python_迭代器_生成器

1.迭代器實現類對象的循環遍歷

class ShoppingCart(object):
    def __init__(self):
        self.index = 0
        self.good = [1, 3, 5, 7, 9]

    def __iter__(self):
        return self

    def __next__(self):
        if self.index < len(self.good):
            data = self.good[self.index]
            self.index += 1
            return data
        else:
            raise StopIteration

    def next(self):
        return self.__next__()

if __name__=="__main__":
    cart = ShoppingCart()
    for good in cart:
        print(good)

2.生成器：生成器一定是迭代器，迭代器一定是可迭代的

class ShoppingCart(object):
    def __init__(self, count, price):
        self.count = count
        self.price = price

    def generat(self):
        for i in range(self.count):
            yield (i+1) * self.price

if __name__=="__main__":
    cart = ShoppingCart(5, 0.6)
    good = cart.generat()
    print(dir(good))
    for g in good:
        print(g)