FYI, default here is unused.
On Sun, 23 May 2021 at 14:29, Ricky Teachey via Python-ideas <
[email protected]> wrote:
> I think you can already do all of this with a custom exception-swallowing
> decorator function.
>
> Something like this:
>
> from functools import wraps
>
> def swallow(*exceptions, default=Exception, result=None):
> if not exceptions:
> exceptions = Exception,
> def decorator(func):
> @wraps(func)
> def wrapped(*args, **kwargs):
> try:
> return func(*args, **kwargs)
> except exceptions:
> return result
> return wrapped
> return decorator
>
> Then just write:
>
> @swallower()
> def some_func():
> log_to_telegram('This is a not important message. It's okay even if
> it isn\'t delivered.')
>
> For divide by zero errors you need to put the division operation in a
> lambda function:
>
> safe_divide = swallow(DivideByZero, result=0)
> division = safe_divide(lambda: a/b)
>
> I didn't test any of this but it should be working.
>
> On Sun, May 23, 2021, 8:54 AM Shivam Saini <[email protected]> wrote:
>
>> Sometimes, we need to execute a statement, which might throw an exception
>> and we want to return None if it causes an exception. In short, we want to
>> run that command as failsafe mode, so that it doesn't cause abnormal
>> termination in case of any exception.
>>
>> *Approach till now:*
>>
>> def log_to_telegram(text):
>> ''' Suppose you want to send some log to some telegram channel using
>> telegram bot api. It might raise Network Error, or Invalid Bot token error.
>> '''
>> send_message(CHANNEL, BOT_TOKEN, TEXT) # Suppose send_message is a
>> function wrapper for telegram bot api.
>>
>> def some_func():
>> try:
>> log_to_telegram('This is a not important message. It's okay even
>> if it isn\'t delivered.')
>> except:
>> pass
>> # Next work
>>
>> *Suggested approach:*
>>
>> # consider the same log_to_telegram function as defined in previous
>> example
>>
>> def some_func():
>> safe log_to_telegram('This is a not important message. It's okay even
>> if it isn\'t delivered.')
>> # safe keyword ensures that it raises no exception and the process
>> isn't terminated even if log_to_telegram function raises an exception.
>>
>> *Other examples:*
>>
>> *1. By default, it will return None.*
>> * Example: *
>> try:
>> file = open('some_file')
>> except:
>> file = None
>> * Can be rewritten as:*
>> file = safe open('some_file')
>>
>> *2. We can provide a return value explicitly which should be returned in
>> case of some exception.*
>> * Example: *
>> try:
>> division = a/b
>> except:
>> division = 0
>> * Can be rewritten as:*
>> division = safe(0) a/b
>>
>> *3. We can set what exceptions we want to be 'safed'.*
>> * Example: *
>> try:
>> element = some_list[index]/divisor
>> except ZeroDivisionError:
>> element = 0 # It will make element zero if divisor is zero,
>> but it will not except IndexError in case index is out of range for
>> some_list
>> * Can be rewritten as:*
>> element = safe(0, ZeroDivisionError) some_list[index]/divisor
>>
>> *I think this keyword should be there in python, it will make code short
>> and readable. *
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