A4 portrait - PET: Python Entre Todos - Python Argentina

Decorator classes with arguments 32
)
logging.debug("; ".join(message))
In a decorator class that doesn’t receive parameters, the first param of __init__
method is the callable to be decorated. The __call__ method receives the arguments
of the decorated callable.
The most interesting difference with the function version is that by using a class
decorator we have avoided the need of a nested function.
The way to use this decorator is the same as we do with decorator functions:
@LogCallable
def yes(string='y', end='\n'):
[...]
Decorator classes with arguments
Understanding the 3 previous cases it is possible to guess how a decorator class with
arguments should be.
LogCallable with params example:
class LogCallable(object):
"""Decorates callable and logs information about it.
Logs how many times the callable was called and the params it had.
"""
def __init__(self, do_count):
self.do_count = do_count
if not getattr(LogCallable, 'count_dict', None) and do_count:
LogCallable.count_dict = {}
def __call__(self, callable):
def wrap(*args, **kwargs):
callable(*args, **kwargs)
message = []
if self.do_count:
LogCallable.count_dict.setdefault(
callable.__name__, 0
)
LogCallable.count_dict[callable.__name__] += 1
message.append(
u"""called: '{0}' '{1} times'""".format(
callable.__name__,
LogCallable.count_dict[callable.__name__],
)
)
else:
message.append(u"""called: '{0}'""".format(callable.__name__))
message.append(
u"""Arguments: {0}""".format(
", ".join(map(str, args))
)
)
message.append(
u"""Keyword Arguments: {0}""".format(
PET: English Translation (Issue 1, August 2010) — http://revista.python.org.ar