bpo-27141: Fix collections.UserList and UserDict shallow copy. (GH-4094)

1 files changed, 14 insertions, 0 deletions

diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index 706907a..960d82a 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -1038,6 +1038,13 @@ class UserDict(_collections_abc.MutableMapping):
 
     # Now, add the methods in dicts but not in MutableMapping
     def __repr__(self): return repr(self.data)
+    def __copy__(self):
+        inst = self.__class__.__new__(self.__class__)
+        inst.__dict__.update(self.__dict__)
+        # Create a copy and avoid triggering descriptors
+        inst.__dict__["data"] = self.__dict__["data"].copy()
+        return inst
+
     def copy(self):
         if self.__class__ is UserDict:
             return UserDict(self.data.copy())
@@ -1050,6 +1057,7 @@ class UserDict(_collections_abc.MutableMapping):
             self.data = data
         c.update(self)
         return c
+
     @classmethod
     def fromkeys(cls, iterable, value=None):
         d = cls()
@@ -1118,6 +1126,12 @@ class UserList(_collections_abc.MutableSequence):
     def __imul__(self, n):
         self.data *= n
         return self
+    def __copy__(self):
+        inst = self.__class__.__new__(self.__class__)
+        inst.__dict__.update(self.__dict__)
+        # Create a copy and avoid triggering descriptors
+        inst.__dict__["data"] = self.__dict__["data"][:]
+        return inst
     def append(self, item): self.data.append(item)
     def insert(self, i, item): self.data.insert(i, item)
     def pop(self, i=-1): return self.data.pop(i)