tests passed

LICENSE

@@ -0,0 +1,9 @@
+MIT License
+
+Copyright (c) 2024 Jim Chng <jimchng@outlook.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+1. The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+2. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Makefile

@@ -131,6 +131,9 @@ test-leak:
 test-file:
 	$(PYTHON) -m pytest $(FILE) $(PYTEST_FLAGS)
 
+test-e2e:
+	bash tests/build_test_pyvers_docker_images.sh
+
 # Development workflow targets
 dev: clean build test
 

examples/email_str.py

@@ -1,13 +1,21 @@
+import pytest
+
+
 import re
 
-import pytest
 
 from newtype import NewType, newtype_exclude
 
 
 class EmailStr(NewType(str)):
+    # you can define `__slots__` to save space
+    __slots__ = (
+        '_local_part',
+        '_domain_part',
+    )
+
     def __init__(self, value: str):
-        super().__init__(value)
+        super().__init__()
         if "@" not in value:
             raise TypeError("`EmailStr` requires a '@' symbol within")
         self._local_part, self._domain_part = value.split("@")
@@ -98,6 +106,14 @@ def test_emailstr_properties_methods():
     assert EmailStr.is_valid_email("invalid-email.com") is False
 
 
+def test_email_str__slots__():
+    email = EmailStr("test@example.com")
+
+    with pytest.raises(AttributeError):
+        email.hi = "bye"
+        assert email.hi == "bye"
+
+
 # Run the tests
 if __name__ == "__main__":
     pytest.main([__file__])

newtype/newtype.py

@@ -111,6 +111,18 @@ def func_is_excluded(func):
     return getattr(func, NEWTYPE_EXCLUDE_FUNC_STR, False)
 
 
+def can_subclass_have___slots__(base_type: T) -> bool:
+    try:
+
+        class _Test(base_type):  # type: ignore[valid-type, misc]
+            __slots__ = ("a", "b")
+
+        _Test()
+    except TypeError:
+        return False
+    return True
+
+
 def NewType(base_type: T, **context: "Dict[str, Any]") -> T:  # noqa: N802, C901
     """Create a new type that preserves type information through all operations.
 
@@ -175,6 +187,12 @@ class BaseNewType(base_type):  # type: ignore[valid-type, misc]
                 NEWTYPE_INIT_ARGS_STR,
                 NEWTYPE_INIT_KWARGS_STR,
             )
+        else:
+            if can_subclass_have___slots__(base_type):
+                __slots__ = (
+                    NEWTYPE_INIT_ARGS_STR,
+                    NEWTYPE_INIT_KWARGS_STR,
+                )
 
         def __init_subclass__(cls, **context) -> None:
             """Initialize a subclass of BaseNewType.
@@ -190,8 +208,9 @@ def __init_subclass__(cls, **context) -> None:
                 **context: Additional context for subclass initialization
             """
             super().__init_subclass__(**context)
+            NEWTYPE_LOGGER.debug(f"cls: {cls}")
             NEWTYPE_LOGGER.debug(base_type, base_type.__dict__)
-            NEWTYPE_LOGGER.debug("cls.__dict__: ", cls.__dict__)
+            NEWTYPE_LOGGER.debug(f"cls.__dict__: {cls.__dict__}")
 
             constructor = cls.__init__
             original_cls_dict = {}
@@ -201,19 +220,18 @@ def __init_subclass__(cls, **context) -> None:
             for k, v in base_type.__dict__.items():
                 if callable(v) and (k not in object.__dict__) and (k not in original_cls_dict):
                     NEWTYPE_LOGGER.debug(
-                        "callable(v) and (k not in object.__dict__) and \
-                            (k not in original_cls_dict) ; k: ",
-                        k,
+                        f"callable(v) and (k not in object.__dict__) and \
+                            (k not in original_cls_dict) ; k: {k}"
                     )
                     setattr(cls, k, NewTypeMethod(v, base_type))
                 elif k not in object.__dict__:
                     if k == "__dict__":
                         continue
                     setattr(cls, k, v)
                     NEWTYPE_LOGGER.debug("Set")
-            NEWTYPE_LOGGER.debug("original_cls_dict: ", original_cls_dict)
+            NEWTYPE_LOGGER.debug(f"original_cls_dict: {original_cls_dict}")
             for k, v in original_cls_dict.items():
-                NEWTYPE_LOGGER.debug("k in original_cls_dict: ", k)
+                NEWTYPE_LOGGER.debug(f"k in original_cls_dict: {k}")
                 if (
                     callable(v)
                     and k != "__init__"
@@ -228,10 +246,23 @@ def __init_subclass__(cls, **context) -> None:
                     NEWTYPE_LOGGER.debug("Set")
             NEWTYPE_LOGGER.debug("Setting cls.__init__")
             cls.__init__ = NewTypeInit(constructor)  # type: ignore[method-assign]
-            if hasattr(cls, "__slots__"):
-                NEWTYPE_LOGGER.debug("cls.__slots__: ", cls.__slots__)
             NEWTYPE_LOGGER.debug("Setting cls.__init__ completed")
-            NEWTYPE_LOGGER.debug("cls.__dict__: ", cls.__dict__, " at end of __init_subclass__")
+            # if hasattr(cls, "__slots__"):
+            #     NEWTYPE_LOGGER.debug(f"cls.__slots__: {cls.__slots__}")
+            #     BaseNewType.__slots__ = (
+            #         *(base_type.__slots__ if hasattr(base_type, "__slots__") else ()),
+            #         *cls.__slots__,
+            #         NEWTYPE_INIT_ARGS_STR,
+            #         NEWTYPE_INIT_KWARGS_STR,
+            #     )
+            #     NEWTYPE_LOGGER.debug(
+            #         f"cls.__slots__: {cls.__slots__}, at end of `__init_subclass__`"
+            #     )
+            # NEWTYPE_LOGGER.debug(f"cls.__dict__: {cls.__dict__}, at end of `__init_subclass__`")
+            if hasattr(BaseNewType, "__slots__"):
+                NEWTYPE_LOGGER.debug(
+                    f"BaseNewType.__slots__: {BaseNewType.__slots__}, at end of `__init_subclass__`"
+                )
 
         def __new__(cls, value=None, *_args, **_kwargs):
             """Create a new instance of BaseNewType.
@@ -244,7 +275,6 @@ def __new__(cls, value=None, *_args, **_kwargs):
                 *_args: Additional positional arguments
                 **_kwargs: Additional keyword arguments
             """
-            NEWTYPE_LOGGER.debug("cls, cls.__new__: ", cls, cls.__new__)
             if base_type.__new__ == object.__new__:
                 NEWTYPE_LOGGER.debug(
                     "base_type.__new__ == object.__new__; base_type.__new__ = ", base_type.__new__
@@ -272,9 +302,9 @@ def __new__(cls, value=None, *_args, **_kwargs):
                         if v is not UNDEFINED:
                             setattr(inst, k, v)
             else:
-                NEWTYPE_LOGGER.debug(
-                    "base_type.__new__ != object.__new__; base_type.__new__ = ", base_type.__new__
-                )
+                # NEWTYPE_LOGGER.debug(
+                #     "base_type.__new__ != object.__new__; base_type.__new__ = ", base_type.__new__
+                # )
                 inst = cast("BaseNewType", base_type.__new__(cls, value))
             return inst