python生成器学习：

案例分析一：

def demo():    for i in range(4):        yield ig=demo()g1=(i for i in g)  #（i for i in demo()）g2=(i for i in g1) #(i for i in  （i for i in demo()）) --->print(list(g1))  #list(（i for i in demo()）)   #执行后   list((0,1,2,3)) --->[0,1,2,3]print(list(g2)) #因为g1生成器（i for i in demo()）已经使用，所有为空（），--->g2=(i for i in ())=()--->所以list(g2)=[]--------结果：[0, 1, 2, 3][]

案例分析二：

def add(n,i):    return n+idef test():    for i in range(4):        yield ig=test() # (i for i in range(4))for n in [1,10]:    g=(add(n,i) for i in g)#print(list(g))-----------结果：[20, 21, 22, 23]#解析：-------n=1g=(add(n+i)for i in (i for i in range(4)) )n=10g=(add(n+i)for i in (add(n+i)for i in (i for i in range(4)) ) )g:(add(n+i)for i in (add(n+i)for i in (0,1,2,3) ) )--->n=10 解：--->g=(add(10+i)for i in (add(10+i)for i in (0,1,2,3) ) )--->g=(add(10+i)for i in (10,11,12,13) )--->g=(20,21,22,23)--->list(g)=[20,21,22,23]