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Issue 13227: Option to make the lru_cache() type specific (suggested by Andrew Koenig).

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This commit is contained in:
Raymond Hettinger 2011-10-20 08:57:45 -07:00
parent e3455c026a
commit cd9fdfd652
5 changed files with 49 additions and 12 deletions
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22
Lib/functools.py
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@ -121,12 +121,16 @@ except ImportError:
_CacheInfo = namedtuple("CacheInfo", "hits misses maxsize currsize")
def lru_cache(maxsize=100):
def lru_cache(maxsize=100, typed=False):
"""Least-recently-used cache decorator.
If *maxsize* is set to None, the LRU features are disabled and the cache
can grow without bound.
If *typed* is True, arguments of different types will be cached separately.
For example, f(3.0) and f(3) will be treated as distinct calls with
distinct results.
Arguments to the cached function must be hashable.
View the cache statistics named tuple (hits, misses, maxsize, currsize) with
@ -142,7 +146,7 @@ def lru_cache(maxsize=100):
# to allow the implementation to change (including a possible C version).
def decorating_function(user_function,
tuple=tuple, sorted=sorted, len=len, KeyError=KeyError):
*, tuple=tuple, sorted=sorted, map=map, len=len, type=type, KeyError=KeyError):
hits = misses = 0
kwd_mark = (object(),) # separates positional and keyword args
@ -156,7 +160,12 @@ def lru_cache(maxsize=100):
nonlocal hits, misses
key = args
if kwds:
key += kwd_mark + tuple(sorted(kwds.items()))
sorted_items = tuple(sorted(kwds.items()))
key += kwd_mark + sorted_items
if typed:
key += tuple(map(type, args))
if kwds:
key += tuple(type(v) for k, v in sorted_items)
try:
result = cache[key]
hits += 1
@ -177,7 +186,12 @@ def lru_cache(maxsize=100):
nonlocal hits, misses
key = args
if kwds:
key += kwd_mark + tuple(sorted(kwds.items()))
sorted_items = tuple(sorted(kwds.items()))
key += kwd_mark + sorted_items
if typed:
key += tuple(map(type, args))
if kwds:
key += tuple(type(v) for k, v in sorted_items)
with lock:
try:
result = cache[key]