Not long ago, an interesting article appeared on the internet, showing that for the same problem, programmers at different levels write Python code in different styles. The code is all very simple and interesting.

Novice programmer

def factorial(x):
    if x == 0:
        return 1
    else:
        return x * factorial(x - 1)
print factorial(6)

One year of programming experience (learned Pascal)

def factorial(x):
    result = 1
    i = 2
    while i <= x:
        result = result * i
        i = i + 1
    return result
print factorial(6)

One year of programming experience (learned C)

def fact(x): #{
    result = i = 1;
    while (i <= x): #{
        result *= i;
        i += 1;
    #}
    return result;
#}
print(fact(6))

One year of programming experience (read SICP)

@tailcall
def fact(x, acc=1):
    if (x > 1): return (fact((x - 1), (acc * x)))
    else: return acc
print(fact(6))

One year of programming experience (Python)

def Factorial(x):
    res = 1
    for i in xrange(2, x + 1):
        res *= i
    return res
print Factorial(6)

Lazy Python programmer

def fact(x):
    return x > 1 and x * fact(x - 1) or 1
print fact(6)

Lazier Python programmer

f = lambda x: x and x * f(x - 1) or 1
print f(6)

Python expert

import operator as op
import functional as f
fact = lambda x: f.foldl(op.mul, 1, xrange(2, x + 1))
print fact(6)

Python hacker

import sys
@tailcall
def fact(x, acc=1):
    if x: return fact(x.__sub__(1), acc.__mul__(x))
    return acc
sys.stdout.write(str(fact(6)) + '\n')

Expert-level programmer

import c_math
fact = c_math.fact
print fact(6)

British Empire programmer

import c_maths
fact = c_maths.fact
print fact(6)

Web designer

def factorial(x):
    #-------------------------------------------------
    #--- 这段代码是从 Math Vault 那弄过来滴---
    #--- 计算阶乘 （C）亚瑟·史密斯 1999年---
    #-------------------------------------------------
    result = str(1)
    i = 1 #谢谢亚当
    while i <= x:
        #result = result * i #It's faster to use *=
        #result = str(result * result + i)
           #result = int(result *= i) #??????
        result str(int(result) * i)
        #result = int(str(result) * i)
        i = i + 1
    return result
print factorial(6)

Unix programmer

import os
def fact(x):
    os.system('factorial ' + str(x))
fact(6)

Windows programmer

NULL = None
def CalculateAndPrintFactorialEx(dwNumber,
                                 hOutputDevice,
                                 lpLparam,
                                 lpWparam,
                                 lpsscSecurity,
                                 *dwReserved):
    if lpsscSecurity != NULL:
        return NULL #Not implemented
    dwResult = dwCounter = 1
    while dwCounter <= dwNumber:
        dwResult *= dwCounter
        dwCounter += 1
    hOutputDevice.write(str(dwResult))
    hOutputDevice.write('\n')
    return 1
import sys
CalculateAndPrintFactorialEx(6, sys.stdout, NULL, NULL, NULL,
 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL)

Enterprise programmer

def new(cls, *args, **kwargs):
    return cls(*args, **kwargs)
 
class Number(object):
    pass
 
class IntegralNumber(int, Number):
    def toInt(self):
        return new (int, self)
 
class InternalBase(object):
    def __init__(self, base):
        self.base = base.toInt()
 
    def getBase(self):
        return new (IntegralNumber, self.base)
 
class MathematicsSystem(object):
    def __init__(self, ibase):
        Abstract
 
    @classmethod
    def getInstance(cls, ibase):
        try:
            cls.__instance
        except AttributeError:
            cls.__instance = new (cls, ibase)
        return cls.__instance
 
class StandardMathematicsSystem(MathematicsSystem):
    def __init__(self, ibase):
        if ibase.getBase() != new (IntegralNumber, 2):
            raise NotImplementedError
        self.base = ibase.getBase()
 
    def calculateFactorial(self, target):
        result = new (IntegralNumber, 1)
        i = new (IntegralNumber, 2)
        while i <= target:
            result = result * i
            i = i + new (IntegralNumber, 1)
        return result
 
print StandardMathematicsSystem.getInstance(new (InternalBase,
new (IntegralNumber, 2))).calculateFactorial(new (IntegralNumber, 6))