add StrEqHashableMixin

CHANGELOG.md

@@ -3,3 +3,4 @@
 * added for_argument, attach_arguments and auto_adapt_to_methods to __all__ in `satella.coding`
 * added time_us to __all__ in `satella.time`
 * refactored `satella.cassandra.parallel_for`
+* added `StrEqHashableMixin`

docs/coding/structures.rst

@@ -58,6 +58,16 @@ If you need quick __hash__ and __eq__ operators from listed fields of the class.
 .. autoclass:: satella.coding.structures.OmniHashableMixin
     :members:
 
+StrEqHashableMixin
+==================
+
+A class that outfits your class with __eq__ and __hash__ based off the str() value of the
+class. So you got to define __str__ at the very least!
+
+.. autoclass:: satella.coding.structures.StrEqHashableMixin
+    :members:
+
+
 ReprableMixin
 =============
 

satella/__init__.py

-__version__ = '2.8.15_a6'
+__version__ = '2.8.15_a7'

satella/coding/structures/__init__.py

@@ -4,7 +4,7 @@ from .dictionaries import DictObject, apply_dict_object, DictionaryView, TwoWayD
 from .hashable_objects import HashableWrapper
 from .heaps import Heap, SetHeap, TimeBasedHeap, TimeBasedSetHeap
 from .immutable import Immutable, frozendict
-from .mixins import OmniHashableMixin, ReprableMixin
+from .mixins import OmniHashableMixin, ReprableMixin, StrEqHashableMixin
 from .proxy import Proxy
 from .ranking import Ranking
 from .singleton import Singleton, SingletonWithRegardsTo
@@ -16,6 +16,7 @@ __all__ = [
     'KeyAwareDefaultDict',
     'Proxy',
     'ReprableMixin',
+    'StrEqHashableMixin',
     'DirtyDict',
     'SortedList',
     'SelfCleaningDefaultDict',

satella/coding/structures/mixins.py

@@ -4,6 +4,18 @@ import typing as tp
 from abc import ABCMeta, abstractmethod
 
 
+class StrEqHashableMixin:
+    """
+    A mix-in that outfits your class with an __eq__ and __hash__ operator that take
+    their values from __str__ representation of your class.
+    """
+    def __eq__(self, other):
+        return str(self) == str(other)
+
+    def __hash__(self) -> int:
+        return hash(str(self))
+
+
 class OmniHashableMixin(metaclass=ABCMeta):
     """
     A mix-in. Provides hashing and equal comparison for your own class using specified fields.

tests/test_coding/test_structures.py

@@ -11,11 +11,23 @@ from satella.coding.structures import TimeBasedHeap, Heap, typednamedtuple, \
     OmniHashableMixin, DictObject, apply_dict_object, Immutable, frozendict, SetHeap, \
     DictionaryView, HashableWrapper, TwoWayDictionary, Ranking, SortedList, SliceableDeque, \
     DirtyDict, KeyAwareDefaultDict, Proxy, ReprableMixin, TimeBasedSetHeap, ExpiringEntryDict, SelfCleaningDefaultDict, \
-    CacheDict
+    CacheDict, StrEqHashableMixin
 
 
 class TestMisc(unittest.TestCase):
 
+    def test_str_eq_hashable_mixin(self):
+        class MyClass(StrEqHashableMixin):
+            def __init__(self, v: str):
+                self.v = v
+
+            def __str__(self) -> str:
+                return self.v
+
+        a = MyClass('a')
+        self.assertEqual(hash('a'), hash(a))
+        self.assertEqual(a, 'a')
+
     def test_proxy(self):
         a = Proxy(2)
         self.assertEqual(int(a), 2)