一个 Python 程序员的进化

不久前，在互联网上出现了一篇有趣的文章，讲的是对于同一个问题，不同层次的Python程序员编出的Python代码显示出了不同的风格，代码都 很简单，有趣。

编程新手

1. def factorial(x):
2. if x == 0:
3. return 1
4. else:
5. return x * factorial(x – 1)
6. print factorial(6)

一年编程经验(学Pascal的)

1. def factorial(x):
2. result = 1
3. i = 2
4. while i <= x:
5. resultresult = result * i
6. ii = i + 1
7. return result
8. print factorial(6)

一年编程经验(学C的)

1. def fact(x): #{
2. result = i = 1;
3. while (i <= x): #{
4. result *= i;
5. i += 1;
6. #}
7. return result;
8. #}
9. print(fact(6))

一年编程经验(读过 SICP)

1. @tailcall
2. def fact(x, acc=1):
3. if (x > 1): return (fact((x – 1), (acc * x)))
4. else: return acc
5. print(fact(6))

一年编程经验(Python)

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

懒惰的Python程序员

1. def fact(x):
2. return x > 1 and x * fact(x – 1) or 1
3. print fact(6)

更懒的Python程序员

1. f = lambda x: x and x * f(x – 1) or 1
2. print f(6)

Python 专家

1. fact = lambda x: reduce(int.__mul__, xrange(2, x + 1), 1)
2. print fact(6)

Python 黑客

1. import sys
2. @tailcall
3. def fact(x, acc=1):
4. if x: return fact(x.__sub__(1), acc.__mul__(x))
5. return acc
6. sys.stdout.write(str(fact(6)) + ‘\n’)

专家级程序员

1. from c_math import fact
2. print fact(6)

大英帝国程序员

1. from c_maths import fact
2. print fact(6)

Web 设计人员

1. def factorial(x):
2. #————————————————-
3. #— Code snippet from The Math Vault —
4. #— Calculate factorial (C) Arthur Smith 1999 —
5. #————————————————-
6. result = str(1)
7. i = 1 #Thanks Adam
8. while i <= x:
9. #result = result * i #It’s faster to use *=
10. #result = str(result * result + i)
11. #result = int(result *= i) #??????
12. result = str(int(result) * i)
13. #result = int(str(result) * i)
14. i = i + 1
15. return result
16. print factorial(6)

Unix 程序员

1. import os
2. def fact(x):
3. os.system(‘factorial ‘ + str(x))
4. fact(6)

Windows 程序员

1. NULL = None
2. def CalculateAndPrintFactorialEx(dwNumber,
3. hOutputDevice,
4. lpLparam,
5. lpWparam,
6. lpsscSecurity,
7. *dwReserved):
8. if lpsscSecurity != NULL:
9. return NULL #Not implemented
10. dwResult = dwCounter = 1
11. while dwCounter <= dwNumber:
12. dwResult *= dwCounter
13. dwCounter += 1
14. hOutputDevice.write(str(dwResult))
15. hOutputDevice.write(‘\n’)
16. return 1
17. import sys
18. CalculateAndPrintFactorialEx(6, sys.stdout, NULL, NULL, NULL,
19. NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL)

企业级程序员

1. def new(cls, *args, **kwargs):
2. return cls(*args, **kwargs)
3. class Number(object):
4. pass
5. class IntegralNumber(int, Number):
6. def toInt(self):
7. return new (int, self)
8. class InternalBase(object):
9. def __init__(self, base):
10. self.base = base.toInt()
11. def getBase(self):
12. return new (IntegralNumber, self.base)
13. class MathematicsSystem(object):
14. def __init__(self, ibase):
15. Abstract
16. @classmethod
17. def getInstance(cls, ibase):
18. try:
19. cls.__instance
20. except AttributeError:
21. cls.__instance = new (cls, ibase)
22. return cls.__instance
23. class StandardMathematicsSystem(MathematicsSystem):
24. def __init__(self, ibase):
25. if ibase.getBase() != new (IntegralNumber, 2):
26. raise NotImplementedError
27. self.base = ibase.getBase()
28. def calculateFactorial(self, target):
29. result = new (IntegralNumber, 1)
30. i = new (IntegralNumber, 2)
31. while i <= target:
32. result = result * i
33. i = i + new (IntegralNumber, 1)
34. return result
35. print StandardMathematicsSystem.getInstance(new (InternalBase,
36. new (IntegralNumber, 2))).calculateFactorial(new (IntegralNumber, 6))