生成器

 1 #!/usr/bin/env python
 2 #created by Baird
 3 
 4 array = (i*2 for i in range(10))
 5 
 6 print(array.__next__())  #在循环之后调用next方法会报错，输出0
 7 print(array.__next__())     #输出2
 8 print(array.__next__())     #输出4
 9 
10 for i in array:          #生成器对象无法使用下标调用
11     print(i)            #输出6-18
12 
13 def fib(max):           #创建一个生成器
14     n,a,b=0,0,1
15     while n<max:
16         yield b         #中断，接收到 next() 或 send()时恢复中断
17         a,b=b,a+b
18         n=n+1
19     return("done")      #用于捕捉异常，判断生成器边界
20 
21 f = fib(5)
22 print("\n",f)
23 
24 while True:
25     try:
26         a = next(f)
27     except StopIteration as e:      #捕捉异常
28         print(e.value)
29         break