Qaviton Handlers

error handling utilities

Installation

pip install --upgrade qaviton_handlers  

Requirements

• Python 3.6+

Features

• retry decorator ✓
• retry with context ✓
• try functions ✓
• catch errors ✓
• simple Exception wrapper ✓

Usage

def retry(tries=3, delay=0, backoff=1, jitter=0, max_delay=None, exceptions=Exception, logger: Logger = log):
    """Retry function decorator \ try a context of actions until attempts run out
    :param exceptions: an exception or a tuple of exceptions to catch. default: Exception.
    :param tries: the maximum number of attempts: -1 (infinite).
    :param delay: initial delay between attempts. default: 0.
    :param max_delay: the maximum value of delay. default: None (no limit).
    :param backoff: multiplier applied to delay between attempts. default: 1 (no backoff).
                    fixed if a number, random if a range tuple (min, max), functional if callable (function must receive **kwargs)
    :param jitter: extra seconds added to delay between attempts. default: 0.
                   fixed if a number, random if a range tuple (min, max), functional if callable (function must receive **kwargs)
    :param logger: logger.warning(fmt, error, delay) will be called on failed attempts.
                   default: retry.logging_logger. if None, logging is disabled."""

retry decorator

from qaviton_handlers.try_decorator import retry

@retry()
def foo():
    n = int('1'+input('select number:'))
    print(n)

foo()

retry with context

from qaviton_handlers.try_context import retry

with retry() as trying:
    while trying:
        with trying:
            print("Attempt #%d of %d" % (trying.attempt, trying.attempts))
            raise

using different try wrapper functions

from qaviton_handlers.try_functions import try_to, try_or_none, multi_try, multi_try_no_break

def foo(a=0):
    print(float(a+input("select number:")))

# simply try
try_to(foo, 1)
try_to(foo, 2)
try_to(foo, 3)

# get the error
error = try_to(foo, 4)
if error: print(error)

# if error occurred
if try_to(foo, 5):
    try_to(foo, 5)

# try with key arguments
r = try_to(lambda a,b,c:a*b*c, 1,kwargs={'b':2,'c':3})
print(r)

# try to get a number
number = try_or_none(lambda a:float(a+input("select number:")), 6)
if number: print(number)

# try many functions, return a list of results, or an error
# if an error occurred, the multi try stops
multi_try(
  lambda: foo(10), 
  lambda: foo(11), 
)

# specify errors to ignore
response = multi_try(
  lambda: foo(13),
  lambda: foo(14),
  exceptions=Exception,
)

# handle the error
response = multi_try(
  lambda: foo(13),
  lambda: foo(14),
)
if isinstance(response, Exception):
    ...

# try many functions, return a list of results, some may be errors
# if an error occurred, the multi try continues
multi_try_no_break(
    lambda: foo(8),
    lambda: foo(9),
    lambda: foo(0),
)

ignore errors now so you can handle them later

from qaviton_handlers.catch import Catch
from qaviton_handlers.utils.error import Error

catch = Catch(store=True)

# catch an error
try:
    1 + '1'
except Exception as e:
    catch(e)

# a cleaner syntax
with catch:
    1 + '1'
    2 + '2'

# ignore the error
with Catch():
    5 * 'e'

print(f"caught {catch.count} errors")
print(f"caught first {catch.first}")
print(f"caught last {catch.last}")

# make your own Catch
class MyCatch(Catch):
    def handler(self, e):
        self.stack.add(Error(e))
        if self.log:
            self.log.warning(f"I caught {e}")
        return self