src/panucci/services.py

   1 #!/usr/bin/env python
   2 #
   3 #  from services.py -- Core Services for gPodder
   4 #  Thomas Perl <thp@perli.net>   2007-08-24
   5 #
   6 #  2009-02-13 - nikosapi: made ObservableService more Panucci-esque
   7 #
   8
   9 from logging import getLogger
  10
  11 class ObservableService(object):
  12     def __init__(self, signal_names=[], log=None):
  13         self.__log = getLogger('ObservableService') if log is None else log
  14
  15         self.observers = {}
  16         for signal in signal_names:
  17             self.observers[signal] = []
  18
  19         if not signal_names:
  20             self.__log.warning('No signal names defined...')
  21
  22     def register(self, signal_name, observer):
  23         if signal_name in self.observers:
  24             if not observer in self.observers[signal_name]:
  25                 self.observers[signal_name].append(observer)
  26                 self.__log.debug( 'Registered "%s" as an observer for "%s"',
  27                     observer.__name__, signal_name )
  28             else:
  29                 self.__log.warning(
  30                     'Observer "%s" is already added to signal "%s"',
  31                     observer.__name__, signal_name )
  32         else:
  33             self.__log.warning(
  34                 'Signal "%s" is not available for registration', signal_name )
  35
  36     def unregister(self, signal_name, observer):
  37         if signal_name in self.observers:
  38             if observer in self.observers[signal_name]:
  39                 self.observers[signal_name].remove(observer)
  40                 self.__log.debug( 'Unregistered "%s" as an observer for "%s"',
  41                     observer.__name__, signal_name )
  42             else:
  43                 self.__log.warning(
  44                     'Observer "%s" could not be removed from signal "%s"',
  45                     observer.__name__, signal_name )
  46         else:
  47             self.__log.warning(
  48                 'Signal "%s" is not available for un-registration.',
  49                 signal_name )
  50
  51     def notify(self, signal_name, *args, **kwargs):
  52         caller = kwargs.get('caller')
  53         caller = 'UnknownCaller' if caller is None else caller.__name__
  54
  55         if signal_name in self.observers:
  56             self.__log.debug(
  57                 'Sending signal "%s" for caller "%s"', signal_name, caller )
  58
  59             for observer in self.observers[signal_name]:
  60                 observer( *args )
  61         else:
  62             self.__log.warning(
  63                 'Signal "%s" (from caller "%s") is not available '
  64                 'for notification', signal_name, caller )
  65