conditional computation

[robert]

Bruno Desthuilliers wrote:
> robert a écrit :
> (snip)
>> class MemoCache(dict): # cache expensive Objects during a session 
>> (memory only)
>>    def memo(self, k, f):
>>        try: return self[k]
>>        except KeyError:            #<--------- was error 
>>            return self.setdefault(k, f())
>> cache=MemoCache()
>> ...
>>
>> o = cache.memo( complex-key-expr, lambda: expensive-calc-expr )
>>
> 
> And how do you get back the cached value without rewriting both 
> complex-key-expr *and* expensive-calc-expr ? Or did I missed the point ?

the complex-key-expr is written only once in the code - execution inevitable.

expensive-calc-expr is  written only once in code and expensive execution (I have mostly matrix math) is only done at "f()" time.


-robert