.gitignore

 # python
 __pycache__
 *.egg-info
+build
+dist
 
 # static checking
 .coverage

CHANGELOG

+# 0.1.0 - initial release
+## Major Updates
+* added equality mixin for standard equality checks
+* added repr mixin for better default reprs
+
+# 0.2.0 - frozen
+## Minor Updates
+* added a frozen mixin

din.py

@@ -287,3 +287,24 @@ class ReprMixin:
     def __repr__(self) -> str:
         # the repr ID dict is meant to track per repr call.
         return _ReprFormatter().format_obj(self, indent=self._repr_indent)
+
+
+class FrozenMixin:
+    """
+    A mixin to freeze an object.
+
+    Only freezes the object's attributes themselves, not any
+    mutability within those attributes.  For instance, you can't
+    say foo.my_string = 'new thing', but you can do foo.my_list.append('new thing').
+    """
+
+    def __setattr__(self, name: str, value: typing.Any) -> None:
+        # if the caller is self.__init__, make the update
+        stack = inspect.stack()
+        caller = stack[1].frame.f_locals.get('self', None)
+        func = stack[1].function
+        if caller is self and func == '__init__':
+            object.__setattr__(self, name, value)
+            return
+        # else, don't
+        raise AttributeError(f"Can't set {name}, because {type(self).__name__} is frozen.")

setup.py

@@ -106,6 +106,11 @@ setuptools.setup(
         'dev': [
             'bpython==0.17.1',
         ],
+        'dist': [
+            'setuptools',
+            'wheel',
+            'twine',
+        ],
     },
     # give your package an executable.
     entry_points={

test.py

@@ -578,3 +578,30 @@ def test_independent_reprs() -> None:
     # the reprs are as expected
     assert actual_repr == expected_repr
     assert other_actual_repr == other_expected_repr
+
+
+class _FrozenTestObject(din.FrozenMixin):
+    def __init__(self) -> None:
+        super().__init__()
+        self.my_string = 'original'
+
+
+def test_frozen() -> None:
+    # Given
+    # a frozen object
+    frozen = _FrozenTestObject()
+    # an expected error
+    expected_message = "Can't set my_string, because _FrozenTestObject is frozen."
+
+    # When
+    # an attribute is set
+    try:
+        frozen.my_string = 'changed!'
+    except AttributeError as error:
+        actual_message = str(error)
+
+    # Then
+    # an attribute error is raised
+    assert expected_message == actual_message
+    # the value didn't change
+    assert frozen.my_string == 'original'

version.py

@@ -2,7 +2,7 @@
 
 
 # [ API ]
-VERSION = '0.1.0'
+VERSION = '0.2.0'
 
 
 # [ Vulture ]