day14_生成器进阶

1.send使用：

def generator():
    print("123")
    num = yield 1
    print("---"+num)
    print("456")
    yield 2
    print("987")
g = generator()
print(g.__next__())　　#next遇到yield停止，后send赋值于num
print(g.send("hello"))

结果：

123
1
---hello
456
2

send 获取下一个值的效果和next基本一致

只是在获取下一个值的时候，给上一yield的位置传递一个数据
使用send的注意事项
 　　第一次使用生成器的时候 是用next获取下一个值
　　最后一个yield不能接受外部的值

#计算移动平均值
    
def averager():
    total = 0.0
    count = 0
    average = None
    while True:
        term = yield average
        total += term
        count += 1
        average = total/count


g_avg = averager()
next(g_avg) #
print(g_avg.send(10))
print(g_avg.send(30))
print(g_avg.send(5))

   #              averager    total   count   term
   # next()       None        0       1       None
   # send(10)     10          10      2       10
   # send(30)     30          40      3       20
   # send(5)      5           45      4       5
---------------------------------------------------------

def init(func):  #在调用被装饰生成器函数的时候首先用next激活生成器
    def inner(*args,**kwargs):
        g = func(*args,**kwargs)
        next(g)
        return g
    return inner

@init
def averager():
    total = 0.0
    count = 0
    average = None
    while True:
        term = yield average
        total += term
        count += 1
        average = total/count


g_avg = averager()
# next(g_avg)   在装饰器中执行了next方法
print(g_avg.send(10))
print(g_avg.send(30))
print(g_avg.send(5))