yield解析

1.yield能够用来为一个函数返回值塞数据

代码：

def addlist(alist):
    for i in alist:
        yield i + 1
alist = [1, 2, 3, 4]
for x in addlist(alist):
    print(x)

结果：

2
3
4
5

2. next()语句

代码：

def h():
    print('Wen Chuan')
    yield 5
    print('Fighting!')
c = h()
c.__next__()# output:Wen Chuan
c.__next__()#因为后面没有yield了，所以会拋出异常

结果：

Traceback (most recent call last):
  File "E:/PyCharmProject/test.py", line 23, in <module>
    c.__next__()
StopIteration
Wen Chuan
Fighting!

3. send(msg) 与 next()

　　其实next()和send()在必定意义上做用是类似的，区别是send()能够传递yield表达式的值进去，而next()不能传递特定的值，只能传递None进去。所以，咱们能够看作c.next() 和 c.send(None) 做用是同样的。

代码：

def h():
    print('Wen Chuan')
    m = yield 5  # Fighting!
    print ('m:%s'%m)
    d = yield 12
    print ('We are together!')

c = h()
c.__next__()  #至关于c.send(None) output:Wen Chuan
r=c.send('Fighting!')  #(yield 5)表达式被赋予了'Fighting!'
print('r:%d'%r)#返回值为yield 12

结果:

Wen Chuan
m:Fighting!
r:12