@ class InvalidFileException (ValueError):
     def __init__(self, message="Invalid file"):
         ValueError.__init__(self, message)
 
-_BINARY_FORMAT = {1: 'B', 2: 'H', 4: 'L', 8: 'Q'}
+_BINARY_FORMAT = frozendict({1: 'B', 2: 'H', 4: 'L', 8: 'Q'})
 
 _undefined = object()
 

@@ -150,7 +150,8 @@
     source=_ssl)
 
 PROTOCOL_SSLv23 = _SSLMethod.PROTOCOL_SSLv23 = _SSLMethod.PROTOCOL_TLS
-_PROTOCOL_NAMES = {value: name for name, value in _SSLMethod.__members__.items()}
+_PROTOCOL_NAMES = frozendict({
+    value: name for name, value in _SSLMethod.__members__.items()})
 
 _SSLv2_IF_EXISTS = getattr(_SSLMethod, 'PROTOCOL_SSLv2', None)
 

diff --git a/Lib/stringprep.py b/Lib/stringprep.py
@@ -21,7 +21,7 @@ def in_table_b1(code):
     return ord(code) in b1_set
 
 
-b3_exceptions = {
+b3_exceptions = frozendict({
 0xb5:'\u03bc', 0xdf:'ss', 0x130:'i\u0307', 0x149:'\u02bcn',
 0x17f:'s', 0x1f0:'j\u030c', 0x345:'\u03b9', 0x37a:' \u03b9',
 0x390:'\u03b9\u0308\u0301', 0x3b0:'\u03c5\u0308\u0301', 0x3c2:'\u03c3', 0x3d0:'\u03b2',
@@ -184,7 +184,7 @@ def in_table_b1(code):
 0x1d79c:'\u03bd', 0x1d79d:'\u03be', 0x1d79e:'\u03bf', 0x1d79f:'\u03c0',
 0x1d7a0:'\u03c1', 0x1d7a1:'\u03b8', 0x1d7a2:'\u03c3', 0x1d7a3:'\u03c4',
 0x1d7a4:'\u03c5', 0x1d7a5:'\u03c6', 0x1d7a6:'\u03c7', 0x1d7a7:'\u03c8',
-0x1d7a8:'\u03c9', 0x1d7bb:'\u03c3', }
+0x1d7a8:'\u03c9', 0x1d7bb:'\u03c3', })
 
 def map_table_b3(code):
     r = b3_exceptions.get(ord(code))

diff --git a/Lib/symtable.py b/Lib/symtable.py
@@ -414,7 +414,7 @@ def get_namespace(self):
 _flags = [('USE', USE)]
 _flags.extend(kv for kv in globals().items() if kv[0].startswith('DEF_'))
 _scopes_names = ('FREE', 'LOCAL', 'GLOBAL_IMPLICIT', 'GLOBAL_EXPLICIT', 'CELL')
-_scopes_value_to_name = {globals()[n]: n for n in _scopes_names}
+_scopes_value_to_name = frozendict({globals()[n]: n for n in _scopes_names})
 
 
 def main(args):

@@ -860,11 +860,11 @@ def data_filter(member, dest_path):
         return member.replace(**new_attrs, deep=False)
     return member
 
-_NAMED_FILTERS = {
+_NAMED_FILTERS = frozendict({
     "fully_trusted": fully_trusted_filter,
     "tar": tar_filter,
     "data": data_filter,
-}
+})
 
 #------------------
 # Exported Classes

diff --git a/Lib/typing.py b/Lib/typing.py
@@ -1916,7 +1916,7 @@ def _allow_reckless_class_checks(depth=2):
     return _caller(depth) in {'abc', '_py_abc', 'functools', None}
 
 
-_PROTO_ALLOWLIST = {
+_PROTO_ALLOWLIST = frozendict({
     'collections.abc': [
         'Callable', 'Awaitable', 'Iterable', 'Iterator', 'AsyncIterable',
         'AsyncIterator', 'Hashable', 'Sized', 'Container', 'Collection',
@@ -1925,7 +1925,7 @@ def _allow_reckless_class_checks(depth=2):
     'contextlib': ['AbstractContextManager', 'AbstractAsyncContextManager'],
     'io': ['Reader', 'Writer'],
     'os': ['PathLike'],
-}
+})
 
 
 @functools.cache