Merge pull request #4 from box/lru_cache

Improved the LRUCache class and added dostrings

Author: Jeff-Meadows

boxsdk/object/events.py

@@ -130,7 +130,9 @@ def generate_events_with_long_polling(self, stream_position=None):
                     if message == 'new_change':
                         next_stream_position = stream_position
                         for event, next_stream_position in self._get_all_events_since(stream_position):
-                            if event_ids.get(event['event_id']) == -1:
+                            try:
+                                event_ids.get(event['event_id'])
+                            except KeyError:
                                 yield event
                                 event_ids.set(event['event_id'])
                         stream_position = next_stream_position

boxsdk/util/lru_cache.py

@@ -6,19 +6,47 @@
 
 class LRUCache(object):
     def __init__(self, capacity=512):
+        """
+        :param capacity:
+            The Maximum number of key-value pairs can be cached.
+        :type capacity:
+            `int`
+        """
         super(LRUCache, self).__init__()
         self.capacity = capacity
         self.cache = OrderedDict()
 
     def get(self, key):
-        try:
-            value = self.cache.pop(key)
-            self.cache[key] = value
-            return value
-        except KeyError:
-            return -1
+        """
+        Look up the value in cache using the associated key. Returns the value if found.
+        Raises :class:`KeyError` otherwise.
+
+        :param key:
+            The key used to look up the cache.
+        :type key:
+            `unicode`
+        :return:
+            The value associated with the key if exists.
+        :raises:
+            :class:`KeyError` if the key doesn't exist.
+        """
+        value = self.cache.pop(key)
+        self.cache[key] = value
+        return value
 
     def set(self, key, value=None):
+        """
+        Store the key-value pair to cache.
+
+        :param key:
+            The key associated with the value to be stored. It's used to look up the cache.
+        :type key:
+            `unicode`
+        :param value:
+            The value to be stored.
+        :type value:
+            varies
+        """
         try:
             self.cache.pop(key)
         except KeyError:

test/unit/util/test_lru_cache.py

@@ -18,7 +18,8 @@ def keys():
 def test_lru_cache_returns_minus_one_for_missing_key(lru_cache, keys):
     # pylint:disable=redefined-outer-name
     for key in keys:
-        assert lru_cache.get(key) is -1
+        with pytest.raises(KeyError):
+            lru_cache.get(key)
 
 
 def test_lru_cache_returns_none_for_existing_key(lru_cache, keys):
@@ -34,9 +35,11 @@ def test_lru_cache_ejects_least_recently_used_key(lru_cache, keys):
     for key in keys:
         lru_cache.set(key)
     lru_cache.set('another key')
-    assert lru_cache.get(keys[0]) is -1
+    with pytest.raises(KeyError):
+        lru_cache.get(keys[0])
     assert lru_cache.get('another key') is None
     for key in keys[1:]:
         assert lru_cache.get(key) is None
     lru_cache.set('yet another key')
-    assert lru_cache.get('another key') is -1
+    with pytest.raises(KeyError):
+        lru_cache.get('another key')