CODEWITHSUNDEEP
pythonpython-2.7
sds
sds

Reputation: 60044

Python idiom for for error checking in a loop

I have a loop which looks like this:

errors += 1
for ...:
    ...
    if ...:
        logger.error(...)
        errors += 1
        continue
    ...
    if ...:
        logger.error(...)
        errors += 1
        continue
    ...
    if ...:
        logger.error(...)
        errors += 1
        continue
    ...
logger.info("%d errors",errors)

I wonder what the pythonic way to make it more readable is.

I can do

def e (fmt, *args):
    logger.error(fmt, *args)
    errors += 1
for ...:
    ...
    if ...:
        e(...)
        continue
    ...
    if ...:
        e(...)
        continue
    ...
    if ...:
        e(...)
        continue
    ...
logger.info("%d errors",errors)

or even

def e (cond, fmt, *args):
    if cond:
        logger.error(fmt, *args)
        errors += 1
    return cond
for ...:
    ...
    if e(...):
        continue
    ...
    if e(...):
        continue
    ...
    if e(...)
        continue
    ...
logger.info("%d errors",errors)

however, it doesn't look like I can do any better (no way to continue from inside e).

Right?

(I think I can raise StopIteration in e to abort the iteration, but not something like a non-existent ContinueIteration).

Upvotes: 2

Views: 69

Answers (2)

Tadhg McDonald-Jensen
Tadhg McDonald-Jensen

Reputation: 21453

you could create a wrapper for the logger that record how many times error is called:

class CountingLogger:
    def __init__(self, real_logger, initial_errors=0):
        self.logger = real_logger
        self.errors = initial_errors
    def error(self, *args, **kw):
        self.logger.error(*args, **kw)
        self.errors += 1

Then you'd use something like e = CountingLogger(logger) and call e.error() inside the loop and afterwards you can access e.errors to see how many times it was called. (naming could be better, error the method and errors the property are a bit too close for comfort)

Upvotes: 0

user2390182
user2390182

Reputation: 73470

Feels to me like using exception handling is semantically appropriate and similarly concise as a function without the need for any continue:

for ...:
    try:
        # ...
        if ...:
            raise SomeException(...)
        # ...
        if ...:
            raise SomeException(...)
        # ...
        if ...:
            raise SomeException(...)
        # ...
    except SomeException as e:
        logger.error(e.message)
        errors += 1

Upvotes: 4

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