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建议8:利用assert语句来发现问题建议9:数据交换值时不推荐使用中间交换变量建议10:充分利用lazy evaluation的特性建议11:理解枚举替代实现的缺陷建议12:不推荐使用type来进行类型检查建议13:尽量转换为浮点类型再做除法建议14:警惕eval()的安全漏洞建议15:使用enumerate()获取序列迭代的索引和值建议16:分清==与is的适用场景建议17:考虑兼容性,尽可能使用unicod建议18:构建合理的包层次来管理module
1 >>> from timeit import timer 2 >>> timer('temp=x;x=y;y=temp','x=2;y=3').timeit() 3 0.03472399711608887 4 >>> timer('x,y=y,x','x=2;y=3').timeit() 5 0.031581878662109375
1 >>> from collections import namedtuple 2 >>> seasons=namedtuple('seasons','spring summer autumn winter')._make(xrange(4)) 3 >>> print seasons 4 seasons(spring=0, summer=1, autumn=2, winter=3) 5 >>> print seasons.autumn 6 2
1 >>> seasons._replace(spring=2) # 不合理 2 seasons(spring=2, summer=1, autumn=2, winter=3) 3 >>> seasons.summer+seasons.autumn == seasons.winter # 无意义 4 true
1 from flufl.enum import enum 2 3 4 class seasons(enum): 5 spring = "spring" 6 summer = 2 7 autumn = 3 8 winter = 4 9 10 seasons = enum('seasons', 'spring summer autumn winter') 11 print seasons 12 print seasons.summer.value
1 >>> i=1 2 >>> while i!=1.5: 3 ... i=i+0.1 4 ... print i
1 # -*-coding:utf-8 -*- 2 3 import sys 4 from math import * 5 6 7 def expcalcbot(string): 8 try: 9 print 'your answer is', eval(string) 10 except nameerror: 11 print "the expression you enter is not valid." 12 13 14 while true: 15 print 'please enter a number or operation. enter e to complete. ' 16 17 inputstr = raw_input() 18 if inputstr == 'e': 19 sys.exit() 20 elif repr(inputstr) != ' ': 21 expcalcbot(inputstr)
输入:__import__("os").system("dir") 显示当前目录下的所有文件.
1 >>> person={'name': 'josn', 'age': 19, 'hobby': 'football'} 2 >>> for k,v in person.iteritems(): 3 ... print k, ":", v
1 >>> a="hi" 2 >>> b="hi" 3 >>> a is b 4 true 5 >>> a==b 6 true 7 >>> a1 ="i am using long string for testing" # 注意区分 8 >>> b1 ="i am using long string for testing" 9 >>> a1 is b1 10 false 11 >>> a1==b1 12 true
1 import codecs 2 3 4 content = open('manage.py', 'r').read() 5 6 if content[:3] == codecs.bom_utf8: 7 content = content[:3] 8 9 print content.decode("utf-8")
1 # coding=<encoding name> #方式一 2 #!/usr/bin/env python 3 4 # -*- coding:<encoding name> -*- #方式二 5 6 #!/usr/bin/env python 7 # vim:set fileencoding=<encoding name> #方式三
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