Obfuscated factorial

[Gene Heskett]

On Saturday 26 October 2013 10:12:33 Steven D'Aprano did opine:

> 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
> 
Nice, but will it go to 70? :) 
> 
> It goes without saying that this isn't Pythonic :-)


Cheers, Gene
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