>>> def simple_coro2(a):
...     print('-> Started: a =', a)
...     b = yield a
...     print('-> Received: b =', b)
...     c = yield a + b
...     print('-> Received: c =', c)
...
>>> my_coro2 = simple_coro2(14)
>>> from inspect import getgeneratorstate
>>> getgeneratorstate(my_coro2)
'GEN_CREATED'
>>> next(my_coro2)
-> Started: a = 14
14
>>> getgeneratorstate(my_coro2)
'GEN_SUSPENDED'
>>> my_coro2.send(28)
-> Received: b = 28
42
>>> my_coro2.send(99)
-> Received: c = 99
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
StopIteration
>>> getgeneratorstate(my_coro2)
'GEN_CLOSED' 

def averager():
    total = 0.0
    count = 0
    average = None
    while True:
        term = yield average
        total += term
        count += 1
        average = total/count
 
>>> coro_avg = averager()
>>> next(coro_avg)   #調(diào)用 next 函數(shù)，預激協(xié)程
>>> coro_avg.send(10)
10.0
>>> coro_avg.send(30)
20.0
>>> coro_avg.send(5)
15.0

from functools import wraps
 
def coroutine(func):
    @wraps(func)
    def primer(*args,**kwargs):
        gen = func(*args,**kwargs)
        next(gen)
        return gen
    return primer    
 
@coroutine
def averager2():
    total = 0.0
    count = 0
    average = None
    while True:
        term = yield average
        total += term
        count += 1
        average = total/count
 
>>> coro_avg = averager()
>>> from inspect import getgeneratorstate
>>> getgeneratorstate(coro_avg)
'GEN_SUSPENDED'
>>> coro_avg.send(10)
10.0
>>> coro_avg.send(30)
20.0
>>> coro_avg.send(5)
15.0

>>> from coroaverager1 import averager
>>> coro_avg = averager()
>>> coro_avg.send(40)
40.0
>>> coro_avg.send(50)
45.0
>>> coro_avg.send('spam')
Traceback (most recent call last):
...
TypeError: unsupported operand type(s) for +=: 'float' and 'str'
>>> coro_avg.send(60)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
StopIteration

class DemoException(Exception):
    """為這次演示定義的異常類型。"""
    
def demo_exc_handling():
    print('-> coroutine started')
    while True:
        try:
            x = yield
        except DemoException:
            print('*** DemoException handled. Continuing...')
        else:
            print('-> coroutine received: {!r}'.format(x))
    raise RuntimeError('This line should never run.')
    
>>> exc_coro = demo_exc_handling()
>>> next(exc_coro)
-> coroutine started
>>> exc_coro.send(11)
-> coroutine received: 11
>>> exc_coro.send(22)
-> coroutine received: 22
 
>>> exc_coro.throw(DemoException)
*** DemoException handled. Continuing...
>>> getgeneratorstate(exc_coro)
'GEN_SUSPENDED'
 
>>> exc_coro.close()
>>> from inspect import getgeneratorstate
>>> getgeneratorstate(exc_coro)
'GEN_CLOSED'

from collections import namedtuple
Result = namedtuple('Result', 'count average')
 
def averager():
    total = 0.0
    count = 0
    average = None
    while True:
        term = yield
        if term is None:
            break
        total += term
        count += 1
        average = total/count
    return Result(count, average)
    
>>> coro_avg = averager()
>>> next(coro_avg)
>>> coro_avg.send(10)
>>> coro_avg.send(30)
>>> coro_avg.send(6.5)
>>> coro_avg.send(None)
Traceback (most recent call last):
...
StopIteration: Result(count=3, average=15.5)    

>>> try:
...    coro_avg.send(None)
... except StopIteration as exc:
...    result = exc.value
...
>>> result
Result(count=3, average=15.5)

>>> def gen():
... for c in 'AB':
...     yield c
... for i in range(1, 3):
...     yield i
...
>>> list(gen())
['A', 'B', 1, 2]

>>> def gen():
...     yield from 'AB'
...     yield from range(1, 3)
...
>>> list(gen())
['A', 'B', 1, 2]

from collections import namedtuple
 
Result = namedtuple('Result', 'count average')
 
# 子生成器
def averager():
    total = 0.0
    count = 0
    average = None
    while True:
        # main 函數(shù)發(fā)送數(shù)據(jù)到這里 
        print("in averager, before yield")
        term = yield
        if term is None: # 終止條件
            break
        total += term
        count += 1
        average = total/count
 
    print("in averager, return result")
    return Result(count, average) # 返回的Result 會成為grouper函數(shù)中yield from表達式的值
 
 
# 委派生成器
def grouper(results, key):
     # 這個循環(huán)每次都會新建一個averager 實例，每個實例都是作為協(xié)程使用的生成器對象
    while True:
        print("in grouper, before yield from averager, key is ", key)
        results[key] = yield from averager()
        print("in grouper, after yield from, key is ", key)
 
 
# 調(diào)用方
def main(data):
    results = {}
    for key, values in data.items():
        # group 是調(diào)用grouper函數(shù)得到的生成器對象
        group = grouper(results, key)
        print("\ncreate group: ", group)
        next(group) #預激 group 協(xié)程。
        print("pre active group ok")
        for value in values:
            # 把各個value傳給grouper 傳入的值最終到達averager函數(shù)中；
            # grouper并不知道傳入的是什么，同時grouper實例在yield from處暫停
            print("send to %r value %f now"%(group, value))
            group.send(value)
        # 把None傳入groupper，傳入的值最終到達averager函數(shù)中，導致當前實例終止。然后繼續(xù)創(chuàng)建下一個實例。
        # 如果沒有group.send(None)，那么averager子生成器永遠不會終止，委派生成器也永遠不會在此激活，也就不會為result[key]賦值
        print("send to %r none"%group)
        group.send(None)
    print("report result: ")
    report(results)
 
 
# 輸出報告
def report(results):
    for key, result in sorted(results.items()):
        group, unit = key.split(';')
        print('{:2} {:5} averaging {:.2f}{}'.format(result.count, group, result.average, unit))
 
 
data = {
    'girls;kg':[40, 41, 42, 43, 44, 54],
    'girls;m': [1.5, 1.6, 1.8, 1.5, 1.45, 1.6],
    'boys;kg':[50, 51, 62, 53, 54, 54],
    'boys;m': [1.6, 1.8, 1.8, 1.7, 1.55, 1.6],
}
 
if __name__ == '__main__':
    main(data) 

create group:  <generator object grouper at 0x7f34ce8458e0>
in grouper, before yield from averager, key is  girls;kg
in averager, before yield
pre active group ok
send to <generator object grouper at 0x7f34ce8458e0> value 40.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 41.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 42.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 43.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 44.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 54.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> none
in averager, return result
in grouper, after yield from, key is  girls;kg
in grouper, before yield from averager, key is  girls;kg
in averager, before yield
 
create group:  <generator object grouper at 0x7f34ce845678>
in grouper, before yield from averager, key is  girls;m
in averager, before yield
pre active group ok
send to <generator object grouper at 0x7f34ce845678> value 1.500000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845678> value 1.600000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845678> value 1.800000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845678> value 1.500000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845678> value 1.450000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845678> value 1.600000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845678> none
in averager, return result
in grouper, after yield from, key is  girls;m
in grouper, before yield from averager, key is  girls;m
in averager, before yield
 
create group:  <generator object grouper at 0x7f34ce845620>
in grouper, before yield from averager, key is  boys;kg
in averager, before yield
pre active group ok
send to <generator object grouper at 0x7f34ce845620> value 50.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845620> value 51.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845620> value 62.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845620> value 53.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845620> value 54.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845620> value 54.000000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce845620> none
in averager, return result
in grouper, after yield from, key is  boys;kg
in grouper, before yield from averager, key is  boys;kg
in averager, before yield
 
create group:  <generator object grouper at 0x7f34ce8458e0>
in grouper, before yield from averager, key is  boys;m
in averager, before yield
pre active group ok
send to <generator object grouper at 0x7f34ce8458e0> value 1.600000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 1.800000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 1.800000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 1.700000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 1.550000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> value 1.600000 now
in averager, before yield
send to <generator object grouper at 0x7f34ce8458e0> none
in averager, return result
in grouper, after yield from, key is  boys;m
in grouper, before yield from averager, key is  boys;m
in averager, before yield
report result: 
 6 boys  averaging 54.00kg
 6 boys  averaging 1.68m
 6 girls averaging 44.00kg
 6 girls averaging 1.58m

_i = iter(EXPR) 
try:
    _y = next(_i)
except StopIteration as _e:
    _r = _e.value
else:
    while 1:
        _s = yield _y
    try:
        _y = _i.send(_s)
    except StopIteration as _e:
        _r = _e.value
        break
RESULT = _r

_i = iter(EXPR)
try:
    _y = next(_i)
except StopIteration as _e:
    _r = _e.value
else:
    while 1:
        try:
            _s = yield _y
        except GeneratorExit as _e:
            try:
                _m = _i.close
            except AttributeError:
                pass
            else:
                _m()
            raise _e
        except BaseException as _e:
            _x = sys.exc_info()
            try:
                _m = _i.throw
            except AttributeError:
                raise _e
            else:
                try:
                    _y = _m(*_x)
                except StopIteration as _e:
                    _r = _e.value
                    break
        else:
            try:
                if _s is None:
                    _y = next(_i)
                else:
                    _y = _i.send(_s)
            except StopIteration as _e:
                _r = _e.value
                break
RESULT = _r