python 生成器

# 列表生成器
a = [x for x in range(10)]
print(a)

# 生成器对象的2种定义方法
#1 
def add(a):
    return a+a

b = (add(x) for x in range(5))

#2 yield
# 生成器的3种访问方法
#1 
print(next(g))
#2
for i in g:
    print(i)
#3
g.send(None)
g.send('text')

##########1##########
def foo():
    print('foo1...')
    yield 1
    print('foo2...')
    yield 2

g = foo()
print(g)
# print(next(g))
# print(next(g))

for i in g:
    print(i)


##########2##########

def add(a):
    return a+a

b = (add(x) for x in range(5))

print(b)
print(next(b))
print(next(b))

--------------send

def foo():
    print('ok1')
    count = yield 1
    print(count)
    print('ok2')
    yield 2

g = foo()
#next(g)
g.send(None)   # 先执行到yield 1之后
g.send('text')   # 从将‘text’赋值给count，再执行到yield 2之后