Python yield的简单应用和理解（代码）

Python yield的简单应用和理解（代码）

# coding=utf-8
from random import randint


def rand_gen(aList):
    while len(aList) > 0:
        yield aList.pop(randint(0, len(aList)-1))


def counter(start_at=0):
    count = start_at
    while True:
        # 第一次val等于yield的返回值,随后因为while的存在yield没有返回值,yield返回None
        # 随后count被加一, yield再次有值可以返回
        val = (yield count)
        if val is not None:
            count = val
        else:
            count += 1


for item in rand_gen(['rock', 'paper', 'scissors']):
    print item

count = counter(5)
print count.next()      # 5
print count.next()      # 6
print count.send(9)     # 9
print count.next()      # 10
print count.close()     # None