def

Posted 2021-12-12 zhangchen-sx

# 函数

# 修改全局变量
a = 10 
def func():
    global a
    a = 20
print(a)  #10
func()
print(a)  #20
-----------------
# 外部访问局部变量
def outer():
    a = 10
    def func():
        nonlocal a
        a = 20
    return a
def func():
    b = outer()
    return b
print(func()) #10

# 1 返回函数名
def outer():
    def inner():
        print("我是inner")
    return inner
ret = outer()
ret()
# 2 闭包 里面用到了外面的变量
def func():
    a = 10
    def inner(): #定义inner
        print(a)
    inner() #调用inner
    print(inner.__closure__)  # 能打印出东西就是闭包
func()

#装饰器
def wrapper(fn):
    def inner(*args,**kwargs):
        print(‘进站‘)
        ret = fn(*args,**kwargs)
        print(‘出检票‘)
    return inner

@wrapper
def train():
    print(‘坐火车去拉萨‘)

@wrapper
def bus():
    print(‘座公交车去拉萨‘)

train()
bus()

lst = ["张无忌", "胡辣汤", "赵敏", "灭绝"]
# for循环的本质
it = lst.__iter__() #  for循环的内部是用迭代器来获取数据的
while 1:
    try:
        item = it.__next__()
        print(item)
    except StopIteration:
        print("结束了")
        break

def order():  
    lst = []
    for i in range(10000):
        lst.append("衣服%s" % i)
    return lst
ret = order()
print(ret[0])
# 下面生成器  工厂生产衣服的例子
def order():
    for i in range(10000):
        yield "衣服%s" % i
gen = order()
print(next(gen))
print(gen.__next__())

# 生成器send 的传值的例子
def eat():
    print("韭菜盒子")
    a = yield "红烧肉"
    print(a)
    b = yield "吱吱冒油的大肘子"
    print(b)  # 绿豆汤
    c = yield "地三鲜"
    print(c)  # 红豆汤

g=eat()
print("外面打印:" + g.__next__())     # yield "红烧肉"
print("外面打印:" + g.send("疙瘩汤")) # yield "吱吱冒油的大肘子"
print("外面打印:" + g.send("绿豆汤")) # yield "地三鲜"
print("外面打印:" + g.send("红豆汤")) # 报错

def add(a, b):
    return a + b

def gen_fun():  # 0 1 2 3
    for i in range(4):
        yield i

g = gen_fun()   # 0 1 2 3

n=3
g = (add(i,5) for i in g)
n=5
g = (add(i,5) for i in g)
#
# for n in [3, 5]:
#     g = (add(i, n) for i in g)

print(list(g)) #[10, 11, 12, 13]