Fix custom dict overriding in collections

src/monty/collections.py

@@ -1,17 +1,27 @@
 """
-Useful collection classes, e.g., tree, frozendict, etc.
+Useful collection classes:
+    - tree: A recursive `defaultdict` for creating nested dictionaries
+        with default values.
+    - ControlledDict: A base dict class with configurable mutability.
+    - frozendict: An immutable dictionary.
+    - Namespace: A dict doesn't allow changing values, but could
+        add new keys,
+    - AttrDict: A dict whose values could be access as `dct.key`.
+    - FrozenAttrDict: An immutable version of `AttrDict`.
+    - MongoDict: A dict-like object whose values are nested dicts
+        could be accessed as attributes.
 """
 
 from __future__ import annotations
 
 import collections
+import warnings
+from abc import ABC
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
     from typing import Any, Iterable
 
-    from typing_extensions import Self
-
 
 def tree() -> collections.defaultdict:
     """
@@ -20,126 +30,202 @@ def tree() -> collections.defaultdict:
 
     Usage:
         x = tree()
-        x['a']['b']['c'] = 1
+        x["a"]["b"]["c"] = 1
 
     Returns:
         A tree.
     """
     return collections.defaultdict(tree)
 
 
-class frozendict(dict):
+class ControlledDict(collections.UserDict, ABC):
     """
-    A dictionary that does not permit changes. The naming
-    violates PEP8 to be consistent with standard Python's "frozenset" naming.
+    A base dictionary class with configurable mutability.
+
+    Attributes:
+        _allow_add (bool): Whether new keys can be added.
+        _allow_del (bool): Whether existing keys can be deleted.
+        _allow_update (bool): Whether existing keys can be updated.
+
+    Configurable Operations:
+        This class allows controlling the following dict operations (refer to
+        https://docs.python.org/3.13/library/stdtypes.html#mapping-types-dict for details):
+
+        - Adding or updating items:
+            - setter method: `__setitem__`
+            - `setdefault`
+            - `update`
+
+        - Deleting items:
+            - `del dict[key]`
+            - `pop(key)`
+            - `popitem`
+            - `clear()`
     """
 
-    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)
+    _allow_add: bool = True
+    _allow_del: bool = True
+    _allow_update: bool = True
 
-    def __setitem__(self, key: Any, val: Any) -> None:
-        raise KeyError(f"Cannot overwrite existing key: {str(key)}")
+    def __init__(self, *args, **kwargs) -> None:
+        """Temporarily allow add during initialization."""
+        original_allow_add = self._allow_add
 
-    def update(self, *args, **kwargs) -> None:
-        """
-        Args:
-            args: Passthrough arguments for standard dict.
-            kwargs: Passthrough keyword arguments for standard dict.
-        """
-        raise KeyError(f"Cannot update a {self.__class__.__name__}")
+        try:
+            self._allow_add = True
+            super().__init__(*args, **kwargs)
+        finally:
+            self._allow_add = original_allow_add
 
+    # Override add/update operations
+    def __setitem__(self, key, value) -> None:
+        """Forbid adding or updating keys based on _allow_add and _allow_update."""
+        if key not in self.data and not self._allow_add:
+            raise TypeError(f"Cannot add new key {key!r}, because add is disabled.")
+        elif key in self.data and not self._allow_update:
+            raise TypeError(f"Cannot update key {key!r}, because update is disabled.")
 
-class Namespace(dict):
-    """A dictionary that does not permit to redefine its keys."""
+        super().__setitem__(key, value)
 
-    def __init__(self, *args, **kwargs) -> None:
-        """
-        Args:
-            args: Passthrough arguments for standard dict.
-            kwargs: Passthrough keyword arguments for standard dict.
+    def update(self, *args, **kwargs) -> None:
+        """Forbid adding or updating keys based on _allow_add and _allow_update."""
+        for key in dict(*args, **kwargs):
+            if key not in self.data and not self._allow_add:
+                raise TypeError(
+                    f"Cannot add new key {key!r} using update, because add is disabled."
+                )
+            elif key in self.data and not self._allow_update:
+                raise TypeError(
+                    f"Cannot update key {key!r} using update, because update is disabled."
+                )
+
+        super().update(*args, **kwargs)
+
+    def setdefault(self, key, default=None) -> Any:
+        """Forbid adding or updating keys based on _allow_add and _allow_update.
+
+        Note: if not _allow_update, this method would NOT check whether the
+            new default value is the same as current value for efficiency.
         """
-        self.update(*args, **kwargs)
+        if key not in self.data:
+            if not self._allow_add:
+                raise TypeError(
+                    f"Cannot add new key using setdefault: {key!r}, because add is disabled."
+                )
+        elif not self._allow_update:
+            raise TypeError(
+                f"Cannot update key using setdefault: {key!r}, because update is disabled."
+            )
+
+        return super().setdefault(key, default)
+
+    # Override delete operations
+    def __delitem__(self, key) -> None:
+        """Forbid deleting keys when self._allow_del is False."""
+        if not self._allow_del:
+            raise TypeError(f"Cannot delete key {key!r}, because delete is disabled.")
+        super().__delitem__(key)
+
+    def pop(self, key, *args):
+        """Forbid popping keys when self._allow_del is False."""
+        if not self._allow_del:
+            raise TypeError(f"Cannot pop key {key!r}, because delete is disabled.")
+        return super().pop(key, *args)
+
+    def popitem(self):
+        """Forbid popping the last item when self._allow_del is False."""
+        if not self._allow_del:
+            raise TypeError("Cannot pop item, because delete is disabled.")
+        return super().popitem()
+
+    def clear(self) -> None:
+        """Forbid clearing the dictionary when self._allow_del is False."""
+        if not self._allow_del:
+            raise TypeError("Cannot clear dictionary, because delete is disabled.")
+        super().clear()
+
+
+class frozendict(ControlledDict):
+    """
+    A dictionary that does not permit changes. The naming
+    violates PEP 8 to be consistent with the built-in `frozenset` naming.
+    """
 
-    def __setitem__(self, key: Any, val: Any) -> None:
-        if key in self:
-            raise KeyError(f"Cannot overwrite existent key: {key!s}")
+    _allow_add: bool = False
+    _allow_del: bool = False
+    _allow_update: bool = False
 
-        dict.__setitem__(self, key, val)
 
-    def update(self, *args, **kwargs) -> None:
-        """
-        Args:
-            args: Passthrough arguments for standard dict.
-            kwargs: Passthrough keyword arguments for standard dict.
-        """
-        for k, v in dict(*args, **kwargs).items():
-            self[k] = v
+class Namespace(ControlledDict):
+    """A dictionary that does not permit update/delete its values (but allows add)."""
+
+    _allow_add: bool = True
+    _allow_del: bool = False
+    _allow_update: bool = False
 
 
 class AttrDict(dict):
     """
-    Allows to access dict keys as obj.foo in addition
-    to the traditional way obj['foo']"
+    Allow accessing values as `dct.key` in addition to the traditional way `dct["key"]`.
 
     Examples:
-        >>> d = AttrDict(foo=1, bar=2)
-        >>> assert d["foo"] == d.foo
-        >>> d.bar = "hello"
-        >>> assert d.bar == "hello"
+        >>> dct = AttrDict(foo=1, bar=2)
+        >>> assert dct["foo"] is dct.foo
+        >>> dct.bar = "hello"
+
+    Warnings:
+        When shadowing dict methods, e.g.:
+            >>> dct = AttrDict(update="value")
+            >>> dct.update()  # TypeError (the `update` method is overwritten)
+
+    References:
+        https://stackoverflow.com/a/14620633/24021108
     """
 
     def __init__(self, *args, **kwargs) -> None:
-        """
-        Args:
-            args: Passthrough arguments for standard dict.
-            kwargs: Passthrough keyword arguments for standard dict.
-        """
-        super().__init__(*args, **kwargs)
+        super(AttrDict, self).__init__(*args, **kwargs)
         self.__dict__ = self
 
-    def copy(self) -> Self:
-        """
-        Returns:
-            Copy of AttrDict
-        """
-        newd = super().copy()
-        return self.__class__(**newd)
+    def __setitem__(self, key, value) -> None:
+        """Check if the key shadows dict method."""
+        if key in dir(dict):
+            warnings.warn(
+                f"'{key=}' shadows dict method. This may lead to unexpected behavior.",
+                UserWarning,
+                stacklevel=2,
+            )
+        super().__setitem__(key, value)
 
 
 class FrozenAttrDict(frozendict):
     """
     A dictionary that:
-        * does not permit changes.
-        * Allows to access dict keys as obj.foo in addition
-          to the traditional way obj['foo']
+        - Does not permit changes (add/update/delete).
+        - Allows accessing values as `dct.key` in addition to
+            the traditional way `dct["key"]`.
     """
 
     def __init__(self, *args, **kwargs) -> None:
-        """
-        Args:
-            args: Passthrough arguments for standard dict.
-            kwargs: Passthrough keyword arguments for standard dict.
-        """
+        """Allow add during init, as __setattr__ is called unlike frozendict."""
+        self._allow_add = True
         super().__init__(*args, **kwargs)
+        self._allow_add = False
 
     def __getattribute__(self, name: str) -> Any:
         try:
-            return super().__getattribute__(name)
+            return object.__getattribute__(self, name)
         except AttributeError:
-            try:
-                return self[name]
-            except KeyError as exc:
-                raise AttributeError(str(exc))
+            return self[name]
 
     def __setattr__(self, name: str, value: Any) -> None:
-        raise KeyError(
-            f"You cannot modify attribute {name} of {self.__class__.__name__}"
-        )
+        if not self._allow_add and name != "_allow_add":
+            raise TypeError(
+                f"{self.__class__.__name__} does not support item assignment."
+            )
+        super().__setattr__(name, value)
+
+    def __delattr__(self, name: str) -> None:
+        raise TypeError(f"{self.__class__.__name__} does not support item deletion.")
 
 
 class MongoDict:
@@ -151,11 +237,11 @@ class MongoDict:
     a nested dict interactively (e.g. documents extracted from a MongoDB
     database).
 
-    >>> m = MongoDict({'a': {'b': 1}, 'x': 2})
-    >>> assert m.a.b == 1 and m.x == 2
-    >>> assert "a" in m and "b" in m.a
-    >>> m["a"]
-    {'b': 1}
+    >>> m_dct = MongoDict({"a": {"b": 1}, "x": 2})
+    >>> assert m_dct.a.b == 1 and m_dct.x == 2
+    >>> assert "a" in m_dct and "b" in m_dct.a
+    >>> m_dct["a"]
+    {"b": 1}
 
     Notes:
         Cannot inherit from ABC collections.Mapping because otherwise
@@ -186,7 +272,6 @@ def __getattribute__(self, name: str) -> Any:
         try:
             return super().__getattribute__(name)
         except AttributeError:
-            # raise
             try:
                 a = self._mongo_dict_[name]
                 if isinstance(a, collections.abc.Mapping):
@@ -214,26 +299,25 @@ def __dir__(self) -> list:
 
 def dict2namedtuple(*args, **kwargs) -> tuple:
     """
-    Helper function to create a class `namedtuple` from a dictionary.
+    Helper function to create a `namedtuple` from a dictionary.
 
     Examples:
-        >>> t = dict2namedtuple(foo=1, bar="hello")
-        >>> assert t.foo == 1 and t.bar == "hello"
+        >>> tpl = dict2namedtuple(foo=1, bar="hello")
+        >>> assert tpl.foo == 1 and tpl.bar == "hello"
 
-        >>> t = dict2namedtuple([("foo", 1), ("bar", "hello")])
-        >>> assert t[0] == t.foo and t[1] == t.bar
+        >>> tpl = dict2namedtuple([("foo", 1), ("bar", "hello")])
+        >>> assert tpl[0] is tpl.foo and tpl[1] is tpl.bar
 
     Warnings:
         - The order of the items in the namedtuple is not deterministic if
-          kwargs are used.
-          namedtuples, however, should always be accessed by attribute hence
-          this behaviour should not represent a serious problem.
+          `kwargs` are used. namedtuples, however, should always be accessed
+          by attribute hence this behaviour should not be a serious problem.
 
-        - Don't use this function in code in which memory and performance are
-          crucial since a dict is needed to instantiate the tuple!
+        - Don't use this function in code where memory and performance are
+          crucial, since a dict is needed to instantiate the tuple!
     """
-    d = collections.OrderedDict(*args)
-    d.update(**kwargs)
+    dct = collections.OrderedDict(*args)
+    dct.update(**kwargs)
     return collections.namedtuple(
-        typename="dict2namedtuple", field_names=list(d.keys())
-    )(**d)
+        typename="dict2namedtuple", field_names=list(dct.keys())
+    )(**dct)

src/monty/design_patterns.py

@@ -7,9 +7,12 @@
 import inspect
 import os
 from functools import wraps
-from typing import Any, Dict, Hashable, Tuple, TypeVar
+from typing import TYPE_CHECKING, TypeVar
 from weakref import WeakValueDictionary
 
+if TYPE_CHECKING:
+    from typing import Any
+
 
 def singleton(cls):
     """
@@ -95,7 +98,7 @@ def new_init(self: Any, *args: Any, **kwargs: Any) -> None:
             orig_init(self, *args, **kwargs)
             self._initialized = True
 
-    def reduce(self: Any) -> Tuple[type, Tuple, Dict[str, Any]]:
+    def reduce(self: Any) -> tuple[type, tuple, dict[str, Any]]:
         for key, value in cache.items():
             if value is self:
                 cls, args = key