python摘记

iterator支持两种builtin types：__iter__ 和 __next__，资料：https://docs.python.org/2/library/stdtypes.html#iterator.next

generator：https://wiki.python.org/moin/Generators

generator和iterator的区别：http://stackoverflow.com/questions/2776829/difference-between-pythons-generators-and-iterators

yield in python：http://www.ibm.com/developerworks/cn/opensource/os-cn-python-yield/index.html

例如

class Fab(object): 
    def __init__(self, max): 
        self.max = max 
        self.n, self.a, self.b = 0, 0, 1 

    def __iter__(self): 
        return self 

    def next(self): 
        if self.n < self.max: 
            r = self.b 
            self.a, self.b = self.b, self.a + self.b 
            self.n = self.n + 1 
            return r 
        raise StopIteration()