一个Python程序员的进化

[url]http://developer.51cto.com/art/201102/244479.htm[/url]


[url]http://www.pythonclub.org/hacks/evolution[/url]


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。

[b]编程新手[/b]

def factorial(x):
[*] if x == 0:

return 1
[*] else:

return x * factorial(x - 1)
[*]print factorial(6)


[b]一年编程经验(学Pascal的)[/b]

def factorial(x):
[*] result = 1

i = 2
[*] while i = x:

result result = result * i
[*] i i = i + 1

return result
[*]print factorial(6)


[b]一年编程经验(学C的)[/b]

def fact(x): #{
[*] result = i = 1;

while (i = x): #{
[*] result *= i;

i += 1;
[*] #}

return result;
[*]#}

print(fact(6))

[b]一年编程经验(读过 SICP)[/b]

@tailcall
[*]def fact(x, acc = 1 ):

if (x > 1): return (fact((x - 1), (acc * x)))
[*] else: return acc

print(fact(6))

[b]一年编程经验(Python)[/b]

def Factorial(x):
[*] res = 1

for i in xrange(2, x + 1):
[*] res *= i

return res
[*]print Factorial(6)


[b]懒惰的Python程序员[/b]

def fact(x):
[*] return x > 1 and x * fact(x - 1) or 1

print fact(6)

[b]更懒的Python程序员[/b]

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


[b]Python 专家[/b]

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


[b]Python 黑客[/b]

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' )


[b]专家级程序员[/b]

from c_math import fact
[*]print fact( 6 )


[b]大英帝国程序员[/b]

from c_maths import fact
[*]print fact( 6 )


[b]Web 设计人员[/b]

def factorial(x):
[*] #-------------------------------------------------

#--- Code snippet from The Math Vault ---
[*] #--- Calculate factorial (C) Arthur Smith 1999 ---

#-------------------------------------------------
[*] result = str( 1 )

i = 1 #Thanks Adam
[*] while i

#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 )


[b]Unix 程序员[/b]

import os
[*]def fact(x):

os.system( 'factorial ' + str(x))
[*]fact( 6 )


[b]Windows 程序员[/b]

NULL = None
[*]def CalculateAndPrintFactorialEx(dwNumber,

hOutputDevice,
[*] lpLparam,

lpWparam,
[*] lpsscSecurity,

*dwReserved):
[*] if lpsscSecurity != NULL:

return NULL #Not implemented
[*] dwResult = dwCounter = 1

while dwCounter
[*] 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)

[b]企业级程序员
[/b]

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
[*] result = result * i

i = i + new (IntegralNumber, 1 )
[*] return result


[*]print StandardMathematicsSystem.getInstance(new (InternalBase,

new (IntegralNumber, 2 ))).calculateFactorial(new (IntegralNumber, 6 ))