Obfuscated factorial

[Steven D'Aprano]

Just for fun:


class Numberator:
    def __init__(self, number):
        self.__number = number
    def evaluate(self):
        return self.__number

class Multiplier:
    def __init__(self, multiplier, multiplicand):
        self.multiplier = multiplier
        self.multiplicand = multiplicand
    def evaluate(self):
        return self.multiplier * self.multiplicand.evaluate()

class FactorialBuilder:
    def __init__(self, number):
        if not isinstance(number, int):
            raise TypeError
        if number < 0:
            raise ValueError
        self.__number = number
    def build(self):
        multiplicand = Numberator(1)
        for n in range(2, self.__number + 1):
            multiplicand = Multiplier(n, multiplicand)
        return Factorialiser(multiplicand)

class Factorialiser:
    def __init__(self, evaluatorix):
        self.__evaluatorix = evaluatorix
    def calculate(self):
        return self.__evaluatorix.evaluate()

for i in range(16):
    print(i, FactorialBuilder(i).build().calculate())



And the output is:

0 1
1 1
2 2
3 6
4 24
5 120
6 720
7 5040
8 40320
9 362880
10 3628800
11 39916800
12 479001600
13 6227020800
14 87178291200
15 1307674368000



It goes without saying that this isn't Pythonic :-)


-- 
Steven