Python的__builtin__模块中的一些要点知识

isinstance(obj,basestring)===isinstance(obj,(str,unicode))

writte=getattr(obj,'write',sys.stdout.write)

> Point=type('Point',(object,),{'x':0,'y':0})
> p=Point()
> p.x,p.y
(0, 0)
> p=Point(3,8)
Traceback (most recent call last):
 File "<pyshell#55>", line 1, in <module>
 p=Point(3,8)
TypeError: object() takes no parameters
> pprint.pprint(dir(Point))
['__class__',
 '__delattr__',
 '__dict__',
 '__doc__',
 '__format__',
 '__getattribute__',
 '__hash__',
 '__init__',
 '__module__',
 '__new__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__setattr__',
 '__sizeof__',
 '__str__',
 '__subclasshook__',
 '__weakref__',
 'x',
 'y']
> p.name='source point'
> p.name
'source point'
> pprint.pprint(dir(p))
['__class__',
 '__delattr__',
 '__dict__',
 '__doc__',
 '__format__',
 '__getattribute__',
 '__hash__',
 '__init__',
 '__module__',
 '__new__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__setattr__',
 '__sizeof__',
 '__str__',
 '__subclasshook__',
 '__weakref__',
 'name',
 'x',
 'y']
> def tostr(self):
 return '(%s,%s)'%(self.x,self.y)
> Point.__str__=tostr
> print p
(0,0)
> def init(self,x,y):
 self.x,self.y=x,y
  
> Point.__init__=init
> p2=Point(6,8)
> print p2
(6,8)
>

> def getrand():
 import random
 return random.randint(1,100)
> for i in iter(getrand,50):print i,#获取第一次得到50之前的所有1-100的随机数
32 19 82 28 30 41 100 39 71 29 45 30 94 77 62 26 25 19 82 20 55 20 43 73
> for i in iter(getrand,50):print i,#获取第一次得到50之前的所有1-100的随机数
22 54 14 25 60 65 16 80 61 5 48 61 2 30 90 98 70 10 55 45 23 72 87 39 70 3 84 85
>

> for i,name in enumerate(['C','C++','CSharp','Java','Python'],1):
 print '%d.%s'%(i,name)
1.C
2.C++
3.CSharp
4.Java
5.Python
>