python协程

正在看《流畅的python》这本书，看到协程这个章节，先记录个很好的例子，后续详细补充读书笔记

• 定义一个计算移动平均值的协程

def gen_average():
    total = 0.0
    count = 0
    average = None
    while True:
        item = yield average
        total += item 
        count += 1
        average = total / count

gen_average_obj = gen_average() 
next(gen_average_obj)     # 使用next函数预激协程，也可以使用gen_average_obj.send(None)来预激
gen_average_obj.send(2) # 2.0
gen_average_obj.send(4) # 3.0

• 预激协程的装饰器
  预激是要让程序走到yield那一步，所以调用.send(x)之前一定记得要执行next(my_coro)

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 gen_average():
    total = 0.0
    count = 0
    average = None
    while True:
        item = yield average
        total += item 
        count += 1
        average = total / count

coro_avg = gen_average()
from inspect import getgeneratorstate # 这个貌似是py3开始有的内置库，py2.7会报错
getgeneratorstate(coro_avg)  # 'GEN_SUSPENDED'
coro_avg.send(10)  # 10.0
coro_avg.send(4)  # 7.0