生成器代替迭代器

import re
import reprlib

RE_WORD = re.compile('\w+')

'''
生成器是迭代器
'''


def gen_123():
    print('start')
    yield 'A'
    print('continue')
    yield 'B'
    print('end')


for i in gen_123():
    print('-->', i)

'''
第一个循环：
start
--> A
第二个循环
continue
--> B
第三个循环：
end
for循环会捕获stopiteration的异常
'''


class Sentence:
    def __init__(self, text):
        self.text = text
        self.words = RE_WORD.findall(text)

    def __repr__(self):
        return 'Setence(%s)' % reprlib.repr(self.text)

    def __iter__(self):
        for word in self.words:
            yield word  # 含有yield关键字，就是一个生成器函数
        return


'''
使用生成器代替去实现一个迭代器
'''


# s4 = Sentence('pig and pepper')
# it = iter(s4)
# print(it)  # <generator object Sentence.__iter__ at 0x000001C8EA074AF0>
# print(next(it))
# print(next(it))
# print(next(it))


# 使用re。finditer返回生成器
class Sentence2:
    def __init__(self, text):
        self.text = text

    def __repr__(self):
        return 'Setence(%s)' % reprlib.repr(self.text)

    def __iter__(self):
        for match in RE_WORD.finditer(self.text):
            yield match.group()  # 含有yield关键字，就是一个生成器函数
        return


s4 = Sentence2('pig and pepper')
it = iter(s4)
# <generator object Sentence.__iter__ at 0x000001C8EA074AF0>
print(next(it))
print(next(it))
print(next(it))

1

 

def gen_123():
    print('start')
    yield 'A'
    print('continue')
    yield 'B'
    print('end')


res1 = [x * 3 for x in gen_123()]
'''
输出：
start
continue
end
'''

res2 = (x * 3 for x in gen_123())
# print(res2)
# print(next(res2))
# print(next(res2))
# print(next(res2))