def generator_func():      print('a')      yield 1    g = generator_func()  print(g)

>>> <generator object generator_func at 0x10e178b88>

def generator_func():      print('a')      yield 1      g = generator_func()  ret1 = next(g)  print(ret1)

>>>
a
1

def generator_func():      print('a')      yield 1      print('b')      yield 2      print('c')      yield 3      print('d')    g = generator_func()  ret1 = next(g)  print(ret1)  ret2 = next(g)  print(ret2)  ret3 = next(g)  print(ret3)

>>>

  a
  1
  b
  2
  c
  3

def generator_func():      print('a')      yield 1      print('b')      yield 2      print('c')      yield 3      print('d')    g = generator_func()  ret1 = next(g)  print(ret1)  ret2 = next(g)  print(ret2)  ret3 = next(g)  print(ret3)  next(g)

next和StopIteration

import numbers  def cal_sum():      sum_num = 0      while True:          num = yield          if isinstance(num,numbers.Integral):              sum_num += num              print('sum :',sum_num)          elif num is None:              break    g = cal_sum()  g.send(None)   # 相当于next(g),预激活生成器  g.send(31)  g.send(25)  g.send(17)  g.send(8)    >>>  sum : 31  sum : 56  sum : 73  sum : 81

import numbers  def cal_sum():      sum_num = 0      while True:          num = yield          if isinstance(num,numbers.Integral):              sum_num += num              print('sum :',sum_num)          elif num is None:              break      return sum_num    g = cal_sum()  g.send(None)   # 相当于next(g),预激活生成器  g.send(31)  g.send(25)  g.send(17)  g.send(8)  g.send(None)   # 停止生成器    >>>  sum : 31  sum : 56  sum : 73  sum : 81  Traceback (most recent call last):    File "/Users/jingliyang/PycharmProjects/python的进阶/manager.py", line 19, in <module>      g.send(None)  StopIteration: 81

import numbers  def cal_sum():      sum_num = 0      while True:          num = yield          if isinstance(num,numbers.Integral):              sum_num += num              print('sum :',sum_num)          elif num is None:              break      return sum_num    g = cal_sum()  g.send(None)   # 相当于next(g),预激活生成器  g.send(31)  g.send(25)  g.send(17)  g.send(8)  try:      g.send(None)   # 停止生成器  except StopIteration as e:      print(e.value)

异常处理以及获取return的值

def throw_test():      print('a')      yield 1      print('b')      yield 2    g = throw_test()  next(g)  g.throw(Exception,'value error')

>>>
a
Traceback (most recent call last):
File "/Users/jingliyang/PycharmProjects/python的进阶/manager.py", line 32, in <module>
g.throw(ValueError,'value error')  # throw和send、next相同，都是驱动生成器继续执行，只不过throw用来向生成器中抛一个异常
File "/Users/jingliyang/PycharmProjects/python的进阶/manager.py", line 26, in throw_test
yield 1
ValueError: value error

def throw_test():      print('a')      try:          yield 1      except ValueError:          pass      print('b')      yield 2    g = throw_test()  next(g)  ret = g.throw(ValueError,'value error')  # throw和send、next相同，都是驱动生成器继续执行，只不过throw用来向生成器中抛一个异常  print(ret)    >>>  a  b  2

throw+异常处理

def throw_test():      print('a')      yield 1      print('b')      yield 2    g = throw_test()  ret1 = next(g)  print(ret1)  g.close()  next(g)    >>>  a  1  Traceback (most recent call last):    File "/Users/jingliyang/PycharmProjects/python的进阶/manager.py", line 45, in <module>      next(g)  StopIteration

l = ['h','e','l']  dic = {'l':'v1','o':'v2'}  s = 'eva'  def yield_from_gen():      for i in l:          yield i      for j in dic:          yield j      for k in s:          yield k  for item in yield_from_gen():      print(item,end='')    >>>helloeva    l = ['h','e','l']  dic = {'l':'v1','o':'v2'}  s = 'eva'  def yield_from_gen():      yield from l      yield from dic      yield from s  for item in yield_from_gen():      print(item,end='')    >>>helloeva

from itertools import chain  l = ['h','e','l']  dic = {'l':'v1','o':'v2'}  s = 'eva'  def yield_from_gen():      yield from chain(l,dic,s)    for item in yield_from_gen():      print(item,end='')

chain和yield from

def son_gen():      avg_num = 0      sum_num = 0      count = 1      while True:          num = yield avg_num          if num:              sum_num += num              avg_num = sum_num/count              count += 1          else:break      return avg_num    def depute_gen(key):      while True:          ret = yield from son_gen()          print(key,ret)    def main():      shares_list= {          'sogou':[6.4,6.5,6.6,6.2,6.1,6.6,6.7],          'alibaba':[181.72,184.58,183.54,180,88,169.88,178.21,189.32],          '美团':[59.7,52.6,47.2,55.4,60.7,66.1,74.0]      }      for key in shares_list:          g = depute_gen(key)          next(g)          for v in shares_list[key]:              g.send(v)          g.send(None)    main()

#基于yield实现异步  import time  def consumer():      '''任务1:接收数据,处理数据'''      while True:          x=yield    def producer():      '''任务2:生产数据'''      g=consumer()      next(g)      for i in range(10000000):          g.send(i)    producer()

import datetime  import heapq    # 堆模块  import types  import time      class Task:      def __init__(self, wait_until, coro):          self.coro = coro          self.waiting_until = wait_until        def __eq__(self, other):          return self.waiting_until == other.waiting_until        def __lt__(self, other):          return self.waiting_until < other.waiting_until      class SleepingLoop:        def __init__(self, *coros):          self._new = coros          self._waiting = []        def run_until_complete(self):          for coro in self._new:              wait_for = coro.send(None)              heapq.heappush(self._waiting, Task(wait_for, coro))          while self._waiting:              now = datetime.datetime.now()              task = heapq.heappop(self._waiting)              if now < task.waiting_until:                  delta = task.waiting_until - now                  time.sleep(delta.total_seconds())                  now = datetime.datetime.now()              try:                  print('*'*50)                  wait_until = task.coro.send(now)                  print('-'*50)                  heapq.heappush(self._waiting, Task(wait_until, task.coro))              except StopIteration:                  pass

def sleep(seconds):      now = datetime.datetime.now()      wait_until = now + datetime.timedelta(seconds=seconds)      print('before yield wait_until')      actual = yield wait_until   # 返回一个datetime数据类型的时间      print('after yield wait_until')      return actual - now      def countdown(label, length, *, delay=0):      print(label, 'waiting', delay, 'seconds before starting countdown')      delta = yield from sleep(delay)      print(label, 'starting after waiting', delta)      while length:          print(label, 'T-minus', length)          waited = yield from sleep(1)          length -= 1      print(label, 'lift-off!')      def main():      loop = SleepingLoop(countdown('A', 5), countdown('B', 3, delay=2),                          countdown('C', 4, delay=1))      start = datetime.datetime.now()      loop.run_until_complete()      print('Total elapsed time is', datetime.datetime.now() - start)      if __name__ == '__main__':      main()

# 例1  async def download(url):   # 加入新的关键字 async ，可以将任何一个普通函数变成协程      return 'eva'    ret = download('http://www.baidu.com/')  print(ret)  # <coroutine object download at 0x108b3a5c8>  ret.send(None)  # StopIteration: eva    # 例2  async def download(url):      return 'eva'  def run(coroutine):      try:          coroutine.send(None)      except StopIteration as e:          return e.value    coro = download('http://www.baidu.com/')  ret = run(coro)  print(ret)

# 例3  import types    @types.coroutine      # 将一个生成器变成一个awaitable的对象  def downloader(url):      yield 'aaa'      async def download_url(url):   # 协程      waitable = downloader(url)      print(waitable)   # <generator object downloader at 0x1091e2c78>     生成器      html = await waitable      return html    coro = download_url('http://www.baidu.com')  print(coro)                # <coroutine object download_url at 0x1091c9d48>  ret = coro.send(None)  print(ret)

import asyncio    @asyncio.coroutine  def hello():      print("Hello world!")      # 异步调用asyncio.sleep(1):      r = yield from asyncio.sleep(1)      print("Hello again!")    # 获取EventLoop:  loop = asyncio.get_event_loop()  # 执行coroutine  loop.run_until_complete(hello())  loop.close()

import asyncio    async def hello():      print("Hello world!")      # 异步调用asyncio.sleep(1):      r = await asyncio.sleep(1)      print("Hello again!")    # 获取EventLoop:  loop = asyncio.get_event_loop()  # 执行coroutine  loop.run_until_complete(hello())  loop.close()

import asyncio    async def hello():      print("Hello world!")      await asyncio.sleep(1)      print("Hello again!")      return 'done'    loop = asyncio.get_event_loop()  loop.run_until_complete(asyncio.wait([hello(),hello()]))  loop.close()

import asyncio    async def hello():      print("Hello world!")      await asyncio.sleep(1)      print("Hello again!")      return 'done'    loop = asyncio.get_event_loop()  task = loop.create_task(hello())  loop.run_until_complete(task)  ret = task.result()  print(ret)

import asyncio    async def hello(i):      print("Hello world!")      await asyncio.sleep(i)      print("Hello again!")      return 'done',i    loop = asyncio.get_event_loop()  task1 = loop.create_task(hello(2))  task2 = loop.create_task(hello(1))  task_l = [task1,task2]  tasks = asyncio.wait(task_l)  loop.run_until_complete(tasks)  for t in task_l:      print(t.result())

import asyncio    async def hello(i):      print("Hello world!")      await asyncio.sleep(i)      print("Hello again!")      return 'done',i    async def main():      tasks = []      for i in range(20):          tasks.append(asyncio.ensure_future(hello((20-i)/10)))      for res in asyncio.as_completed(tasks):          result = await res          print(result)  loop = asyncio.get_event_loop()  loop.run_until_complete(main())

import asyncio    async def get_url():      reader,writer = await asyncio.open_connection('www.baidu.com',80)      writer.write(b'GET / HTTP/1.1rnHOST:www.baidu.comrnConnection:closernrn')      all_lines = []      async for line in reader:          data = line.decode()          all_lines.append(data)      html = 'n'.join(all_lines)      return html    async def main():      tasks = []      for url in range(20):          tasks.append(asyncio.ensure_future(get_url()))      for res in asyncio.as_completed(tasks):          result = await res          print(result)      if __name__ == '__main__':      loop = asyncio.get_event_loop()      loop.run_until_complete(main())  # 处理一个任务      loop.run_until_complete(asyncio.wait([main()]))  # 处理多个任务        task = loop.create_task(main())  # 使用create_task获取返回值      loop.run_until_complete(task)      loop.run_until_complete(asyncio.wait([task]))