예외 후에 다시 시도하는 방법?

예외 후에 다시 시도하는 방법?

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로 시작하는 루프가 for i in range(0, 100)있습니다. 일반적으로 올바르게 실행되지만 네트워크 상태로 인해 실패하는 경우가 있습니다. 현재 나는 실패 continue했을 때 except 절 에 있도록 설정했습니다 (에 대한 다음 숫자로 계속 i).

동일한 번호를 다시 할당 i하고 루프의 실패한 반복을 다시 실행할 수 있습니까?

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를 수행 while True루프를 들어, 넣어 당신의 내부에 try그에서 코드 내부 및 휴식 while코드가 성공에만 루프.

for i in range(0,100):
    while True:
        try:
            # do stuff
        except SomeSpecificException:
            continue
        break

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재시도 횟수를 제한하여 특정 항목에 문제가있는 경우 다음 항목으로 계속 진행할 수 있습니다.

for i in range(100):
  for attempt in range(10):
    try:
      # do thing
    except:
      # perhaps reconnect, etc.
    else:
      break
  else:
    # we failed all the attempts - deal with the consequences.

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다시 시도 패키지는 실패 코드 블록을 재 시도 할 수있는 좋은 방법입니다.

예를 들면 다음과 같습니다.

@retry(wait_random_min=1000, wait_random_max=2000)
def wait_random_1_to_2_s():
    print("Randomly wait 1 to 2 seconds between retries")

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여기에 다른 솔루션과 유사한 솔루션이 있지만 규정 된 수 또는 재 시도에서 성공하지 못하면 예외가 발생합니다.

tries = 3
for i in range(tries):
    try:
        do_the_thing()
    except KeyError as e:
        if i < tries - 1: # i is zero indexed
            continue
        else:
            raise
    break

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추악한 while 루프를 사용하지 않는보다 "기능적인"접근 방식 :

def tryAgain(retries=0):
    if retries > 10: return
    try:
        # Do stuff
    except:
        retries+=1
        tryAgain(retries)

tryAgain()

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가장 명확한 방법은 명시 적으로 설정하는 것 i입니다. 예를 들면 다음과 같습니다.

i = 0
while i < 100:
    i += 1
    try:
        # do stuff

    except MyException:
        continue

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재귀 사용

for i in range(100):
    def do():
        try:
            ## Network related scripts
        except SpecificException as ex:
            do()
    do() ## invoke do() whenever required inside this loop

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시간 초과가있는 일반적인 솔루션 :

import time

def onerror_retry(exception, callback, timeout=2, timedelta=.1):
    end_time = time.time() + timeout
    while True:
        try:
            yield callback()
            break
        except exception:
            if time.time() > end_time:
                raise
            elif timedelta > 0:
                time.sleep(timedelta)

용법:

for retry in onerror_retry(SomeSpecificException, do_stuff):
    retry()

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Python Decorator Library 와 비슷한 것이 있습니다 .

예외를 테스트하지 않고 반환 값을 명심하십시오. 데코 레이팅 된 함수가 True를 반환 할 때까지 재 시도합니다.

약간 수정 된 버전이 트릭을 수행해야합니다.

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for _ in range(5):
    try:
        # replace this with something that may fail
        raise ValueError("foo")

    # replace Exception with a more specific exception
    except Exception as e:
        err = e
        continue

    # no exception, continue remainder of code
    else:
        break

# did not break the for loop, therefore all attempts
# raised an exception
else:
    raise err

My version is similar to several of the above, but doesn't use a separate while loop, and re-raises the latest exception if all retries fail. Could explicitly set err = None at the top, but not strictly necessary as it should only execute the final else block if there was an error and therefore err is set.

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Using while and a counter:

count = 1
while count <= 3:  # try 3 times
    try:
        # do_the_logic()
        break
    except SomeSpecificException as e:
        # If trying 3rd time and still error?? 
        # Just throw the error- we don't have anything to hide :)
        if count == 3:
            raise
        count += 1

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You can use Python retrying package. Retrying

It is written in Python to simplify the task of adding retry behavior to just about anything.

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If you want a solution without nested loops and invoking break on success you could developer a quick wrap retriable for any iterable. Here's an example of a networking issue that I run into often - saved authentication expires. The use of it would read like this:

client = get_client()
smart_loop = retriable(list_of_values):

for value in smart_loop:
    try:
        client.do_something_with(value)
    except ClientAuthExpired:
        client = get_client()
        smart_loop.retry()
        continue
    except NetworkTimeout:
        smart_loop.retry()
        continue

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I use following in my codes,

   for i in range(0, 10):
    try:
        #things I need to do
    except ValueError:
        print("Try #{} failed with ValueError: Sleeping for 2 secs before next try:".format(i))
        time.sleep(2)
        continue
    break

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i recently worked with my python on a solution to this problem and i am happy to share it with stackoverflow visitors please give feedback if it is needed.

print("\nmonthly salary per day and year converter".title())
print('==' * 25)


def income_counter(day, salary, month):
    global result2, result, is_ready, result3
    result = salary / month
    result2 = result * day
    result3 = salary * 12
    is_ready = True
    return result, result2, result3, is_ready


i = 0
for i in range(5):
    try:
        month = int(input("\ntotal days of the current month: "))
        salary = int(input("total salary per month: "))
        day = int(input("Total Days to calculate> "))
        income_counter(day=day, salary=salary, month=month)
        if is_ready:
            print(f'Your Salary per one day is: {round(result)}')
            print(f'your income in {day} days will be: {round(result2)}')
            print(f'your total income in one year will be: {round(result3)}')
            break
        else:
            continue
    except ZeroDivisionError:
        is_ready = False
        i += 1
        print("a month does'nt have 0 days, please try again")
        print(f'total chances left: {5 - i}')
    except ValueError:
        is_ready = False
        i += 1
        print("Invalid value, please type a number")
        print(f'total chances left: {5 - i}')

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Here's my idea on how to fix this:

j = 19
def calc(y):
    global j
    try:
        j = j + 8 - y
        x = int(y/j)   # this will eventually raise DIV/0 when j=0
        print("i = ", str(y), " j = ", str(j), " x = ", str(x))
    except:
        j = j + 1   # when the exception happens, increment "j" and retry
        calc(y)
for i in range(50):
    calc(i)

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increment your loop variable only when the try clause succeeds

참고URL : https://stackoverflow.com/questions/2083987/how-to-retry-after-exception