在Python中装饰生成器:在生成之间调用某个方法

我发现了一些关于在Python中装饰生成器函数的非常有用的信息 here 使用 yield from

def mydec(func):
    def wrapper(*args, **kwargs):
        print(f'Getting values from "{func.__name__}"...')
        x = yield from func(*args, **kwargs)
        print(f'Got value {x}')
        return x
    return wrapper

@mydec
def mygen(n):
    for i in range(n):
        yield i

但是,这似乎只允许在生成器生命周期的开始和结束时添加装饰行为:

>>> foo = mygen(3)
>>> x = next(foo)
Getting values from "mygen"...
>>> x
0
>>> x = next(foo)
>>> x
1
>>> x = next(foo)
>>> x
2
>>> x = next(foo)
Got value None
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration
>>> x
2

不过,我对每次生成器生成时使用decorator来实现某些行为很感兴趣。但是,装饰程序不应该修改从生成器获取的值。例如,我希望输出:

>>> foo = mygen(3)
>>> x = next(foo)
Getting values from "mygen"...
Got value 0
>>> x
0
>>> x = next(foo)
Got value 1
>>> x
1
>>> x = next(foo)
Got value 2
>>> x
2

所以,打电话给 print 发生在每个屈服点,但屈服值保持不变。