Unique sentinel value for cache.get()

rhettinger · rhettinger · commit d37fb559102d · 2012-03-16T17:04:11.000-07:00
diff --git a/Lib/functools.py b/Lib/functools.py
@@ -175,8 +175,8 @@ def wrapper(*args, **kwds):
                 # simple caching without ordering or size limit
                 nonlocal hits, misses
                 key = make_key(args, kwds, typed) if kwds or typed else args
-                result = cache_get(key)
-                if result is not None:
+                result = cache_get(key, root)   # root used here as a unique not-found sentinel        
+                if result is not root:
                     hits += 1
                     return result
                 result = user_function(*args, **kwds)
