Python程序员的进化过程

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

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

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

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

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

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

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

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

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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')

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from c_math import fact
print fact(6)

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from c_maths import fact
print fact(6)

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def factorial(x):
#-------------------------------------------------
#--- Code snippet from The Math Vault          ---
#--- Calculate factorial (C) Arthur Smith 1999 ---
#-------------------------------------------------
result = str(1)
i = 1 #Thanks Adam
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)

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

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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)

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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))