[英]Repeat Python function call on exception?
嘿大家我正在研究数据抓取项目,如果引发异常,我正在寻找一种简洁的方法来重复函数调用。
伪代码:
try:
myfunc(x)
except myError:
###try to call myfunc(x) again Y number of times,
until success(no exceptions raised) otherwise raise myError2
我意识到这根本不是最佳实践,但我正在研究一些不可靠的不同代码/网络层,我无法实际调试它们。
现在我正在通过一系列尝试来完成这个尝试\\除了块,它让我的眼睛流血。
优雅的想法谁?
要做到你想要的,你可以做如下的事情:
import functools
def try_x_times(x, exceptions_to_catch, exception_to_raise, fn):
@functools.wraps(fn) #keeps name and docstring of old function
def new_fn(*args, **kwargs):
for i in xrange(x):
try:
return fn(*args, **kwargs)
except exceptions_to_catch:
pass
raise exception_to_raise
return new_fn
然后你只需将旧函数包装在这个新函数中:
#instead of
#risky_method(1,2,'x')
not_so_risky_method = try_x_times(3, (MyError,), myError2, risky_method)
not_so_risky_method(1,2,'x')
#or just
try_x_times(3, (MyError,), myError2, risky_method)(1,2,'x')
使用循环
i = 0
while True:
try: myfunc(x); break;
except myError:
i = i + 1;
# print "Trying again"
if i > 5: raise myError2;
for x in xrange(num_retries):
try:
myFunc()
except MyError, err:
continue
#time.sleep(1)
err = None
break
if err:
raise MyError2
#else:
# print "Success!"
在重试之后像往常一样提高异常
from functools import wraps
def retry(times):
"""
Decorator to retry any functions 'times' times.
"""
def retry_decorator(func):
@wraps(func)
def retried_function(*args, **kwargs):
for i in range(times - 1):
try:
func(*args, **kwargs)
return
except Exception:
pass
func(*args, **kwargs)
return retried_function
return retry_decorator
# test
attempts = 3
@retry(4)
def function_that_raises_error():
global attempts
if 0 < attempts:
print("fail")
attempts -= 1
raise Exception
print("pass")
function_that_raises_error()
我喜欢用递归来做这些问题:
def tryfor(times, on_failure, excepts, func, *args, **kwargs):
if times < 1:
raise on_failure()
try:
return func(*args, **kwargs)
except excepts:
return tryfor(times-1, on_failure, excepts, func, *args, **kwargs)
tryfor(3, PermanentException, (SomeError,), dostuff,1,2)
请尝试以下代码段:
while True:
try:
func()
break
except:
print "Error. Gonna try again"
但最好限制重试次数。
success = False
attempts = 0
while not success and attempts < 10: # or however many times you want to attempt
try:
functionCall()
success = True
except:
i += 1
if not success:
raise functionCallFailedError
希望这可以帮助
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