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def consumer():
    r_msg = ''
    while True:
        n = yield r_msg
        if not n:
            # print('n is None or Empty') throw StopIteration
            return
        print('consumer() %d' % n)
        r_msg = 'ok'

# n = yield value
# 包含了3个步骤：
# 1.向函数外抛出（返回）value
# 2.暂停(pause)，等待next()或send()恢复
# 3.赋值 n=MockGetValue()，这个MockGetValue()是假想函数，
# 用来接收send()发送进来的值


def produce(cmer):
    cmer.send(None) # if delete, throw TypeError: can't send non-None value to a just-started generator
    n = 0
    while n < 5:
        n += 1
        print('produce() producing %d' % n)
        r_msg = cmer.send(n)
        print('produce() receive msg from consumer: %s' % r_msg)
    cmer.close()

# 在produce()，通过cmer.send(None)或者next(cmer)启动生成器函数，
# consumer()执行到第一个yield语句结束的位置。

# 此时，n = yield r_msg 仅执行了 1.向函数外抛出（返回）value 
# 2.暂停(pause)，等待next()或send()恢复
# 特别注意是，n = yield r_msg 还没有执行 3.赋值 n=MockGetValue()

# 当在produce()执行cmer.send(n)时候，传入后，在consumer()中 
# n = yield r_msg 开始执行 3.赋值 n=MockGetValue()



c = consumer()
produce(c)

def gen_yield():
    yield range(5)


def gen_yield_from():
    yield from range(5)


g_yield = gen_yield()
g_yield_from = gen_yield_from()

for g in g_yield:
    print(g)

print('====================')
for g in g_yield_from:
    print(g)

range(0, 5)
====================
0
1
2
3
4

def fab(max):
    n, a, b = 0, 0, 1
    while n < max:
        yield b
        # print b
        a, b = b, a + b
        n = n + 1


def wrap_iterable(it):
    yield from it


generator = fab(5)
for f in wrap_iterable(generator):
    print(f)

1
1
2
3
5

@asyncio.coroutine
def smart_fib(n):
    index = 0
    a = 0
    b = 1
    while index < n:
        sleep_secs = random.uniform(0, 0.2)
        yield from asyncio.sleep(sleep_secs)  # 通常yield from后都是接的耗时操作
        print('Smart think {} secs to get {}'.format(sleep_secs, b))
        a, b = b, a + b
        index += 1

# yield from后面接的asyncio.sleep()是一个coroutine(里面也用了yield from)，
# 所以线程不会等待asyncio.sleep()，而是直接中断并执行下一个消息循环。
# 当asyncio.sleep()返回时，线程就可以从yield from拿到返回值（此处是None），然后接着执行下一行语句。 

# asyncio是一个基于事件循环的实现异步I/O的模块。
# 通过yield from，我们可以将协程asyncio.sleep的控制权交给事件循环，然后挂起当前协程，
# 之后由事件循环决定何时唤醒asyncio.sleep,接着向后执行代码。 
# 协程之间的调度都是由事件循环决定。

# 特别注意，yield from asyncio.sleep(sleep_secs) 这里不能用time.sleep(1)因为time.sleep()返回的是None，
# 它不是iterable，否则抛出异常 TypeError: ‘NoneType’ object is not iterable


@asyncio.coroutine
def stupid_fib(n):
    index = 0
    a = 0
    b = 1
    while index < n:
        sleep_secs = random.uniform(0, 0.4)
        yield from asyncio.sleep(sleep_secs)  # 通常yield from后都是接的耗时操作
        print('Stupid think {} secs to get {}'.format(sleep_secs, b))
        a, b = b, a + b
        index += 1


loop = asyncio.get_event_loop()
tasks = [
    smart_fib(5),
    stupid_fib(5),
]
loop.run_until_complete(asyncio.wait(tasks))
print('All fib finished.')
loop.close()

Stupid think 0.08516295175908538 secs to get 1
Smart think 0.1537956191924291 secs to get 1
Smart think 0.12929758554701115 secs to get 1
Stupid think 0.2892256222928606 secs to get 1
Smart think 0.17164449165156828 secs to get 2
Smart think 0.16220980840025945 secs to get 3
Stupid think 0.27210541712117337 secs to get 2
Smart think 0.1715009248020697 secs to get 5
Stupid think 0.2023469563932653 secs to get 3
Stupid think 0.3009223257835448 secs to get 5
All fib finished.

async def smart_fib(n):
    index = 0
    a = 0
    b = 1
    while index < n:
        sleep_secs = random.uniform(0, 0.2)
        await asyncio.sleep(sleep_secs)
        print('Smart think {} secs to get {}'.format(sleep_secs, b))
        a, b = b, a + b
        index += 1


async def stupid_fib(n):
    index = 0
    a = 0
    b = 1
    while index < n:
        sleep_secs = random.uniform(0, 0.2)
        await asyncio.sleep(sleep_secs)
        print('Stupid think {} secs to get {}'.format(sleep_secs, b))
        a, b = b, a + b
        index += 1


loop = asyncio.get_event_loop()
tasks = [
    smart_fib(5),
    stupid_fib(5),
]
loop.run_until_complete(asyncio.wait(tasks))
loop.close()

Smart think 0.00882750921810851 secs to get 1
Smart think 0.04897605243502872 secs to get 1
Stupid think 0.14133676443250204 secs to get 1
Smart think 0.09460081340195459 secs to get 2
Smart think 0.10392360738913782 secs to get 3
Stupid think 0.15655241126836938 secs to get 1
Stupid think 0.07286491653845838 secs to get 2
Smart think 0.18776425866569166 secs to get 5
Stupid think 0.1964418153612619 secs to get 3
Stupid think 0.010708925895951162 secs to get 5

url = 'https://www.archdaily.com/search/projects/categories/adaptive-reuse?page=22'
parseResult = parse.urlparse(url)
print(parseResult)