一個Python程序員的進化

不久前，在互聯網上出現了一篇有趣的文章，講的是對於同一個問題，不同層次的Python程序員編出的Python代碼顯示出了不同的風格，代碼都很簡單，有趣。下面讓我們一起來看看一個Python程序員是進階的全過程。

AD：

 

不久前，在互聯網上出現了一篇有趣的文章，講的是對於同一個問題，不同層次的Python程序員編出的Python代碼顯示出了不同的風格，代碼都很簡單，有趣。

編程新手

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

一年編程經驗(學Pascal的)

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

一年編程經驗(學C的)

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

一年編程經驗(讀過 SICP)

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

一年編程經驗(Python)

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

懶惰的Python程序員

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

更懶的Python程序員

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

Python 專家

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

Python 黑客

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')

專家級程序員

from c_math import fact
print fact(6)

大英帝國程序員

from c_maths import fact
print fact(6)

Web 設計人員

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)

Unix 程序員

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

Windows 程序員

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)

企業級程序員

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))

自己還是初學者 一年編程經驗(讀過 SICP)  用的是尾遞歸

Python 專家

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

用的是reduce.


學習到： xrange([start], stop[, step])

This function is very similar to range(), but returns an “xrange object” instead of a list. This is an opaque sequence type which yields the same values as the corresponding list, without actually storing them all simultaneously. The advantage of xrange() over range() is minimal (since xrange() still has to create the values when asked for them) except when a very large range is used on a memory-starved machine or when all of the range’s elements are never used (such as when the loop is usually terminated with break).

 

 

贊