Deprecate subclassing dict

docs/source/structured_config.rst

@@ -99,6 +99,8 @@ You can create a config with specified fields that can also accept arbitrary val
     >>> conf.foo = "bar"
     >>> assert conf.foo == "bar"
 
+This feature is deprecated; OmegaConf's ability to handle structured configs
+that subclass ``Dict`` is planned to be removed in a future release.
 
 
 Static type checker support

omegaconf/_utils.py

@@ -3,6 +3,7 @@
 import re
 import string
 import sys
+import warnings
 from contextlib import contextmanager
 from enum import Enum
 from textwrap import dedent
@@ -234,10 +235,17 @@ def extract_dict_subclass_data(obj: Any, parent: Any) -> Optional[Dict[str, Any]
     """Check if obj is an instance of a subclass of Dict. If so, extract the Dict keys/values."""
     from omegaconf.omegaconf import _maybe_wrap
 
+    obj_type = type(obj)
+    if is_dict_subclass(obj) or is_dict_subclass(obj_type):
+        warnings.warn(
+            "Subclassing of `Dict` by Structured Config classes is deprecated",
+            UserWarning,
+            stacklevel=2,
+        )
+
     if isinstance(obj, type):
         return None
 
-    obj_type = type(obj)
     if is_dict_subclass(obj_type):
         dict_subclass_data = {}
         key_type, element_type = get_dict_key_value_types(obj_type)

tests/structured_conf/test_structured_config.py

@@ -1,8 +1,9 @@
+import re
 import sys
 from importlib import import_module
 from typing import Any, Dict, List, Optional
 
-from pytest import fixture, mark, param, raises
+from pytest import fixture, mark, param, raises, warns
 
 from omegaconf import (
     MISSING,
@@ -932,8 +933,17 @@ def test_dataclass_frozen() -> None:
 
 
 class TestDictSubclass:
+    def warns_deprecated(self) -> Any:
+        return warns(
+            UserWarning,
+            match=re.escape(
+                "Subclassing of `Dict` by Structured Config classes is deprecated"
+            ),
+        )
+
     def test_str2str(self, module: Any) -> None:
-        cfg = OmegaConf.structured(module.DictSubclass.Str2Str())
+        with self.warns_deprecated():
+            cfg = OmegaConf.structured(module.DictSubclass.Str2Str())
         cfg.hello = "world"
         assert cfg.hello == "world"
 
@@ -943,7 +953,8 @@ def test_str2str(self, module: Any) -> None:
     def test_dict_subclass_data_preserved_upon_node_creation(self, module: Any) -> None:
         src = module.DictSubclass.Str2StrWithField()
         src["baz"] = "qux"
-        cfg = OmegaConf.structured(src)
+        with self.warns_deprecated():
+            cfg = OmegaConf.structured(src)
         assert cfg.foo == "bar"
         assert cfg.baz == "qux"
 
@@ -954,7 +965,8 @@ def test_create_dict_subclass_with_bad_value_type(self, module: Any) -> None:
             OmegaConf.structured(src)
 
     def test_str2str_as_sub_node(self, module: Any) -> None:
-        cfg = OmegaConf.create({"foo": module.DictSubclass.Str2Str})
+        with self.warns_deprecated():
+            cfg = OmegaConf.create({"foo": module.DictSubclass.Str2Str})
         assert OmegaConf.get_type(cfg.foo) == module.DictSubclass.Str2Str
         assert _utils.get_ref_type(cfg.foo) == Any
 
@@ -968,7 +980,8 @@ def test_str2str_as_sub_node(self, module: Any) -> None:
             cfg.foo[123] = "fail"
 
     def test_int2str(self, module: Any) -> None:
-        cfg = OmegaConf.structured(module.DictSubclass.Int2Str())
+        with self.warns_deprecated():
+            cfg = OmegaConf.structured(module.DictSubclass.Int2Str())
 
         cfg[10] = "ten"  # okay
         assert cfg[10] == "ten"
@@ -986,7 +999,8 @@ def test_int2str(self, module: Any) -> None:
             cfg[Color.RED] = "fail"
 
     def test_int2str_as_sub_node(self, module: Any) -> None:
-        cfg = OmegaConf.create({"foo": module.DictSubclass.Int2Str})
+        with self.warns_deprecated():
+            cfg = OmegaConf.create({"foo": module.DictSubclass.Int2Str})
         assert OmegaConf.get_type(cfg.foo) == module.DictSubclass.Int2Str
         assert _utils.get_ref_type(cfg.foo) == Any
 
@@ -1006,7 +1020,8 @@ def test_int2str_as_sub_node(self, module: Any) -> None:
             cfg.foo[Color.RED] = "fail"
 
     def test_color2str(self, module: Any) -> None:
-        cfg = OmegaConf.structured(module.DictSubclass.Color2Str())
+        with self.warns_deprecated():
+            cfg = OmegaConf.structured(module.DictSubclass.Color2Str())
         cfg[Color.RED] = "red"
 
         with raises(KeyValidationError):
@@ -1016,7 +1031,8 @@ def test_color2str(self, module: Any) -> None:
             cfg[123] = "nope"
 
     def test_color2color(self, module: Any) -> None:
-        cfg = OmegaConf.structured(module.DictSubclass.Color2Color())
+        with self.warns_deprecated():
+            cfg = OmegaConf.structured(module.DictSubclass.Color2Color())
 
         # add key
         cfg[Color.RED] = "GREEN"
@@ -1045,7 +1061,8 @@ def test_color2color(self, module: Any) -> None:
             cfg.greeen = "nope"
 
     def test_str2user(self, module: Any) -> None:
-        cfg = OmegaConf.structured(module.DictSubclass.Str2User())
+        with self.warns_deprecated():
+            cfg = OmegaConf.structured(module.DictSubclass.Str2User())
 
         cfg.bond = module.User(name="James Bond", age=7)
         assert cfg.bond.name == "James Bond"
@@ -1060,7 +1077,8 @@ def test_str2user(self, module: Any) -> None:
             cfg[Color.BLUE] = "nope"
 
     def test_str2str_with_field(self, module: Any) -> None:
-        cfg = OmegaConf.structured(module.DictSubclass.Str2StrWithField())
+        with self.warns_deprecated():
+            cfg = OmegaConf.structured(module.DictSubclass.Str2StrWithField())
         assert cfg.foo == "bar"
         cfg.hello = "world"
         assert cfg.hello == "world"
@@ -1074,10 +1092,13 @@ def test_usr2str(self, module: Any) -> None:
                 OmegaConf.structured(module.DictSubclass.Error.User2Str())
 
         def test_str2int_with_field_of_different_type(self, module: Any) -> None:
-            cfg = OmegaConf.structured(module.DictSubclass.Str2IntWithStrField())
+            with warns(UserWarning):
+                cfg = OmegaConf.structured(module.DictSubclass.Str2IntWithStrField())
             with raises(ValidationError):
                 cfg.foo = "str"
 
+
+class TestConfigs2:
     def test_construct_from_another_retain_node_types(self, module: Any) -> None:
         cfg1 = OmegaConf.create(module.User(name="James Bond", age=7))
         with raises(ValidationError):