Fix #40: Allow pickling of simple cache instances.

cachetools/ttl.py

@@ -49,9 +49,14 @@ def __call__(self):
             return self.__time
 
     def __getattr__(self, name):
-        # FIXME: for unittests timer.tick()
         return getattr(self.__timer, name)
 
+    def __getstate__(self):
+        return (self.__timer, self.__nesting)
+
+    def __setstate__(self, state):
+        self.__timer, self.__nesting = state
+
 
 class TTLCache(Cache):
     """LRU Cache implementation with per-item time-to-live (TTL) value."""

tests/__init__.py

@@ -202,6 +202,20 @@ def test_cache_getsizeof(self):
         self.assertEqual(3, cache.currsize)
         self.assertEqual(3, cache[3])
 
+    def test_cache_pickle(self):
+        import pickle
+        import sys
+
+        cache = self.cache(maxsize=2)
+        cache.update({1: 1, 2: 2})
+        if sys.version_info < (3, 0):
+            cache = pickle.loads(pickle.dumps(cache, -1))
+        else:
+            cache = pickle.loads(pickle.dumps(cache))
+        self.assertEqual(2, len(cache))
+        self.assertEqual(1, cache[1])
+        self.assertEqual(2, cache[2])
+
 
 class DecoratorTestMixin(object):
 

tests/test_rr.py

@@ -1,4 +1,5 @@
 import random
+import sys
 import unittest
 
 from cachetools import RRCache, rr_cache
@@ -40,3 +41,8 @@ def test_choice(self):
         self.assertEqual(3, cache[3])
         self.assertEqual(4, cache[4])
         self.assertNotIn(0, cache)
+
+    # random.choice cannot be pickled...
+    @unittest.skipIf(sys.version_info < (3, 0), 'not supported for Python < 3')
+    def test_cache_pickle(self):
+        CacheTestMixin.test_cache_pickle(self)