python学习笔记三（类自定义属性 方法）
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#encoding=UTF-8'''Created on 2011-5-26@author: Administrator'''#静态变量class A: count=0 def __init__(self): self.__class__.count+=1 #把它当全局变量来用print A.counta=A()print a.countb=A()print b.count# __str__ 和 __repr__ 和 __del__ 和 __eval__class B: def __repr__(self): return "A()" def __str__(self): return "OK,I am in the class" x=B()print aprint x #结果被__str__重写了print repr(x) #repr函数用来取得对象的规范字符串表示。重写__repr__print eval("A()") '''012<__main__.A instance at 0x01AEE828>OK,I am in the classA()<__main__.A instance at 0x01AEEB20>''' # __cmp__的用法class C: def __cmp__(self,other): if other>=0:return -1 elif other<0: return 1 else: return 0 c = C()print c>-2 #trueprint c>2 #false # __nozero__ 用法 class Dog: alive = 0 def __nonzero__(self): if self.alive==0:return 0 else: return 1;def isDogAlive(d): if d:print "Alive" else :print"Dead" d = Dog()print d.alive #0isDogAlive(d) #Dead d.alive = 3isDogAlive(d) #Alive###########################__len__class D: def __len__(self): return 100d = D()print len(d) #100