decorators.py

import functools
import logging
import traceback
import os

def log_calls(f):
    """
    displays arguments and return val for debugging purposes
    based on:
    http://caines.ca/blog/programming/the-debuggerator-a-practical-intro-to-decorators-in-python/
    """
    @functools.wraps(f)
    def wrapped(*args, **kwargs):
        """
        
        """
        call_string = "%s called with *args: %r, **kwargs: %r " \
                        % (f.__name__, args, kwargs)
        try:
            retval = f(*args, **kwargs)
            call_string += " --> " + repr(retval)
            logging.debug(call_string)
            return retval
        except Exception, e:
            top = traceback.extract_stack()[-1]
            call_string += " RAISED EXCEPTION: "
            call_string += ", ".join([type(e).__name__, 
                                      os.path.basename(top[0]),
                                      str(top[1]),
                                      str(e)])
            logging.debug(call_string)
            raise
    return wrapped
    

    
if __name__ == '__main__':
    logging.basicConfig(level=logging.DEBUG)

    @log_calls
    def test(msg):
        msg + 1

    test('hola')