python的迭代器,生成器和装饰器你了解吗

list1=[1,2,3]
s=iter(list1) # 创建迭代器对象
print(next(s)) # 输出迭代器的下一个元素
print(next(s))
print(next(s))

list2=[1,2,3,4,5]
s2 = iter(list2)    # 创建迭代器对象
for h in s2:
    print (h, end="-")

#注意括号
#列表生成式
lis = [x+x for x in range(5)]
print(lis)
#生成器
gen= (x+x for x in range(5))
print(gen)
# gen = (x+x for x in range(5))
# print(next(gen))
# print(next(gen))
# print(next(gen))
# print(next(gen))
# print(next(gen))
generator_ex = (x+x for x in range(5))
for i in generator_ex:
    print(i)

def frange(star,stop,step):
    x=star
    while x<stop:
        yield x
        x+=step
for i in frange(10,20,0.5):
    print(i)

def foo():
    print("starting...")
    while True:
        print("yield前")
        res = yield 4
        print("yield后")
        print("res:", res)
g = foo()
print(next(g))
print("*" * 20)
print(next(g))

# 这是装饰函数
def logger(func):
    def wrapper(*args, **kw):
        print('我准备开始计算：{} 函数了:'.fORMat(func.__name__))
        # 真正执行的是这行。
        func(*args, **kw)
        print('啊哈，我计算完啦。给自己加个鸡腿！！')
    return wrapper
@logger
def add(x, y):
    print('{} + {} = {}'.format(x, y, x+y))
add(200, 50)

# 这是装饰函数
def timer(func):
    def wrapper(*args, **kw):
        t1=time.time()
        # 这是函数真正执行的地方
        func(*args, **kw)
        t2=time.time()
        # 计算下时长
        cost_time = t2-t1
        print("花费时间：{}秒".format(cost_time))
    return wrapper
import time
@timer
def want_sleep(sleep_time):
    time.sleep(sleep_time)
want_sleep(10)

def american():
    print("我来自中国。")
def chinese():
    print("I am from America.")
def say_hello(contry):
    def wrapper(func):
        def deco(*args, **kwargs):
            if contry == "china":
                print("你好!")
            elif contry == "america":
                print('hello.')
            else:
                return
            # 真正执行函数的地方
            func(*args, **kwargs)
        return deco
    return wrapper
@say_hello("china")
def american():
    print("我来自中国。")
@say_hello("america")
def chinese():
    print("I am from America.")