Add support for __slots__

mashumaro/serializer/base/dict.py

@@ -6,6 +6,8 @@
 
 
 class DataClassDictMixin:
+    __slots__ = ()
+
     def __init_subclass__(cls: Type[T], **kwargs):
         builder = CodeBuilder(cls)
         exc = None

mashumaro/serializer/json.py

@@ -26,6 +26,8 @@ def __call__(self, s: EncodedData, **kwargs) -> Dict[Any, Any]:
 
 
 class DataClassJSONMixin(DataClassDictMixin):
+    __slots__ = ()
+
     def to_json(
         self: T,
         encoder: Encoder = json.dumps,

mashumaro/serializer/msgpack.py

@@ -27,6 +27,8 @@ def __call__(self, packed: EncodedData, **kwargs) -> Dict[Any, Any]:
 
 
 class DataClassMessagePackMixin(DataClassDictMixin):
+    __slots__ = ()
+
     def to_msgpack(
         self: T,
         encoder: Encoder = partial(msgpack.packb, use_bin_type=True),

mashumaro/serializer/yaml.py

@@ -26,6 +26,8 @@ def __call__(self, packed: EncodedData, **kwargs) -> Dict[Any, Any]:
 
 
 class DataClassYAMLMixin(DataClassDictMixin):
+    __slots__ = ()
+
     def to_yaml(
         self: T,
         encoder: Encoder = yaml.dump,  # type: ignore

tests/test_aliases.py

@@ -5,9 +5,9 @@
 
 from mashumaro import DataClassDictMixin
 from mashumaro.config import (
-    BaseConfig,
     TO_DICT_ADD_BY_ALIAS_FLAG,
     TO_DICT_ADD_OMIT_NONE_FLAG,
+    BaseConfig,
 )
 from mashumaro.exceptions import MissingField
 

tests/test_common.py

@@ -0,0 +1,52 @@
+from dataclasses import dataclass
+
+import pytest
+
+from mashumaro import (
+    DataClassDictMixin,
+    DataClassJSONMixin,
+    DataClassMessagePackMixin,
+    DataClassYAMLMixin,
+)
+
+
+def test_slots():
+    @dataclass
+    class RegularDataClass:
+        __slots__ = ("number",)
+        number: int
+
+    @dataclass
+    class DictDataClass(DataClassDictMixin):
+        __slots__ = ("number",)
+        number: int
+
+    @dataclass
+    class JSONDataClass(DataClassJSONMixin):
+        __slots__ = ("number",)
+        number: int
+
+    @dataclass
+    class MessagePackDataClass(DataClassMessagePackMixin):
+        __slots__ = ("number",)
+        number: int
+
+    @dataclass
+    class YAMLDataClass(DataClassYAMLMixin):
+        __slots__ = ("number",)
+        number: int
+
+    for cls in (
+        RegularDataClass,
+        DictDataClass,
+        JSONDataClass,
+        MessagePackDataClass,
+        YAMLDataClass,
+    ):
+        instance = cls(1)
+        with pytest.raises(AttributeError) as e:
+            instance.new_attribute = 2
+        assert (
+            str(e.value)
+            == f"'{cls.__name__}' object has no attribute 'new_attribute'"
+        )

tests/test_config.py

@@ -4,10 +4,7 @@
 import pytest
 
 from mashumaro import DataClassDictMixin
-from mashumaro.config import (
-    TO_DICT_ADD_OMIT_NONE_FLAG,
-    BaseConfig,
-)
+from mashumaro.config import TO_DICT_ADD_OMIT_NONE_FLAG, BaseConfig
 from mashumaro.types import SerializationStrategy
 
 from .entities import (