fix controlled dict init

src/monty/collections.py

@@ -68,6 +68,18 @@ class ControlledDict(collections.UserDict, ABC):
     allow_del: ClassVar[bool] = True
     allow_update: ClassVar[bool] = True
 
+    def __init__(self, *args, **kwargs):
+        """Temporarily allow all add/update during initialization."""
+        original_allow_add = self.allow_add
+        original_allow_update = self.allow_update
+        try:
+            self.allow_add = True
+            self.allow_update = True
+            super().__init__(*args, **kwargs)
+        finally:
+            self.allow_add = original_allow_add
+            self.allow_update = original_allow_update
+
     # TODO: extract checkers
 
     # Overriding add/update operations
@@ -142,30 +154,15 @@ def clear(self):
         super().clear()
 
 
-class frozendict(dict):
+class frozendict(ControlledDict):
     """
     A dictionary that does not permit changes. The naming
-    violates PEP 8 to be consistent with the built-in "frozenset" naming.
+    violates PEP 8 to be consistent with the built-in `frozenset` naming.
     """
 
-    def __init__(self, *args, **kwargs) -> None:
-        """
-        Args:
-            args: Passthrough arguments for standard dict.
-            kwargs: Passthrough keyword arguments for standard dict.
-        """
-        dict.__init__(self, *args, **kwargs)
-
-    def __setitem__(self, key: Any, val: Any) -> None:
-        raise TypeError(f"{type(self).__name__} does not support item assignment")
-
-    def update(self, *args, **kwargs) -> None:
-        """
-        Args:
-            args: Passthrough arguments for standard dict.
-            kwargs: Passthrough keyword arguments for standard dict.
-        """
-        raise TypeError(f"Cannot update a {self.__class__.__name__}")
+    allow_add: ClassVar[bool] = False
+    allow_del: ClassVar[bool] = False
+    allow_update: ClassVar[bool] = False
 
 
 class Namespace(dict):  # TODO: this name is a bit confusing, deprecate it?

tests/test_collections.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from collections import UserDict
+
 import pytest
 
 from monty.collections import (
@@ -108,32 +110,42 @@ def test_del_disabled(self):
         with pytest.raises(TypeError, match="delete is disabled"):
             dct.clear()
 
+    def test_frozen_like(self):
+        """Make sure setter is allow at init time."""
+        ControlledDict.allow_add = False
+        ControlledDict.allow_update = False
+
+        dct = ControlledDict({"hello": "world"})
+        assert isinstance(dct, UserDict)
+        assert dct["hello"] == "world"
+
+        assert not dct.allow_add
+        assert not dct.allow_update
+
 
 def test_frozendict():
     dct = frozendict({"hello": "world"})
-    assert isinstance(dct, dict)
+    assert isinstance(dct, UserDict)
     assert dct["hello"] == "world"
 
+    assert not dct.allow_add
+    assert not dct.allow_update
+    assert not dct.allow_del
+
     # Test setter
-    with pytest.raises(TypeError, match="Cannot overwrite existing key"):
-        dct["key"] == "val"
+    with pytest.raises(TypeError, match="allow_add is set to False"):
+        dct["key"] = "val"
 
     # Test update
-    with pytest.raises(TypeError, match="Cannot overwrite existing key"):
+    with pytest.raises(TypeError, match="allow_add is set to False"):
         dct.update(key="val")
 
-    # Test inplace-or (|=)
-    with pytest.raises(TypeError, match="Cannot overwrite existing key"):
-        dct |= {"key": "val"}
-
-    # TODO: from this point we need a different error message
-
     # Test pop
-    with pytest.raises(TypeError, match="Cannot overwrite existing key"):
+    with pytest.raises(TypeError, match="delete is disabled"):
         dct.pop("key")
 
     # Test delete
-    with pytest.raises(TypeError, match="Cannot overwrite existing key"):
+    with pytest.raises(TypeError, match="delete is disabled"):
         del dct["key"]