Add callback function register on construct

cachetools/base.py

@@ -4,10 +4,11 @@
 class Cache(collections.MutableMapping):
     """Mutable mapping to serve as a simple cache or cache base class."""
 
-    def __init__(self, maxsize, missing=None, getsizeof=None):
+    def __init__(self, maxsize, missing=None, getsizeof=None, callback=None):
         self.__data = dict()
         self.__currsize = 0
         self.__maxsize = maxsize
+        self.callback = callback
         if missing:
             self.__missing = missing
         if getsizeof:
@@ -35,7 +36,9 @@ def __setitem__(self, key, value):
             raise ValueError('value too large')
         if key not in data or data[key][1] < size:
             while self.__currsize + size > maxsize:
-                self.popitem()
+                pkey, pvalue = self.popitem()
+                if self.callback is not None:
+                    self.callback(pkey, pvalue)
         if key in data:
             diffsize = size - data[key][1]
         else:

cachetools/lfu.py

@@ -7,8 +7,8 @@
 class LFUCache(Cache):
     """Least Frequently Used (LFU) cache implementation."""
 
-    def __init__(self, maxsize, missing=None, getsizeof=None):
-        Cache.__init__(self, maxsize, missing, getsizeof)
+    def __init__(self, maxsize, missing=None, getsizeof=None, callback=None):
+        Cache.__init__(self, maxsize, missing, getsizeof, callback)
         self.__counter = collections.Counter()
 
     def __getitem__(self, key, cache_getitem=Cache.__getitem__):

cachetools/lru.py

@@ -15,8 +15,8 @@ def unlink(self):
 class LRUCache(Cache):
     """Least Recently Used (LRU) cache implementation."""
 
-    def __init__(self, maxsize, missing=None, getsizeof=None):
-        Cache.__init__(self, maxsize, missing, getsizeof)
+    def __init__(self, maxsize, missing=None, getsizeof=None, callback=None):
+        Cache.__init__(self, maxsize, missing, getsizeof, callback)
         root = self.__root = _Link()
         root.prev = root.next = root
 

cachetools/rr.py

@@ -7,8 +7,8 @@ class RRCache(Cache):
     """Random Replacement (RR) cache implementation."""
 
     def __init__(self, maxsize, choice=random.choice, missing=None,
-                 getsizeof=None):
-        Cache.__init__(self, maxsize, missing, getsizeof)
+                 getsizeof=None, callback=None):
+        Cache.__init__(self, maxsize, missing, getsizeof, callback)
         self.__choice = choice
 
     def popitem(self):

cachetools/ttl.py

@@ -59,8 +59,8 @@ class TTLCache(Cache):
     """LRU Cache implementation with per-item time-to-live (TTL) value."""
 
     def __init__(self, maxsize, ttl, timer=time.time, missing=None,
-                 getsizeof=None):
-        Cache.__init__(self, maxsize, missing, getsizeof)
+                 getsizeof=None, callback=None):
+        Cache.__init__(self, maxsize, missing, getsizeof, callback)
         root = self.__root = _Link()
         root.ttl_prev = root.ttl_next = root
         root.lru_prev = root.lru_next = root