Class Memoize

source code

'Memoizes' a function, caching its return values for each input. If `expires` is specified, values are recalculated after `expires` seconds. If `background` is specified, values are recalculated in a separate thread.

>>> calls = 0
>>> def howmanytimeshaveibeencalled():
...     global calls
...     calls += 1
...     return calls
>>> fastcalls = memoize(howmanytimeshaveibeencalled)
>>> howmanytimeshaveibeencalled()
1
>>> howmanytimeshaveibeencalled()
2
>>> fastcalls()
3
>>> fastcalls()
3
>>> import time
>>> fastcalls = memoize(howmanytimeshaveibeencalled, .1, background=False)
>>> fastcalls()
4
>>> fastcalls()
4
>>> time.sleep(.2)
>>> fastcalls()
5
>>> def slowfunc():
...     time.sleep(.1)
...     return howmanytimeshaveibeencalled()
>>> fastcalls = memoize(slowfunc, .2, background=True)
>>> fastcalls()
6
>>> timelimit(.05)(fastcalls)()
6
>>> time.sleep(.2)
>>> timelimit(.05)(fastcalls)()
6
>>> timelimit(.05)(fastcalls)()
6
>>> time.sleep(.2)
>>> timelimit(.05)(fastcalls)()
7
>>> fastcalls = memoize(slowfunc, None, background=True)
>>> threading.Thread(target=fastcalls).start()
>>> time.sleep(.01)
>>> fastcalls()
9