restructured mixins

README.md

@@ -1,49 +1,76 @@
 # Hooked Containers
 
-Hooked Containers provides an abstract container foundation that calls a function hook whenever its contents are changed through its API. The aim is to retain familiar Python container operations while letting application code react to additions, replacements, and removals.
+Hooked Containers adds optional, shallow mutation callbacks to familiar Python container operations. It provides `HookedMapping[K, V]`, `HookedList[T]`, and `HookedSet[T]`, backed by owned `dict`, `list`, and `set` storage. Requires Python 3.12 or newer.
 
 ## Mixin Design
 
-The design follows Python's [collections.abc abstract base classes](https://docs.python.org/3/library/collections.abc.html#collections-abstract-base-classes). Separate mixin classes should build up functionality in layers, so a custom container can compose the behavior it needs:
+All reusable container behavior lives in `src/hooked_containers/mixins.py`. The design uses Python's [collections.abc abstract base classes](https://docs.python.org/3/library/collections.abc.html#collections-abstract-base-classes) directly. Three mutable mixins compose shared reads and hook dispatch with their required primitives; standard ABC methods supply the helpers:
 
-| Layer            | Responsibility                                                                              |
-| ---------------- | ------------------------------------------------------------------------------------------- |
-| Container        | Membership testing through `__contains__`.                                                   |
-| Collection       | Iteration and size through `__iter__` and `__len__`, alongside membership.                     |
-| Hook support     | A shared callback and change-event reporting for mutation methods.                           |
-| Sequence         | Indexed access through `__getitem__`, with sequence helpers such as `index` and `count`.      |
-| Mutable sequence | Assignment, deletion, and insertion, supporting helpers such as `append`, `extend`, and `pop`. |
-| Mapping          | Key-based access, iteration over keys, and helpers such as `keys`, `items`, and `values`.     |
-| Mutable mapping  | Assignment and deletion, supporting helpers such as `update`, `setdefault`, and `pop`.        |
+| Mixin | Backing Storage | Responsibility |
+| --- | --- | --- |
+| `ContainerMixin` | Any collection | Containment, iteration, length, and representation. |
+| `HookMixin` | None | Callback dispatch after successful writes. |
+| `ListMixin` | `list` | Indexed reads and writes, insertion, and native list operations. |
+| `MutableMappingMixin` | `dict` | Key-based reads and writes, copying, and merging. |
+| `MutableSetMixin` | `set` | Addition, discard, and named set operations. |
 
-Sequences and mappings are separate branches built on the common container foundation, not successive steps in a single inheritance chain. Mutation hooks belong in the primitive operations so inherited ABC mixin methods also report changes. A compound operation may therefore invoke the hook more than once.
+`HookMixin` shares callback dispatch across the three mixins. Inherited methods such as `append`, `extend`, `reverse`, `update`, `clear`, and set in-place operators reach the primitive writes automatically. A compound operation may invoke the hook more than once.
 
-This layered separation is the intended architecture. Currently, `HookedContainer` combines shared container and hook behavior; `HookedList` and `HookedMapping` extend it with the standard library's `MutableSequence` and `MutableMapping` mixins, respectively.
+Each subclass initializes a single `_storage` attribute with the corresponding native container. There is no storage property or separate container-specific read-only hierarchy. Each of `sequence.py`, `mapping.py`, and `set.py` defines just one concrete wrapper, composing its mutable mixin and adding construction. Representation comes from `ContainerMixin`. Dict-style `popitem` intentionally removes the most recently inserted key, unlike the ABC's arbitrary-item implementation.
+
+Custom containers can use the mixins without any concrete wrapper:
+
+```python
+from hooked_containers.mixins import MutableMappingMixin
+
+
+class Settings(MutableMappingMixin[str, int]):
+    def __init__(self, hook=None):
+        self._storage = {}
+        self.hook = hook
+```
 
 ## Change Hooks
 
-A hook receives one change-event object after a mutation. The event identifies the root container (`root`), the index or key path (`path`), and the affected value (`item`). The current event types are `AddItemEvent`, `SetItemEvent`, and `RemoveItemEvent`.
+A hook receives one immutable `Change(operation, key, value)` record after a write:
+
+| Field | Meaning |
+| --- | --- |
+| `operation` | `"add"`, `"set"`, or `"remove"` |
+| `key` | Mapping key, normalized list index, list slice, or `None` for sets |
+| `value` | Added/new value, or the value that was removed |
 
 ```python
-from hooked_containers.mapping import HookedMapping
-from hooked_containers.sequence import HookedList
+from hooked_containers import HookedList, HookedMapping, HookedSet
 
 
-def on_change(event):
-	print(type(event).__name__, event.path, event.item)
+def on_change(change):
+    print(change.operation, change.key, change.value)
 
 
 items = HookedList(["first"], hook=on_change)
-items.append("second")       # AddItemEvent (1,) second
-items[0] = "updated"         # SetItemEvent (0,) updated
-del items[1]                 # RemoveItemEvent (1,) second
+items.append("second")       # add 1 second
+items[0] = "updated"         # set 0 updated
+del items[1]                 # remove 1 second
 
 settings = HookedMapping({}, hook=on_change)
-settings["enabled"] = True  # AddItemEvent ('enabled',) True
+settings["enabled"] = True   # add enabled True
+
+members = HookedSet(hook=on_change)
+members.add("ready")         # add None ready
+members.discard("ready")     # remove None ready
 ```
 
-The wrappers can share existing mutable storage. Mutating that storage directly bypasses the hook; make changes through the hooked container to receive events. Hooks are optional, and nested wrappers retain the root and path for supported nested container types.
+Reads never change data or invoke the callback. Missing mapping keys raise `KeyError`, and `get` respects its default. Integer list keys are normalized against the length before the write; insertions report their clamped destination. Slice keys preserve the supplied slice in pre-write coordinates, and their values are shallow lists of new or removed items. Sorting and in-place repetition report a whole-list `"set"` using `slice(None)`.
 
-## Status
+Assignments notify even when assigning an equal value. Duplicate set additions, missing set discards, empty clears, and empty slice writes do not notify. Failed primitive writes do not notify; writes completed before a compound operation fails remain reported. A failed sort reports any resulting rearrangement. Callback exceptions propagate after the write without rolling it back. Callbacks that mutate the same container can trigger further callbacks; there is no batching or reentrancy guard.
 
-Requires Python 3.12 or newer. This repository is an early implementation of the container and mixin design; the API and separation of responsibilities may evolve.
+Construction copies the outer storage without notifying. Nested values are not copied or wrapped, and mutations inside those values are not observed. Copies, slices, and non-mutating derived results are ordinary native containers without hooks. Event values are shallow references, not deep snapshots; later changes to a mutable value remain visible through that reference. Direct changes to private storage bypass callbacks.
+
+Set comparison, algebra, and in-place methods follow the standard ABC implementations. In particular, ABC set operators accept iterables more broadly than built-in `set` operators. These wrappers implement container interfaces, not built-in subclass identity or exact built-in performance guarantees.
+
+## Migration
+
+Custom subclasses now initialize `_storage` directly instead of implementing `_data`. The earlier container/collection hierarchy, read-only sequence, mapping, and set mixins, along with `MutableSequenceMixin`, have been replaced by the shared `ContainerMixin` and the three mutable mixins above. Import reusable mixins from `hooked_containers.mixins` and use native backing storage.
+
+The shallow API replaces the earlier root/path event subclasses and recursive wrapping. Use `change.operation`, `change.key`, and `change.value` instead of event types, `path`, and `item`. `HookedMapping` has independent key and value type parameters. Shared outer storage, autovivification, `suppress_hook`, `get_nested`, and the domain-state classes are no longer supported. The development notebooks are historical experiments with the previous API; the examples above describe the current API.

pyproject.toml

@@ -16,6 +16,8 @@ build-backend = "uv_build"
 [dependency-groups]
 dev = [
     "ipykernel>=7.2.0",
+    "ipywidgets>=8.1.9",
+    "notebook>=7.6.3",
     "rich>=14.3.3",
     "ruff>=0.15.2",
     "ty>=0.0.85",

src/hooked_containers/__init__.py

@@ -0,0 +1,7 @@
+from .events import Change as Change
+from .events import HookFunction as HookFunction
+from .mapping import HookedMapping as HookedMapping
+from .sequence import HookedList as HookedList
+from .set import HookedSet as HookedSet
+
+__all__ = ["Change", "HookFunction", "HookedMapping", "HookedList", "HookedSet"]

src/hooked_containers/container.py

@@ -1,35 +0,0 @@
-from abc import ABC
-from abc import abstractmethod
-from collections.abc import MutableMapping
-from collections.abc import MutableSequence
-
-from . import events as e
-from .mixins import CollectionMixin
-from .mixins import HookMixin
-from .types import MutableNesting
-
-
-class HookedContainer[T](HookMixin, CollectionMixin[T], ABC):
-    _data: MutableMapping[T, MutableNesting[T]] | MutableSequence[T]
-
-    def __repr__(self):
-        return f"{self.__class__.__name__}({self._data!r})"
-
-    @abstractmethod
-    def __getitem__(self, key): ...
-
-    def __setitem__(self, s, value):
-        self._data[s] = value
-        self._notify(e.SetItemEvent, s, value)
-
-    def __delitem__(self, s):
-        item = self._data[s]
-        del self._data[s]
-        self._notify(e.RemoveItemEvent, s, item)
-
-    def get_nested(self, keys):
-        """Recursively call __getitem__ with each key in the iterable."""
-        result = self
-        for key in keys:
-            result = result[key]
-        return result

src/hooked_containers/events.py

@@ -1,33 +1,19 @@
 from __future__ import annotations
 
-from collections.abc import Collection
+from collections.abc import Callable
 from collections.abc import Hashable
-from collections.abc import Sequence
 from dataclasses import dataclass
-from dataclasses import field
-from typing import Protocol
+from typing import Any
+from typing import Literal
 
 
 @dataclass(frozen=True)
-class ChangeEvent[T]:
-    """Describe a mutation at an index or key path within a root collection."""
+class Change[T]:
+    """Describe a shallow write; removals carry the removed value."""
 
-    root: Collection[object] = field(repr=False)
-    path: Sequence[Hashable | slice]
-    item: T
+    operation: Literal["add", "set", "remove"]
+    key: Hashable | slice | None
+    value: T
 
 
-@dataclass(frozen=True)
-class AddItemEvent[T](ChangeEvent[T]): ...
-
-
-@dataclass(frozen=True)
-class SetItemEvent[T](ChangeEvent[T]): ...
-
-
-@dataclass(frozen=True)
-class RemoveItemEvent[T](ChangeEvent[T]): ...
-
-
-class HookFunction(Protocol):
-    def __call__[T](self, event: ChangeEvent[T]) -> None: ...
+type HookFunction = Callable[[Change[Any]], None]

src/hooked_containers/mapping.py

@@ -1,65 +1,19 @@
-from collections.abc import MutableMapping
-from collections.abc import MutableSequence
+from collections.abc import Iterable
+from collections.abc import Mapping
+from typing import Any
 
-from . import events as e
-from .container import HookedContainer
-from .container import MutableNesting
 from .events import HookFunction
 from .mixins import MutableMappingMixin
 
 
-class HookedMapping[T](MutableMappingMixin[T, MutableNesting[T]], HookedContainer[T]):
-    _data: MutableMapping[T, MutableNesting[T]]
+class HookedMapping[K, V](MutableMappingMixin[K, V]):
+    """A shallow mapping with optional mutation notifications."""
 
     def __init__(
         self,
-        existing: MutableMapping[T, MutableNesting[T]],
+        existing: Mapping[K, V] | Iterable[tuple[K, V]] = (),
         hook: HookFunction | None = None,
-        root: MutableMapping[T] | None = None,
-        path: MutableSequence[int] | None = None,
-    ):
-        match existing:
-            case HookedMapping(_data=seq):
-                self._data = seq
-            case MutableMapping() as seq:
-                self._data = seq
-            case _:
-                raise TypeError(f"Expected a mapping, got {type(existing)}")
-                # self._data = dict(it)
+        **kwargs: Any,
+    ) -> None:
+        self._storage = dict(existing, **kwargs)
         self.hook = hook
-        self._root = root if root is not None else self
-        self._path = list(path) if path is not None else []
-
-    def __wrap_sub__(self, other, **kwargs):
-        return HookedMapping(other, hook=self.hook, root=self._root, **kwargs)
-
-    def __getitem__(self, key: T) -> MutableNesting[T]:
-        if key not in self._data:
-            return self.__wrap_sub__(self.__setitem__(key, {}), path=self.new_path(key))
-        value = self._data[key]
-        match value:
-            case MutableMapping() as mapping:
-                return self.__wrap_sub__(mapping, path=self.new_path(key))
-            case _ as item:
-                return item
-
-    def __setitem__(
-        self,
-        key: T,
-        value: MutableNesting[T],
-        *,
-        suppress_hook: bool = False,
-    ) -> MutableNesting[T] | None:
-        match value:
-            case HookedMapping(_data=data):
-                event_type = e.SetItemEvent if key in self._data else e.AddItemEvent
-                self._data[key] = data
-                if not suppress_hook:
-                    self._notify(event_type, key, value)
-                return data
-            case _:
-                if suppress_hook:
-                    self._data[key] = value
-                else:
-                    super().__setitem__(key, value)
-        return value

src/hooked_containers/mixins.py

@@ -1,89 +1,65 @@
 from collections.abc import Collection
-from collections.abc import Container
 from collections.abc import Iterable
 from collections.abc import Iterator
-from collections.abc import Mapping
 from collections.abc import MutableMapping
 from collections.abc import MutableSequence
-from collections.abc import Sequence
+from collections.abc import MutableSet
+from operator import index as to_index
 from typing import Any
+from typing import Literal
+from typing import Self
+from typing import SupportsIndex
+from typing import cast
 from typing import overload
 
-from .events import AddItemEvent
-from .events import ChangeEvent
+from .events import Change
 from .events import HookFunction
-from .events import RemoveItemEvent
-from .events import SetItemEvent
-
-
-class ContainerMixin[T](Container[T]):
-    """Provide membership testing against subclass-owned storage."""
-
-    _data: Container[T]
-
-    def __contains__(self, item: object) -> bool:
-        return item in self._data
-
-
-class CollectionMixin[T](ContainerMixin[T], Collection[T]):
-    """Add iteration and size to the container interface."""
-
-    _data: Collection[T]
-
-    def __iter__(self) -> Iterator[T]:
-        return iter(self._data)
-
-    def __len__(self) -> int:
-        return len(self._data)
 
 
 class HookMixin:
-    """Share optional mutation callbacks and root-relative event paths."""
+    """Dispatch shallow changes after successful writes."""
 
     hook: HookFunction | None = None
-    _root: Any = None
-    _path: Sequence[Any] = ()
 
-    def new_path(self, key: Any) -> list[Any]:
-        return [*self._path, key]
-
-    def _notify(self, event_type: type[ChangeEvent[Any]], key: Any, item: Any) -> None:
+    def _notify(self, operation: Literal["add", "set", "remove"], key: Any, value: Any) -> None:
         if self.hook is not None:
-            root = self._root if self._root is not None else self
-            self.hook(event_type(root, self.new_path(key), item))
+            self.hook(Change(operation, key, value))
 
 
-class SequenceMixin[T](CollectionMixin[T], Sequence[T]):
-    """Add indexed access and the standard read-only sequence helpers."""
+class ContainerMixin[T](Collection[T]):
+    """Provide common reads and representation for subclass-owned storage."""
 
-    _data: Sequence[T]
+    _storage: Collection[T]
+
+    def __contains__(self, item: object) -> bool:
+        return item in self._storage
+
+    def __iter__(self) -> Iterator[T]:
+        return iter(self._storage)
+
+    def __len__(self) -> int:
+        return len(self._storage)
+
+    def __repr__(self) -> str:
+        return f"{type(self).__name__}({self._storage!r})"
+
+
+class ListMixin[T](HookMixin, ContainerMixin[T], MutableSequence[T]):
+    """Provide list operations and report writes to subclass-owned storage."""
+
+    _storage: list[T]
 
     @overload
-    def __getitem__(self, index: int) -> T: ...
+    def __getitem__(self, index: SupportsIndex) -> T: ...
 
     @overload
-    def __getitem__(self, index: slice) -> Sequence[T]: ...
+    def __getitem__(self, index: slice) -> list[T]: ...
 
-    def __getitem__(self, index: int | slice) -> T | Sequence[T]:
-        return self._data[index]
-
-
-class MutableSequenceMixin[T](HookMixin, SequenceMixin[T], MutableSequence[T]):
-    """Report primitive mutations used by the mutable sequence helpers."""
-
-    _data: MutableSequence[T]
+    def __getitem__(self, index: SupportsIndex | slice) -> T | list[T]:
+        return self._storage[index if isinstance(index, slice) else to_index(index)]
 
     @overload
-    def __getitem__(self, index: int) -> T: ...
-
-    @overload
-    def __getitem__(self, index: slice) -> MutableSequence[T]: ...
-
-    def __getitem__(self, index: int | slice) -> T | MutableSequence[T]:
-        return self._data[index]
-
-    @overload
-    def __setitem__(self, index: int, value: T) -> None: ...
+    def __setitem__(self, index: SupportsIndex, value: T) -> None: ...
 
     @overload
     def __setitem__(self, index: slice, value: Iterable[T]) -> None: ...
@@ -91,39 +67,188 @@ class MutableSequenceMixin[T](HookMixin, SequenceMixin[T], MutableSequence[T]):
     def __setitem__(self, index: Any, value: Any) -> None:
         if isinstance(index, slice):
             value = list(value)
-        self._data[index] = value
-        self._notify(SetItemEvent, index, value)
+            previous = self._storage[index]
+            self._storage[index] = value
+            if previous or value:
+                self._notify("set", index, value)
+            return
+        index = to_index(index)
+        actual_index = index if index >= 0 else len(self) + index
+        self._storage[index] = value
+        self._notify("set", actual_index, value)
 
-    def __delitem__(self, index: int | slice) -> None:
-        item = self._data[index]
-        del self._data[index]
-        self._notify(RemoveItemEvent, index, item)
+    def __delitem__(self, index: SupportsIndex | slice) -> None:
+        if not isinstance(index, slice):
+            index = to_index(index)
+        item = self._storage[index]
+        actual_index = index if isinstance(index, slice) or index >= 0 else len(self) + index
+        del self._storage[index]
+        if not isinstance(index, slice) or item:
+            self._notify("remove", actual_index, item)
 
-    def insert(self, index: int, value: T) -> None:
-        self._data.insert(index, value)
-        self._notify(AddItemEvent, index, value)
+    def insert(self, index: SupportsIndex, value: T) -> None:
+        index = to_index(index)
+        index = min(index, len(self)) if index >= 0 else max(0, len(self) + index)
+        self._storage.insert(index, value)
+        self._notify("add", index, value)
+
+    @staticmethod
+    def _operand(other: Any) -> Any:
+        return other._storage if isinstance(other, ListMixin) else other
+
+    def __eq__(self, other: object) -> bool:
+        return self._storage.__eq__(self._operand(other))
+
+    def __lt__(self, other: Any) -> bool:
+        return self._storage.__lt__(self._operand(other))
+
+    def __le__(self, other: Any) -> bool:
+        return self._storage.__le__(self._operand(other))
+
+    def __gt__(self, other: Any) -> bool:
+        return self._storage.__gt__(self._operand(other))
+
+    def __ge__(self, other: Any) -> bool:
+        return self._storage.__ge__(self._operand(other))
+
+    def copy(self) -> list[T]:
+        return self._storage.copy()
+
+    def __add__(self, other: Any) -> list[T]:
+        return self._storage.__add__(self._operand(other))
+
+    def __radd__(self, other: Any) -> list[T]:
+        if not isinstance(other, list):
+            return NotImplemented
+        return other + self._storage
+
+    def __mul__(self, count: SupportsIndex) -> list[T]:
+        return self._storage * count
+
+    def __rmul__(self, count: SupportsIndex) -> list[T]:
+        return self * count
+
+    def __imul__(self, count: SupportsIndex) -> Self:
+        count = to_index(count)
+        if self and count != 1:
+            self[:] = self._storage * count
+        return self
+
+    def sort(self, *, key: Any = None, reverse: bool = False) -> None:
+        values = self._storage
+        before = tuple(map(id, values))
+        try:
+            values.sort(key=key, reverse=reverse)
+        except Exception:
+            if tuple(map(id, values)) != before:
+                self._notify("set", slice(None), list(values))
+            raise
+        if values:
+            self._notify("set", slice(None), list(values))
 
 
-class MappingMixin[K, V](CollectionMixin[K], Mapping[K, V]):
-    """Add key-based access and the standard read-only mapping helpers."""
+class MutableMappingMixin[K, V](HookMixin, ContainerMixin[K], MutableMapping[K, V]):
+    """Provide mapping operations and report writes to subclass-owned storage."""
 
-    _data: Mapping[K, V]
+    _storage: dict[K, V]
 
     def __getitem__(self, key: K) -> V:
-        return self._data[key]
+        return self._storage[key]
 
+    def __reversed__(self) -> Iterator[K]:
+        return reversed(self._storage)
 
-class MutableMappingMixin[K, V](HookMixin, MappingMixin[K, V], MutableMapping[K, V]):
-    """Report primitive mutations used by the mutable mapping helpers."""
+    def copy(self) -> dict[K, V]:
+        return self._storage.copy()
 
-    _data: MutableMapping[K, V]
+    def __or__(self, other: Any) -> dict[K, V]:
+        if not isinstance(other, (dict, MutableMappingMixin)):
+            return NotImplemented
+        return self._storage | dict(other)
+
+    def __ror__(self, other: Any) -> dict[K, V]:
+        if not isinstance(other, (dict, MutableMappingMixin)):
+            return NotImplemented
+        return dict(other) | self._storage
 
     def __setitem__(self, key: K, value: V) -> None:
-        event_type = SetItemEvent if key in self._data else AddItemEvent
-        self._data[key] = value
-        self._notify(event_type, key, value)
+        operation: Literal["add", "set"] = "set" if key in self._storage else "add"
+        self._storage[key] = value
+        self._notify(operation, key, value)
 
     def __delitem__(self, key: K) -> None:
-        item = self._data[key]
-        del self._data[key]
-        self._notify(RemoveItemEvent, key, item)
+        item = self._storage[key]
+        del self._storage[key]
+        self._notify("remove", key, item)
+
+    def popitem(self) -> tuple[K, V]:
+        if not self:
+            raise KeyError("popitem(): mapping is empty")
+        key = next(reversed(self))
+        value = self[key]
+        del self[key]
+        return key, value
+
+    def __ior__(self, other: Any) -> Self:
+        self.update(other)
+        return self
+
+
+class MutableSetMixin[T](HookMixin, ContainerMixin[T], MutableSet[T]):
+    """Provide set operations and report writes to subclass-owned storage."""
+
+    _storage: set[T]
+
+    @classmethod
+    def _from_iterable[S](cls, iterable: Iterable[S]) -> set[S]:
+        return set(iterable)
+
+    def copy(self) -> set[T]:
+        return self._storage.copy()
+
+    def union(self, *others: Iterable[T]) -> set[T]:
+        return self._storage.union(*others)
+
+    def intersection(self, *others: Iterable[T]) -> set[T]:
+        return self._storage.intersection(*others)
+
+    def difference(self, *others: Iterable[T]) -> set[T]:
+        return self._storage.difference(*others)
+
+    def symmetric_difference(self, other: Iterable[T]) -> set[T]:
+        return self._storage.symmetric_difference(other)
+
+    def issubset(self, other: Iterable[T]) -> bool:
+        return self._storage.issubset(other)
+
+    def issuperset(self, other: Iterable[T]) -> bool:
+        return self._storage.issuperset(other)
+
+    def add(self, value: T) -> None:
+        size = len(self._storage)
+        self._storage.add(value)
+        if len(self._storage) != size:
+            self._notify("add", None, value)
+
+    def discard(self, value: T) -> None:
+        if value in self._storage:
+            removed = value
+            if self.hook is not None:
+                removed = next(item for item in self._storage if item is value or item == value)
+            self._storage.remove(value)
+            self._notify("remove", None, removed)
+
+    def update(self, *others: Iterable[T]) -> None:
+        for other in others:
+            self.__ior__(cast(Any, other))
+
+    def difference_update(self, *others: Iterable[T]) -> None:
+        for other in others:
+            self.__isub__(cast(Any, other))
+
+    def intersection_update(self, *others: Iterable[T]) -> None:
+        remaining = self.intersection(*others)
+        self.__iand__(remaining)
+
+    def symmetric_difference_update(self, other: Iterable[T]) -> None:
+        self.__ixor__(cast(Any, other))

src/hooked_containers/sequence.py

@@ -1,39 +1,12 @@
-from collections.abc import MutableSequence
+from collections.abc import Iterable
 
-from .container import HookedContainer
 from .events import HookFunction
-from .mixins import MutableSequenceMixin
-from .types import MutableNesting
+from .mixins import ListMixin
 
 
-class HookedList[T](MutableSequenceMixin[T], HookedContainer[T]):
-    _data: MutableSequence[T]
-    path: MutableSequence[int]
+class HookedList[T](ListMixin[T]):
+    """A shallow list with optional mutation notifications."""
 
-    def __init__(
-        self,
-        existing: MutableSequence[T],
-        hook: HookFunction | None = None,
-        root: MutableNesting[T] | None = None,
-        path: MutableSequence[int] | None = None,
-    ) -> None:
+    def __init__(self, existing: Iterable[T] = (), hook: HookFunction | None = None) -> None:
+        self._storage = list(existing)
         self.hook = hook
-        match existing:
-            case HookedContainer(_data=seq):
-                self._data = seq
-            case MutableSequence() as seq:
-                self._data = seq
-            case _ as it:
-                self._data = list(it)
-        self._root = root if root is not None else self
-        self._path = list(path) if path is not None else []
-
-    def __getitem__(self, s):
-        new_path = self.new_path(s)
-        match self._data[s]:
-            case HookedContainer(_data=seq):
-                return type(self)(seq, self.hook, root=self._root, path=new_path)
-            case MutableSequence() as seq:
-                return HookedList(seq, self.hook, root=self._root, path=new_path)
-            case _ as item:
-                return item

src/hooked_containers/set.py

@@ -0,0 +1,12 @@
+from collections.abc import Iterable
+
+from .events import HookFunction
+from .mixins import MutableSetMixin
+
+
+class HookedSet[T](MutableSetMixin[T]):
+    """A shallow set with optional mutation notifications."""
+
+    def __init__(self, existing: Iterable[T] = (), hook: HookFunction | None = None) -> None:
+        self._storage = set(existing)
+        self.hook = hook

src/hooked_containers/state.py

@@ -1,43 +0,0 @@
-from collections.abc import MutableMapping
-from datetime import datetime
-
-from .mapping import HookedMapping
-
-
-class EntityState(HookedMapping[str]):
-    def __setitem__(self, key, value):
-        super().__setitem__(key, value)
-        super().__setitem__("last_changed", datetime.now(), suppress_hook=True)
-
-
-class DomainState(HookedMapping[str]):
-    _data: MutableMapping[str, EntityState]
-
-    def __getitem__(self, key):
-        match super().__getitem__(key):
-            case HookedMapping(_data=val):
-                return EntityState(val, hook=self.hook, path=self.new_path(key))
-            case _ as val:
-                raise TypeError(f"Expected a mapping for domain state, got {type(val)}")
-
-
-class NameSpaceState(HookedMapping[str]):
-    _data: MutableMapping[str, DomainState]
-
-    def __getitem__(self, key):
-        match super().__getitem__(key):
-            case HookedMapping(_data=val):
-                return DomainState(val, hook=self.hook, path=self.new_path(key))
-            case _ as val:
-                raise TypeError(f"Expected a mapping for domain state, got {type(val)}")
-
-
-class FullState(HookedMapping[str]):
-    _data: MutableMapping[str, NameSpaceState]
-
-    def __getitem__(self, key):
-        match super().__getitem__(key):
-            case HookedMapping(_data=val):
-                return NameSpaceState(val, hook=self.hook, path=self.new_path(key))
-            case _ as val:
-                raise TypeError(f"Expected a mapping for namespace state, got {type(val)}")

src/hooked_containers/types.py

@@ -1,6 +0,0 @@
-from collections.abc import MutableMapping, MutableSequence
-from typing import TypeVar
-
-T = TypeVar("T")
-
-type MutableNesting[T] = T | MutableSequence[T] | MutableMapping[T, MutableNesting[T]]

tests/test_mapping.py

@@ -1,37 +1,73 @@
-from dataclasses import dataclass, field
+from dataclasses import dataclass
+from dataclasses import field
+from typing import Any
+from typing import cast
+
+import pytest
 
 from hooked_containers import events as e
 from hooked_containers.mapping import HookedMapping
+from hooked_containers.mixins import ContainerMixin
+from hooked_containers.mixins import ListMixin
+from hooked_containers.mixins import MutableMappingMixin
+from hooked_containers.mixins import MutableSetMixin
+
+
+@pytest.mark.parametrize(
+    ("mixin", "storage", "method", "arguments", "expected"),
+    [
+        (ListMixin, [1], "append", (2,), e.Change("add", 1, 2)),
+        (MutableMappingMixin, {"a": 1}, "update", ({"b": 2},), e.Change("add", "b", 2)),
+        (MutableSetMixin, {1}, "add", (2,), e.Change("add", None, 2)),
+    ],
+)
+def test_direct_mixin_composition(mixin, storage, method, arguments, expected):
+    custom_type = type("CustomContainer", (mixin,), {})
+    container = custom_type()
+    changes = []
+    container._storage = storage.copy()
+    container.hook = changes.append
+
+    assert isinstance(container, ContainerMixin)
+    assert len(container) == 1
+    assert list(container) == list(storage)
+    assert next(iter(storage)) in container
+    assert repr(container) == f"CustomContainer({storage!r})"
+    assert changes == []
+
+    getattr(container, method)(*arguments)
+    assert changes == [expected]
+    assert len(container) == 2
+    assert len(storage) == 1
 
 
 @dataclass
 class HookTracker:
-    added: list[e.AddItemEvent] = field(default_factory=list)
-    set: list[e.SetItemEvent] = field(default_factory=list)
-    removed: list[e.RemoveItemEvent] = field(default_factory=list)
+    added: list[object] = field(default_factory=list)
+    set: list[object] = field(default_factory=list)
+    removed: list[object] = field(default_factory=list)
 
-    def hook(self, event: e.ChangeEvent):
-        match event:
-            case e.AddItemEvent():
-                self.added.append(event.item)
-            case e.SetItemEvent():
-                self.set.append(event.item)
-            case e.RemoveItemEvent():
-                self.removed.append(event.item)
+    def hook(self, event: e.Change):
+        match event.operation:
+            case "add":
+                self.added.append(event.value)
+            case "set":
+                self.set.append(event.value)
+            case "remove":
+                self.removed.append(event.value)
 
 
 class TestHookedMapping:
     class TestConstruction:
         def test_empty(self):
             m = HookedMapping({})
-            assert m._data == {}
+            assert m._storage == {}
             assert dict(m) == {}
 
         def test_with_existing(self):
             existing = {"a": 1, "b": 2}
-            og_id = id(existing)
             m = HookedMapping(existing)
-            assert id(m._data) == og_id
+            assert m._storage is not existing
             assert dict(m) == existing
 
         def test_nesting(self):
@@ -41,20 +77,32 @@ class TestHookedMapping:
             assert dict(m["a"]) == {"x": 1}
             assert dict(m["b"]) == {"y": 2}
 
+        def test_recreation_copies_storage_without_duplicate_hooks(self):
+            original_tracker = HookTracker()
+            tracker = HookTracker()
+            original = HookedMapping({"a": 1}, original_tracker.hook)
+            m = HookedMapping(original, tracker.hook)
+
+            assert m._storage is not original._storage
+            m["a"] = 2
+            assert original._storage == {"a": 1}
+            assert tracker.set == [2]
+            assert original_tracker.set == []
+
     class TestMappingOps:
         def test_setitem(self):
             tracker = HookTracker()
             m = HookedMapping({}, tracker.hook)
             m["a"] = 1
-            assert m._data == {"a": 1}
+            assert m._storage == {"a": 1}
             assert tracker.added == [1]
 
-        def test_nested_setitem(self):
+        def test_nested_values_are_not_observed(self):
             tracker = HookTracker()
             m = HookedMapping({"a": {}}, tracker.hook)
             m["a"]["x"] = 1
-            assert m._data == {"a": {"x": 1}}
-            assert tracker.added == [1]
+            assert m._storage == {"a": {"x": 1}}
+            assert tracker.added == []
 
         def test_getitem(self):
             m = HookedMapping({"a": 1})
@@ -64,5 +112,121 @@ class TestHookedMapping:
             tracker = HookTracker()
             m = HookedMapping({"a": 1}, tracker.hook)
             del m["a"]
-            assert not m["a"]
+            with pytest.raises(KeyError):
+                m["a"]
             assert tracker.removed == [1]
+
+        def test_inherited_mutation_helpers(self):
+            tracker = HookTracker()
+            m = HookedMapping({"a": 1}, tracker.hook)
+
+            m.update({"a": 2, "b": 3})
+            assert tracker.set == [2]
+            assert tracker.added == [3]
+            assert m.pop("b") == 3
+            assert tracker.removed == [3]
+            assert m._storage == {"a": 2}
+
+        def test_assignment_returns_none_and_reports_key(self):
+            changes = []
+            m = HookedMapping({"a": 1}, changes.append)
+
+            assert m.__setitem__("a", 2) is None
+            assert m.__setitem__("b", 3) is None
+            assert changes == [e.Change("set", "a", 2), e.Change("add", "b", 3)]
+
+        def test_assign_hooked_mapping(self):
+            changes = []
+            m = HookedMapping({}, changes.append)
+            value = HookedMapping({"x": 1})
+
+            assert m.__setitem__("a", value) is None
+            assert m["a"] is value
+            assert len(changes) == 1
+            assert changes[0].operation == "add"
+            assert changes[0].value is value
+
+        def test_shallow_value_identity(self):
+            changes = []
+            m = HookedMapping({"a": {"x": 1}}, changes.append)
+
+            m["a"]["x"] = 2
+            del m["a"]["x"]
+            assert changes == []
+            value = m["a"]
+            del m["a"]
+            assert changes == [e.Change("remove", "a", {})]
+            assert changes[0].value is value
+
+    def test_reads_views_and_missing_keys_do_not_mutate(self):
+        changes = []
+        mapping = HookedMapping({"a": 1}, changes.append)
+        keys = mapping.keys()
+        assert mapping.get("missing", 9) == 9
+        assert mapping.pop("missing", 9) == 9
+        with pytest.raises(KeyError):
+            mapping["missing"]
+        with pytest.raises(KeyError):
+            del mapping["missing"]
+        assert changes == []
+        assert list(mapping.items()) == [("a", 1)]
+        mapping["b"] = 2
+        assert list(keys) == ["a", "b"]
+        assert list(mapping.values()) == [1, 2]
+        assert list(reversed(mapping)) == ["b", "a"]
+
+    def test_native_order_copy_and_merge(self):
+        changes = []
+        mapping = HookedMapping([("a", 1), ("b", 2)], changes.append, c=3)
+        assert mapping == {"a": 1, "b": 2, "c": 3}
+        assert mapping.popitem() == ("c", 3)
+        assert changes == [e.Change("remove", "c", 3)]
+        changes.clear()
+        assert type(mapping.copy()) is dict
+        assert mapping | {"a": 9} == {"a": 9, "b": 2}
+        assert {"a": 9} | mapping == {"a": 1, "b": 2}
+        assert changes == []
+        original = mapping
+        mapping |= [("b", 4), ("c", 5)]
+        assert mapping is original
+        assert changes == [e.Change("set", "b", 4), e.Change("add", "c", 5)]
+
+    def test_update_duck_mapping_and_partial_failure(self):
+        class KeysOnly:
+            def keys(self):
+                return ["a"]
+
+            def __getitem__(self, _key):
+                return 1
+
+        changes = []
+        mapping = HookedMapping(hook=changes.append)
+        mapping.update(KeysOnly())
+        with pytest.raises(ValueError):
+            mapping.update(cast(Any, [("b", 2), ("bad",)]))
+        assert mapping == {"a": 1, "b": 2}
+        assert changes == [e.Change("add", "a", 1), e.Change("add", "b", 2)]
+
+    def test_clear_and_setdefault(self):
+        changes = []
+        mapping = HookedMapping[str | None, int]({None: 1}, changes.append)
+        assert mapping.setdefault(None, 9) == 1
+        assert changes == []
+        assert mapping.setdefault("a", 2) == 2
+        assert changes == [e.Change("add", "a", 2)]
+        changes.clear()
+        mapping.clear()
+        assert mapping == {}
+        assert changes == [e.Change("remove", "a", 2), e.Change("remove", None, 1)]
+        changes.clear()
+        mapping.clear()
+        assert changes == []
+
+    def test_callback_error_leaves_write_in_place(self):
+        def fail(_change):
+            raise RuntimeError("callback failed")
+
+        mapping = HookedMapping(hook=fail)
+        with pytest.raises(RuntimeError, match="callback failed"):
+            mapping["a"] = 1
+        assert mapping == {"a": 1}

tests/test_sequence.py

@@ -1,12 +1,20 @@
 from __future__ import annotations
 
+from collections.abc import Mapping
+from collections.abc import MutableMapping
+from collections.abc import MutableSequence
+from collections.abc import MutableSet
 from typing import Any
 
+import pytest
+
+from hooked_containers import events as e
+from hooked_containers.mapping import HookedMapping
+from hooked_containers.mixins import ListMixin
+from hooked_containers.mixins import MutableMappingMixin
+from hooked_containers.mixins import MutableSetMixin
 from hooked_containers.sequence import HookedList
-
-
-def get_id(a: Any):
-    return str(hex(id(a)))
+from hooked_containers.set import HookedSet
 
 
 class TestHookedList:
@@ -21,13 +29,26 @@ class TestHookedList:
 
         def test_recreation(self):
             initial = [1, 2, 3]
-            initial_id = id(initial)
 
             lst = HookedList(initial)
-            assert id(lst._data) == initial_id
+            assert lst._storage is not initial
 
             lst2 = HookedList(lst)
-            assert id(lst2._data) == initial_id
+            assert lst2._storage is not lst._storage
+            assert lst2 == initial
+
+        def test_recreation_does_not_duplicate_hooks(self):
+            original_changes = []
+            changes = []
+            original = HookedList([1], original_changes.append)
+            lst = HookedList(original, changes.append)
+
+            lst.append(2)
+            assert lst._storage is not original._storage
+            assert original._storage == [1]
+            assert original_changes == []
+            assert len(changes) == 1
+            assert changes == [e.Change("add", 1, 2)]
 
     class TestSeqOps:
         def test_len(self):
@@ -53,16 +74,16 @@ class TestHookedList:
     class TestMutableOps:
         def test_setitem(self):
             added = []
-            lst = HookedList(
+            lst = HookedList[Any](
                 [1, 2, [4, 5, [6, 7]]],
-                lambda e: added.append(e.item),
+                lambda event: added.append(event.value),
             )
             lst[0] = 10
             lst.append(20)
             assert added == [10, 20]
 
             lst[2][-1].append(8)
-            assert added == [10, 20, 8]
+            assert added == [10, 20]
 
         def test_delitem(self):
             lst = HookedList([1, 2, 3])
@@ -73,3 +94,194 @@ class TestHookedList:
             lst = HookedList([1, 3])
             lst.insert(1, 2)
             assert list(lst) == [1, 2, 3]
+
+        def test_inherited_mutation_helpers(self):
+            changes = []
+            lst = HookedList([1], changes.append)
+
+            lst.extend([2, 3])
+            assert lst.pop() == 3
+            lst.remove(1)
+            assert list(lst) == [2]
+            assert changes == [
+                e.Change("add", 1, 2),
+                e.Change("add", 2, 3),
+                e.Change("remove", 2, 3),
+                e.Change("remove", 0, 1),
+            ]
+
+        def test_slice_mutations(self):
+            changes = []
+            lst = HookedList([1, 2, 3], changes.append)
+
+            lst[1:3] = iter([4, 5])
+            assert list(lst) == [1, 4, 5]
+            del lst[::2]
+            assert list(lst) == [4]
+            assert changes == [
+                e.Change("set", slice(1, 3), [4, 5]),
+                e.Change("remove", slice(None, None, 2), [1, 5]),
+            ]
+
+        def test_failed_mutations_do_not_notify(self):
+            changes = []
+            lst = HookedList([1, 2, 3], changes.append)
+
+            with pytest.raises(ValueError):
+                lst[::2] = [4]
+            with pytest.raises(IndexError):
+                del lst[10]
+            assert list(lst) == [1, 2, 3]
+            assert changes == []
+
+        def test_nested_values_are_not_observed(self):
+            changes = []
+            lst = HookedList([[1]], changes.append)
+            nested = lst[0]
+
+            nested[0] = 2
+            nested.insert(1, 3)
+            del nested[0]
+            assert lst._storage == [[3]]
+            assert changes == []
+
+    def test_native_comparisons_and_non_mutating_results(self):
+        changes = []
+        items = HookedList([1, 2], changes.append)
+        assert items == [1, 2]
+        native = [1, 2]
+        assert native == items
+        assert items != (1, 2)
+        assert items < [1, 3]
+        assert items <= HookedList([1, 2])
+        assert items > [0]
+        assert items >= [1, 2]
+        with pytest.raises(TypeError):
+            assert items < (1, 3)
+        with pytest.raises(TypeError):
+            _ = items + (3,)
+        for result in (items[:], items.copy(), items + [3], [0] + items, items * 2, 2 * items):
+            assert type(result) is list
+            result.append(99)
+        assert items == [1, 2]
+        assert changes == []
+
+    def test_index_protocol_and_normalized_indices(self):
+        class Index:
+            def __index__(self):
+                return -1
+
+        changes = []
+        items = HookedList([1, 2], changes.append)
+        assert items[Index()] == 2
+        items[Index()] = 3
+        items.insert(-100, 0)
+        items.insert(100, 4)
+        del items[Index()]
+        assert items == [0, 1, 3]
+        assert changes == [
+            e.Change("set", 1, 3),
+            e.Change("add", 0, 0),
+            e.Change("add", 3, 4),
+            e.Change("remove", 3, 4),
+        ]
+
+    def test_self_extension_and_in_place_repetition(self):
+        changes = []
+        items = HookedList([1, 2], changes.append)
+        original = items
+        items += items
+        assert items is original
+        assert items == [1, 2, 1, 2]
+        assert changes == [e.Change("add", 2, 1), e.Change("add", 3, 2)]
+        changes.clear()
+        items *= 2
+        assert items is original
+        assert items == [1, 2] * 4
+        assert changes == [e.Change("set", slice(None), [1, 2] * 4)]
+        changes.clear()
+        items *= 1
+        assert changes == []
+        items *= 0
+        assert items == []
+        assert changes == [e.Change("set", slice(None), [])]
+
+    def test_reverse_sort_and_empty_writes(self):
+        changes = []
+        items = HookedList([3, 1, 2], changes.append)
+        items.reverse()
+        assert items == [2, 1, 3]
+        assert changes == [e.Change("set", 0, 2), e.Change("set", 2, 3)]
+        changes.clear()
+        items.sort(reverse=True)
+        assert items == [3, 2, 1]
+        assert changes == [e.Change("set", slice(None), [3, 2, 1])]
+        changes.clear()
+        del items[0:0]
+        items[0:0] = []
+        items.extend([])
+        assert changes == []
+        items.clear()
+        assert [change.value for change in changes] == [1, 2, 3]
+        changes.clear()
+        items.clear()
+        items.reverse()
+        items.sort()
+        assert changes == []
+
+    def test_partial_extend_and_sort_failure(self):
+        def values():
+            yield 2
+            raise RuntimeError("iteration failed")
+
+        changes = []
+        items = HookedList([1], changes.append)
+        with pytest.raises(RuntimeError, match="iteration failed"):
+            items.extend(values())
+        assert items == [1, 2]
+        assert changes == [e.Change("add", 1, 2)]
+        changes.clear()
+
+        def fail(_value):
+            raise ValueError("key failed")
+
+        with pytest.raises(ValueError, match="key failed"):
+            items.sort(key=fail)
+        assert items == [1, 2]
+        assert changes == []
+
+
+@pytest.mark.parametrize(
+    ("mixin", "factory", "mutate", "expected"),
+    [
+        (MutableMappingMixin, dict, lambda container: container.update(a=1), e.Change("add", "a", 1)),
+        (ListMixin, list, lambda container: container.append(1), e.Change("add", 0, 1)),
+        (MutableSetMixin, set, lambda container: container.add(1), e.Change("add", None, 1)),
+    ],
+)
+def test_mixins_work_without_concrete_wrappers(mixin, factory, mutate, expected):
+    class Custom(mixin):
+        def __init__(self):
+            self._storage = factory()
+
+    changes = []
+    container = Custom()
+    container.hook = changes.append
+    mutate(container)
+    assert changes == [expected]
+
+
+def test_helpers_are_inherited_from_standard_abcs():
+    assert HookedList.append is MutableSequence.append
+    assert HookedList.extend is MutableSequence.extend
+    assert HookedList.reverse is MutableSequence.reverse
+    assert HookedList.__iadd__ is MutableSequence.__iadd__
+    assert HookedMapping.get is Mapping.get
+    assert HookedMapping.keys is Mapping.keys
+    assert HookedMapping.update is MutableMapping.update
+    assert HookedSet.pop is MutableSet.pop
+    assert HookedSet.remove is MutableSet.remove
+    assert HookedSet.__ior__ is MutableSet.__ior__
+    assert HookedSet.__iand__ is MutableSet.__iand__
+    assert HookedSet.__ixor__ is MutableSet.__ixor__
+    assert HookedSet.__isub__ is MutableSet.__isub__

tests/test_set.py

@@ -0,0 +1,184 @@
+from dataclasses import FrozenInstanceError
+from typing import Any
+from typing import cast
+
+import pytest
+
+from hooked_containers import Change
+from hooked_containers import HookedSet
+
+
+class TestHookedSet:
+    def test_construction_and_owned_storage(self):
+        changes = []
+        original = {1, 2}
+        members = HookedSet(original, changes.append)
+        assert members == original
+        assert members._storage is not original
+        assert HookedSet([1, 1, 2]) == {1, 2}
+        assert HookedSet() == set()
+        recreated = HookedSet(members)
+        assert recreated._storage is not members._storage
+        assert changes == []
+        members.add(3)
+        assert original == {1, 2}
+        assert recreated == {1, 2}
+
+    def test_add_discard_and_no_ops(self):
+        changes = []
+        members = HookedSet[str](hook=changes.append)
+        members.add("a")
+        members.add("a")
+        members.discard("missing")
+        members.discard("a")
+        assert changes == [Change("add", None, "a"), Change("remove", None, "a")]
+        changes.clear()
+        members.clear()
+        members.update([])
+        members.difference_update([])
+        assert changes == []
+
+    def test_remove_pop_and_clear(self):
+        changes = []
+        members = HookedSet([1, 2], changes.append)
+        members.remove(1)
+        assert members.pop() == 2
+        assert changes == [Change("remove", None, 1), Change("remove", None, 2)]
+        changes.clear()
+        with pytest.raises(KeyError):
+            members.remove(3)
+        with pytest.raises(KeyError):
+            members.pop()
+        assert changes == []
+        members.update([3, 4])
+        changes.clear()
+        members.clear()
+        assert members == set()
+        assert {change.value for change in changes} == {3, 4}
+        assert all(change.operation == "remove" and change.key is None for change in changes)
+
+    def test_removal_reports_stored_value(self):
+        changes = []
+        members = HookedSet([1], changes.append)
+        members.discard(True)
+        assert changes == [Change("remove", None, 1)]
+        assert type(changes[0].value) is int
+
+    def test_hashability_is_validated_before_no_op_detection(self):
+        changes = []
+        members = HookedSet([frozenset({1})], changes.append)
+        with pytest.raises(TypeError):
+            members.add(cast(Any, {1}))
+        assert members == {frozenset({1})}
+        assert changes == []
+        members.discard(cast(Any, {1}))
+        assert members == set()
+        assert changes == [Change("remove", None, frozenset({1}))]
+
+    def test_algebra_and_named_helpers_do_not_notify(self):
+        changes = []
+        members = HookedSet([1, 2], changes.append)
+        assert members == {1, 2}
+        assert members <= {1, 2, 3}
+        assert members < {1, 2, 3}
+        assert members >= {1}
+        assert members > {1}
+        assert members != {1}
+        assert members.isdisjoint([3, 4])
+        assert members.issubset([1, 2, 3])
+        assert members.issuperset([1])
+        results = [
+            (members | {2, 3}, {1, 2, 3}),
+            (members & {2, 3}, {2}),
+            (members - {2, 3}, {1}),
+            (members ^ {2, 3}, {1, 3}),
+            ({3} | members, {1, 2, 3}),
+            ({2, 3} & members, {2}),
+            ({2, 3} - members, {3}),
+            ({2, 3} ^ members, {1, 3}),
+            (members.union([3], [4]), {1, 2, 3, 4}),
+            (members.intersection([2, 3]), {2}),
+            (members.difference([2], [3]), {1}),
+            (members.symmetric_difference([2, 3]), {1, 3}),
+            (members.copy(), {1, 2}),
+        ]
+        for result, expected in results:
+            assert result == expected
+            assert type(result) is set
+            result.add(99)
+        assert members == {1, 2}
+        assert changes == []
+
+    def test_abc_operators_accept_iterables(self):
+        members = HookedSet([1, 2])
+        assert members | cast(Any, [3]) == {1, 2, 3}
+        assert members & cast(Any, [2]) == {2}
+        members |= cast(Any, [3])
+        assert members == {1, 2, 3}
+
+    @pytest.mark.parametrize("operation", ["union", "intersection", "difference", "symmetric_difference"])
+    def test_in_place_operations_keep_identity_and_notify(self, operation):
+        changes = []
+        members = HookedSet([1, 2], changes.append)
+        original = members
+        if operation == "union":
+            members |= {2, 3}
+            expected = {1, 2, 3}
+            expected_changes = {("add", 3)}
+        elif operation == "intersection":
+            members &= {2, 3}
+            expected = {2}
+            expected_changes = {("remove", 1)}
+        elif operation == "difference":
+            members -= {2, 3}
+            expected = {1}
+            expected_changes = {("remove", 2)}
+        else:
+            members ^= {2, 3}
+            expected = {1, 3}
+            expected_changes = {("remove", 2), ("add", 3)}
+        assert members is original
+        assert members == expected
+        assert {(change.operation, change.value) for change in changes} == expected_changes
+        assert all(change.key is None for change in changes)
+
+    def test_named_updates_and_self_aliases(self):
+        members = HookedSet([1, 2])
+        members.update([2, 3], [4])
+        assert members == {1, 2, 3, 4}
+        members.intersection_update([2, 3, 4], [3, 4])
+        assert members == {3, 4}
+        members.symmetric_difference_update([4, 5, 5])
+        assert members == {3, 5}
+        members.difference_update([3], [9])
+        assert members == {5}
+        members.update(members)
+        members.intersection_update(members)
+        assert members == {5}
+        members.symmetric_difference_update(members)
+        assert members == set()
+        members.update([1, 2])
+        members.difference_update(members)
+        assert members == set()
+
+    def test_partial_update_failure_is_observed(self):
+        def values():
+            yield 1
+            raise RuntimeError("iteration failed")
+
+        changes = []
+        members = HookedSet[int](hook=changes.append)
+        with pytest.raises(RuntimeError, match="iteration failed"):
+            members.update(values())
+        assert members == {1}
+        assert changes == [Change("add", None, 1)]
+
+
+def test_change_metadata_is_immutable_and_values_are_shallow():
+    value = []
+    change = Change("set", "key", value)
+    with pytest.raises(FrozenInstanceError):
+        cast(Any, change).key = "other"
+    value.append(1)
+    assert change.value is value
+    assert change.value == [1]