orbingol · April 27, 2022 21:50 · Jun 28, 2020 · Jun 28, 2020 · Jan 8, 2020 · Sep 18, 2019
diff --git a/copy_deepcopy.py b/copy_deepcopy.py
@@ -27,8 +27,9 @@ def __deepcopy__(self, memo):
         # Don't copy self reference
         memo[id(self)] = result
 
-        # Don't copy the cache
-        memo[id(self._cache)] = self._cache.__new__(dict)
+        # Don't copy the cache - if it exists
+        if hasattr(self, "_cache"):
+            memo[id(self._cache)] = self._cache.__new__(dict)
 
         # Deep copy all other attributes
         for k, v in self.__dict__.items():

diff --git a/copy_deepcopy.py b/copy_deepcopy.py
@@ -1,4 +1,5 @@
 import copy
+from itertools import chain
 
 
 class CopyTestClass(object):
@@ -50,8 +51,11 @@ def __copy__(self):
         cls = self.__class__
         result = cls.__new__(cls)
 
+        # Get all __slots__ of the derived class
+        slots = chain.from_iterable(getattr(s, '__slots__', []) for s in self.__class__.__mro__)
+
         # Copy all attributes
-        for var in self.__slots__:
+        for var in slots:
             setattr(result, var, copy.copy(getattr(self, var)))
 
         # Return updated instance
@@ -65,11 +69,15 @@ def __deepcopy__(self, memo):
         # Don't copy self reference
         memo[id(self)] = result
 
-        # Don't copy the cache
-        memo[id(self._cache)] = self._cache.__new__(dict)
+        # Don't copy the cache - if it exists
+        if hasattr(self, "_cache"):
+            memo[id(self._cache)] = self._cache.__new__(dict)
 
+        # Get all __slots__ of the derived class
+        slots = chain.from_iterable(getattr(s, '__slots__', []) for s in self.__class__.__mro__)
+
         # Deep copy all other attributes
-        for var in self.__slots__:
+        for var in slots:
             setattr(result, var, copy.deepcopy(getattr(self, var), memo))
 
         # Return updated instance

diff --git a/copy_deepcopy.py b/copy_deepcopy.py
@@ -0,0 +1,92 @@
+import copy
+
+
+class CopyTestClass(object):
+    def __init__(self, q, w):
+        self._a = q
+        self._b = w
+        self._cache = {}
+
+    def __copy__(self):
+        # Create a new instance
+        cls = self.__class__
+        result = cls.__new__(cls)
+
+        # Copy all attributes
+        result.__dict__.update(self.__dict__)
+
+        # Return updated instance
+        return result
+
+    def __deepcopy__(self, memo):
+        # Create a new instance
+        cls = self.__class__
+        result = cls.__new__(cls)
+
+        # Don't copy self reference
+        memo[id(self)] = result
+
+        # Don't copy the cache
+        memo[id(self._cache)] = self._cache.__new__(dict)
+
+        # Deep copy all other attributes
+        for k, v in self.__dict__.items():
+            setattr(result, k, copy.deepcopy(v, memo))
+
+        # Return updated instance
+        return result
+
+
+class CopyTestClassWithSlots(object):
+    __slots__ = ('_a', '_b', '_cache')
+
+    def __init__(self, q, w):
+        self._a = q
+        self._b = w
+        self._cache = {}
+
+    def __copy__(self):
+        # Create a new instance
+        cls = self.__class__
+        result = cls.__new__(cls)
+
+        # Copy all attributes
+        for var in self.__slots__:
+            setattr(result, var, copy.copy(getattr(self, var)))
+
+        # Return updated instance
+        return result
+
+    def __deepcopy__(self, memo):
+        # Create a new instance
+        cls = self.__class__
+        result = cls.__new__(cls)
+
+        # Don't copy self reference
+        memo[id(self)] = result
+
+        # Don't copy the cache
+        memo[id(self._cache)] = self._cache.__new__(dict)
+
+        # Deep copy all other attributes
+        for var in self.__slots__:
+            setattr(result, var, copy.deepcopy(getattr(self, var), memo))
+
+        # Return updated instance
+        return result
+
+
+# Testing deep copy with __dict__
+test1 = CopyTestClass(q=10, w=[1.0 for _ in range(10)])
+test1._cache["coins"] = 120
+test1c = copy.deepcopy(test1)
+
+# Testing copy with __slots__
+test2 = CopyTestClass(q=25, w=None)
+test2c = copy.copy(test2)
+
+# Testing deep copy with __slots__
+test3 = CopyTestClass(q=[1.0 for _ in range(4)], w=None)
+test3._b = "a string"
+test3._cache['test_me'] = 1020
+test3c = copy.deepcopy(test3)