Implementing an optional logger in code

Question

I'd like to implement an optional logger in a function. Something like:

def foo(arg1, arg2, arg3, logger=None):
    logger = logger or (lambda *x: None)

    ...
    self.logger.debug("The connection is lost.")

I want the logging to happen in case a logger exists. Otherwise, the logger's debugging won't do a thing.

Basically the easy way to achieve it is to nest every debug statement in an if logger block, but it seems messy when there are many debug statements.

Answer 1

Few options:

Create a dummy logger (my favorite):

logger = logger or logging.getLogger('dummy') #  without configuring dummy before.

Create a dummy object with one level null effect:

class DummyObject(object):
    def __getattr__(self, name):
        return lambda *x: None

logger = logger or DummyObject()

Nesting every debug statement in a block:

if logger:
    logger.debug("abc")