这个python装饰器有什么问题？

Question

I have the following decorator that should handle "no network" exceptions:

class NetworkError(RuntimeError):
    pass

def reTryer(max_retries=5, timeout=5):
    def wraper(func):
        request_exceptions = (
            requests.exceptions.Timeout,
            requests.exceptions.ConnectionError,
            requests.exceptions.HTTPError
        )
        def inner(*args, **kwargs):
            for i in range(max_retries):
                try:
                    result = func(*args, **kwargs)
                except request_exceptions:
                    time.sleep(timeout)
                    print("Bad or broken connection, trying again...")
                    continue
                else:
                    return result
            else:
                raise NetworkError
        return inner
    return wraper

But it doesn't work at all, there is even no "Bad or broken connection, trying again..." output when my LAN adapter is in disconnected state, it just shows nothing. This is func definition and call:

@reTryer(5,5)
def func(arg):
    #some code

func(arg)

Am I missing something?

Answer 1

To answer your question:

As the implementation seems correct, I can imagine some things which could be the cause of the problem.

Mainly I think about the decorated function never returning, throwing a different exception than you had in focus, or even returning normal.

You could test this with

@reTryer(2, 1.0)
def always_ok():
    print "ok"

@reTryer(2, 1.0)
def always_good_error():
    print "good error"
    raise requests.exceptions.Timeout

@reTryer(2, 1.0)
def always_bad_error():
    print "bad error"
    raise RuntimeError

I get

>>> always_ok()
ok
>>> import time
>>> always_good_error()
good error
Bad or broken connection, trying again...
good error
Bad or broken connection, trying again...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 17, in inner
__main__.NetworkError
>>> always_bad_error()
bad error
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 9, in inner
  File "<stdin>", line 4, in always_bad_error
RuntimeError
>>>