generator-生成器

# _*_coding:utf-8_*_
# 作者：王佃元
# 日期：2019/12/29

# 生成器两种创建方式：1、列表生成式中括号改为小括号
# def f(n):
#     return n**3
# a = [x for x in range(10)]
# a = [x*2 for x in range(10)]
# # 列表生成式
# a = [f(x) for x in range(10)]
# print(a, type(a))
# t = ('123', 8, 0)
# a, b, c = t    # 赋值
# print(a, b, c)
# a = (x*2 for x in range(5))
# print(next(a))  # == a.__netx__() in py2
# for i in a:     # 生成器就是一个可迭代对象，iterable
#     print(i, type(i))
# def foo():
#     print('OK')
#     yield 1
#     print('OK2')
#     yield 2
# g = foo()
# # next(g)
# # next(g)
# for i in g:
#     i
# 可迭代对象：对象拥有iter方法的就是可迭代对象

# def fib(max):
#     n, before, after = 0, 0, 1
#     while n < max:
#         # print(after)
#         yield before
#         before, after = after, before + after
#         n = n + 1
# g = fib(8)
# print(next(g))
# print(next(g))
# print(next(g))

def bar():
    print('OK1')
    count = yield 1
    print(count)
    print('OK2')
    yield 2
b = bar()
b.send(None)    # 第一次send前如果没有next，只能传一个‘None’参数。如果之前有next则可以直接传参数
ret = b.send('hello')
print(ret)