Issue #10516: adding list.clear() and list.copy() methods

3 files changed, 46 insertions, 0 deletions

diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index 11a2993..4317535 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -844,6 +844,8 @@ class UserList(MutableSequence):
     def insert(self, i, item): self.data.insert(i, item)
     def pop(self, i=-1): return self.data.pop(i)
     def remove(self, item): self.data.remove(item)
+    def clear(self): self.data.clear()
+    def copy(self): return self.data.copy()
     def count(self, item): return self.data.count(item)
     def index(self, item, *args): return self.data.index(item, *args)
     def reverse(self): self.data.reverse()
diff --git a/Lib/test/list_tests.py b/Lib/test/list_tests.py
index e3a7845..89ea40f 100644
--- a/Lib/test/list_tests.py
+++ b/Lib/test/list_tests.py
@@ -425,6 +425,48 @@ class CommonTest(seq_tests.CommonTest):
 
         self.assertRaises(TypeError, u.reverse, 42)
 
+    def test_clear(self):
+        u = self.type2test([2, 3, 4])
+        u.clear()
+        self.assertEqual(u, [])
+
+        u = self.type2test([])
+        u.clear()
+        self.assertEqual(u, [])
+
+        u = self.type2test([])
+        u.append(1)
+        u.clear()
+        u.append(2)
+        self.assertEqual(u, [2])
+
+        self.assertRaises(TypeError, u.clear, None)
+
+    def test_copy(self):
+        u = self.type2test([1, 2, 3])
+        v = u.copy()
+        self.assertEqual(v, [1, 2, 3])
+
+        u = self.type2test([])
+        v = u.copy()
+        self.assertEqual(v, [])
+
+        # test that it's indeed a copy and not a reference
+        u = self.type2test(['a', 'b'])
+        v = u.copy()
+        v.append('i')
+        self.assertEqual(u, ['a', 'b'])
+        self.assertEqual(v, u + ['i'])
+
+        # test that it's a shallow, not a deep copy
+        u = self.type2test([1, 2, [3, 4], 5])
+        v = u.copy()
+        v[2].append(666)
+        self.assertEqual(u, [1, 2, [3, 4, 666], 5])
+        self.assertEqual(u, v)
+
+        self.assertRaises(TypeError, u.copy, None)
+
     def test_sort(self):
         u = self.type2test([1, 0])
         u.sort()
diff --git a/Lib/test/test_descrtut.py b/Lib/test/test_descrtut.py
index 2db3d33..c3355b9 100644
--- a/Lib/test/test_descrtut.py
+++ b/Lib/test/test_descrtut.py
@@ -199,6 +199,8 @@ You can get the information from the list type:
      '__str__',
      '__subclasshook__',
      'append',
+     'clear',
+     'copy',
      'count',
      'extend',
      'index',