[SciPy-User] caching function values

nicky van foreest vanforeest@gmail....
Sat Mar 13 15:06:10 CST 2010


When calling a function for the first time I like to cache some
complicated computations (that only have to be done once), and then
use this cached stuff in all subsequent calls to the functions. I came
across the following trick on the net:

def dummy(x, firstTime = [1]):
    if firstTime[0] == 1:
        A = 3  # typically some lengthy do-once computation to obtain a matrix A
        dummy.A = A # store it
        firstTime[0] = 0 # ensure this piece of code will not be run again
    u = dummy.A*x  # use the cached value of A in the real computations
    return u

Are there other (less tricky) ways to achieve the same effect, without
using a class? (As far as I can see, using classes would involve some
extra lines of code, for instance, I have to instantiate it.)

Thanks for any advice.


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