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"""Decorator for caching computed values."""
from functools import wraps
# Instead of wrapper.__doc__ = f.__doc__ and wrapper.__name__ = f.__name__,
# use functools.wraps.
def memoize(limit=None, keymaker=None, cache_type=dict, debug=False):
"""Memoize decorator with an LRU cache.
When full, the cache discards the least recently used value.
You can pass cache_type=WeakValueDictionary (not tested).
"""
if not keymaker:
try:
from cPickle import dumps
except ImportError:
from pickle import dumps
keymaker = lambda *a, **kw: dumps((a, kw))
def decoratr(fn):
cache = cache_type()
popular = []
@wraps(fn)
def wrapper(*a, **kw):
key = keymaker(*a, **kw)
try:
popular.append(popular.pop(popular.index(key)))
except ValueError:
cache[key] = fn(*a, **kw)
popular.append(key)
if limit is not None and len(popular) > limit:
del cache[popular.pop(0)]
else:
if debug:
print('Hit cache of {0}(). Value:\n {1}'.format(
fn.__name__, key))
return cache[key]
wrapper.cache = cache
wrapper.popular = popular
wrapper.limit = limit
wrapper.func = fn
return wrapper
return decoratr
if __name__ == "__main__":
# Example usage
# Will cache up to 100 items, dropping the least recently used if
# the limit is exceeded.
@memoize(100)
def fibo(n):
if n > 1:
return fibo(n - 1) + fibo(n - 2)
else:
return n
print(fibo(100))
# Same as above, but with no limit on cache size
@memoize()
def fibonl(n):
if n > 1:
return fibo(n - 1) + fibo(n - 2)
else:
return n
print(fibonl(100))