1 # Copyright (c) 2014 The Chromium OS Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 import logging 6 7 8 def log(method_to_log): 9 """ A decorator method to log when 'decorated' methods have been executed. 10 This greatly simplifies tracing of the method calls. 11 12 To log execution of a method just decorate it with *log 13 14 The decorator logs the method to be executed, its class, the arguments 15 supplied to it and its return value. 16 17 @param method_to_log: Method object that will be logged and invoked. 18 19 """ 20 def log_wrapper(self, *args, **kwargs): 21 """ Actual method doing the logging and also invokes method_to_log 22 """ 23 24 log_str = '%s.%s' % (self.__class__.__name__, method_to_log.__name__) 25 26 logging.debug('+ ' + log_str) 27 28 have_args = len(args) > 0 29 have_kwargs = len(kwargs) > 0 30 31 if have_args: 32 logging.debug('*** Begin arguments:') 33 logging.debug(args) 34 logging.debug('=== End arguments.') 35 36 if have_kwargs: 37 logging.debug('*** Begin keyword arguments:') 38 logging.debug(kwargs) 39 logging.debug('=== End keyword arguments.') 40 41 result = method_to_log(self, *args, **kwargs) 42 43 if result is not None: 44 logging.debug('### Begin results :') 45 logging.debug(result) 46 logging.debug('--- End results.') 47 48 logging.debug('- ' + log_str) 49 50 return result 51 52 return log_wrapper
