Python: static variable decorator

Question

I\'d like to create a decorator like below, but I can\'t seem to think of an implementation that works. I\'m starting to think it\'s not possible, but thought I would ask yo

Answer 1

When you need to save state between invocations of a function, you are almost always better off using a generator/coroutine or an object. Since you want to use "bare" variable names, then you'll want the coroutine version.

# the coroutine holds the state and yields rather than returns values
def totalgen(x=0, y=0, z=0):
    while True:
       a, b, c = (yield x, y, z)
       x += a
       y += b
       z += c

# the function provides the expected interface to callers
def runningtotal(a, b, c, totalgen=totalgen()):
    try:
        return totalgen.send((a, b, c))    # conveniently gives TypeError 1st time
    except TypeError:
        totalgen.next()                    # initialize, discard results
        return totalgen.send((a, b, c))

The result is a function that accumulates totals of the three values passed to it, exactly as if it had static variables, but the accumulators are plain old local variables in what is essentially an infinite generator.