《python Cook Book》chapter 6 notes.

一、缓存环的实现

该节中讲述了类切换技术和方法切换技术。当需要成组地切换所有的方法时，类切换方法可能是最佳的，而方法切换则在需要更细的行为粒度控制的时候更加合适。

class RingBuff(object):    def __init__(self, maxsize):        self.maxsize = maxsize        self.buff = []    class __Full(object):        def append(self, x):            self.buff[self.cur] = x            self.cur = (self.cur + 1) % self.maxsize        def tolist(self): # return with right order             return self.buff[self.cur:] + self.buff[:self.cur]    def append(self, data):        self.buff.append(data)        if (len(self.buff) == self.maxsize):            self.cur = 0            self.__class__ = self.__Full # change class    def tolist(self):        return self.buffif __name__ == '__main__':    buff = RingBuff(5)    for x in xrange(4): buff.append(x)    print buff.tolist()    buff.append(4)    buff.append(5)    print buff.tolist(

二、__init__参数自动初始化实例变量

def attributesFromDict(d):    self = d.pop('self')    for name, value in d.iteritems():        setattr(self, name, value)class Myclass(object):    def __init__(self, name, age, weight):        attributesFromDict(locals())if __name__ == '__main__':    student = Myclass('asdf', 23, 64)    print student.name, student.age, student.