python 类的变量/方法 & 实例的变量/方法

类的变量/方法 & 实例的变量/方法

# -*- coding: gb18030 -*-
class Singleton(object):
    #变量在定义时候不区分“属于实例”还是“属于类”的
    #在调用时候区分
    # Singleton.__instance则是类的成员
    # self.var则是实例的成员
    __instance = None
    var = 3

    #类的方法
    def __new__(cls, *args, **kwd):
        if Singleton.__instance is None:
            print "singleton"
            #print "cls:", cls
            #print "args:", args
            #print "kwd:", kwd
            Singleton.__instance = object.__new__(cls, *args, **kwd)
            return Singleton.__instance

    #实例方法
    def doSth(self):
        print "do sth", self.var
    #类的方法
    def doSth2(self):
        print "do sth2", Singleton.var

class NonSingleton(object):
    __instance = None

    def __new__(cls, *args, **kwd):
        print "non singleton"
        NonSingleton.__instance = object.__new__(cls, *args, **kwd)
        return NonSingleton.__instance
    
class MyClass(Singleton):
    pass

class MyClass2(NonSingleton):
    pass

a=MyClass()
b=MyClass()

a.doSth()
a.doSth2()
a.var=4
Singleton.var=5
a.doSth()
a.doSth2()

c=MyClass2()
d=MyClass2()