ENH correctly restore default_factory of a defaultdict

docs/changes.rst

@@ -9,8 +9,13 @@ skops Changelog
     :depth: 1
     :local:
 
+v0.11
+-----
+- Correctly restore ``default_factory`` when saving and loading a ``defaultdict``.
+  :pr:`433` by `Adrin Jalali`_.
+
 v0.10
-----
+-----
 - Removes Pythn 3.8 support and adds Python 3.12 Support :pr:`418` by :user:`Thomas Lazarus <lazarust>`.
 - Removes a shortcut to add `sklearn-intelex` as a not dependency.
   :pr:`420` by :user:`Thomas Lazarus < lazarust > `.

skops/__init__.py

@@ -16,7 +16,7 @@
 # Dev branch marker is: 'X.Y.dev' or 'X.Y.devN' where N is an integer.
 # 'X.Y.dev0' is the canonical version of 'X.Y.dev'
 #
-__version__ = "0.10.dev0"
+__version__ = "0.11.dev0"
 
 try:
     # This variable is injected in the __builtins__ by the build

skops/io/_general.py

@@ -4,6 +4,7 @@
 import json
 import operator
 import uuid
+from collections import defaultdict
 from functools import partial
 from reprlib import Repr
 from types import FunctionType, MethodType
@@ -14,6 +15,7 @@
 from ._audit import Node, get_tree
 from ._protocol import PROTOCOL
 from ._trusted_types import (
+    BUILTIN_TYPE_NAMES,
     NUMPY_DTYPE_TYPE_NAMES,
     NUMPY_UFUNC_TYPE_NAMES,
     PRIMITIVE_TYPE_NAMES,
@@ -63,7 +65,7 @@ def __init__(
         trusted: Optional[Sequence[str]] = None,
     ) -> None:
         super().__init__(state, load_context, trusted)
-        self.trusted = self._get_trusted(trusted, [dict])
+        self.trusted = self._get_trusted(trusted, [dict, "collections.OrderedDict"])
         self.children = {
             "key_types": get_tree(state["key_types"], load_context, trusted=trusted),
             "content": {
@@ -80,6 +82,45 @@ def _construct(self):
         return content
 
 
+def defaultdict_get_state(obj: Any, save_context: SaveContext) -> dict[str, Any]:
+    res = {
+        "__class__": obj.__class__.__name__,
+        "__module__": get_module(type(obj)),
+        "__loader__": "DefaultDictNode",
+    }
+    content = {}
+    # explicitly pass a dict object instead of _DictWithDeprecatedKeys and
+    # later construct a _DictWithDeprecatedKeys object.
+    content["main"] = get_state(dict(obj), save_context)
+    content["default_factory"] = get_state(obj.default_factory, save_context)
+    res["content"] = content
+    return res
+
+
+class DefaultDictNode(Node):
+    def __init__(
+        self,
+        state: dict[str, Any],
+        load_context: LoadContext,
+        trusted: Optional[Sequence[str]] = None,
+    ) -> None:
+        super().__init__(state, load_context, trusted)
+        self.trusted = ["collections.defaultdict"]
+        self.children = {
+            "main": get_tree(state["content"]["main"], load_context, trusted=trusted),
+            "default_factory": get_tree(
+                state["content"]["default_factory"],
+                load_context,
+                trusted=trusted,
+            ),
+        }
+
+    def _construct(self):
+        instance = defaultdict(**self.children["main"].construct())
+        instance.default_factory = self.children["default_factory"].construct()
+        return instance
+
+
 def list_get_state(obj: Any, save_context: SaveContext) -> dict[str, Any]:
     res = {
         "__class__": obj.__class__.__name__,
@@ -298,7 +339,7 @@ def __init__(
         super().__init__(state, load_context, trusted)
         # TODO: what do we trust?
         self.trusted = self._get_trusted(
-            trusted, PRIMITIVE_TYPE_NAMES + NUMPY_DTYPE_TYPE_NAMES
+            trusted, PRIMITIVE_TYPE_NAMES + BUILTIN_TYPE_NAMES + NUMPY_DTYPE_TYPE_NAMES
         )
         # We use a bare Node type here since a Node only checks the type in the
         # dict using __class__ and __module__ keys.
@@ -597,6 +638,7 @@ def _construct(self):
 # tuples of type and function that gets the state of that type
 GET_STATE_DISPATCH_FUNCTIONS = [
     (dict, dict_get_state),
+    (defaultdict, defaultdict_get_state),
     (list, list_get_state),
     (set, set_get_state),
     (tuple, tuple_get_state),
@@ -616,6 +658,7 @@ def _construct(self):
 
 NODE_TYPE_MAPPING = {
     ("DictNode", PROTOCOL): DictNode,
+    ("DefaultDictNode", PROTOCOL): DefaultDictNode,
     ("ListNode", PROTOCOL): ListNode,
     ("SetNode", PROTOCOL): SetNode,
     ("TupleNode", PROTOCOL): TupleNode,

skops/io/_trusted_types.py

@@ -10,6 +10,10 @@
 
 PRIMITIVE_TYPE_NAMES = ["builtins." + t.__name__ for t in PRIMITIVES_TYPES]
 
+BUILTIN_TYPES = [list, set, map, tuple]
+
+BUILTIN_TYPE_NAMES = ["builtins." + t.__name__ for t in BUILTIN_TYPES]
+
 SKLEARN_ESTIMATOR_TYPE_NAMES = [
     get_type_name(estimator_class)
     for _, estimator_class in all_estimators()

skops/io/tests/test_external.py

@@ -76,7 +76,7 @@ def lgbm(self):
     def trusted(self):
         # TODO: adjust once more types are trusted by default
         return [
-            "collections.defaultdict",
+            "collections.OrderedDict",
             "lightgbm.basic.Booster",
             "lightgbm.sklearn.LGBMClassifier",
             "lightgbm.sklearn.LGBMRegressor",

skops/io/tests/test_persist.py

@@ -5,7 +5,7 @@
 import operator
 import sys
 import warnings
-from collections import Counter
+from collections import Counter, defaultdict
 from functools import partial, wraps
 from pathlib import Path
 from zipfile import ZIP_DEFLATED, ZipFile
@@ -56,6 +56,7 @@
 from skops.io._audit import NODE_TYPE_MAPPING, get_tree
 from skops.io._sklearn import UNSUPPORTED_TYPES
 from skops.io._trusted_types import (
+    BUILTIN_TYPE_NAMES,
     NUMPY_DTYPE_TYPE_NAMES,
     NUMPY_UFUNC_TYPE_NAMES,
     PRIMITIVE_TYPE_NAMES,
@@ -247,7 +248,7 @@ def _tested_ufuncs():
 
 
 def _tested_types():
-    for full_name in PRIMITIVE_TYPE_NAMES + NUMPY_DTYPE_TYPE_NAMES:
+    for full_name in PRIMITIVE_TYPE_NAMES + NUMPY_DTYPE_TYPE_NAMES + BUILTIN_TYPE_NAMES:
         module_name, _, type_name = full_name.rpartition(".")
         yield gettype(module_name=module_name, cls_or_func=type_name)
 
@@ -396,7 +397,9 @@ def test_can_trust_ufuncs(ufunc):
 
 
 @pytest.mark.parametrize(
-    "type_", _tested_types(), ids=PRIMITIVE_TYPE_NAMES + NUMPY_DTYPE_TYPE_NAMES
+    "type_",
+    _tested_types(),
+    ids=PRIMITIVE_TYPE_NAMES + NUMPY_DTYPE_TYPE_NAMES + BUILTIN_TYPE_NAMES,
 )
 def test_can_trust_types(type_):
     dumped = dumps(type_)
@@ -1078,3 +1081,12 @@ def test_trusted_bool_raises(tmp_path):
 
     with pytest.raises(TypeError, match="trusted must be a list of strings"):
         loads(dumps(10), trusted=True)  # type: ignore
+
+
+def test_defaultdict():
+    """Test that we correctly restore a defaultdict."""
+    obj = defaultdict(set)
+    obj["foo"] = "bar"
+    obj_loaded = loads(dumps(obj))
+    assert obj_loaded == obj
+    assert obj_loaded.default_factory == obj.default_factory