src/panucci/services.py

   1 #!/usr/bin/env python
   2 #
   3 # This file is part of Panucci.
   4 # Copyright (c) 2008-2009 The Panucci Audiobook and Podcast Player Project
   5 #
   6 # Panucci is free software: you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation, either version 3 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # Panucci is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 # GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License
  17 # along with Panucci.  If not, see <http://www.gnu.org/licenses/>.
  18 #
  19 #  from services.py -- Core Services for gPodder
  20 #  Thomas Perl <thp@perli.net>   2007-08-24
  21 #
  22 #  2009-02-13 - nikosapi: made ObservableService more Panucci-esque
  23 #
  24
  25 from logging import getLogger
  26
  27 class ObservableService(object):
  28     def __init__(self, signal_names=[], log=None):
  29         self.__log = getLogger('ObservableService') if log is None else log
  30
  31         self.observers = {}
  32         for signal in signal_names:
  33             self.observers[signal] = []
  34
  35         if not signal_names:
  36             self.__log.warning('No signal names defined...')
  37
  38     def register(self, signal_name, observer):
  39         if signal_name in self.observers:
  40             if not observer in self.observers[signal_name]:
  41                 self.observers[signal_name].append(observer)
  42                 self.__log.debug( 'Registered "%s" as an observer for "%s"',
  43                     observer.__name__, signal_name )
  44             else:
  45                 self.__log.warning(
  46                     'Observer "%s" is already added to signal "%s"',
  47                     observer.__name__, signal_name )
  48         else:
  49             self.__log.warning(
  50                 'Signal "%s" is not available for registration', signal_name )
  51
  52     def unregister(self, signal_name, observer):
  53         if signal_name in self.observers:
  54             if observer in self.observers[signal_name]:
  55                 self.observers[signal_name].remove(observer)
  56                 self.__log.debug( 'Unregistered "%s" as an observer for "%s"',
  57                     observer.__name__, signal_name )
  58             else:
  59                 self.__log.warning(
  60                     'Observer "%s" could not be removed from signal "%s"',
  61                     observer.__name__, signal_name )
  62         else:
  63             self.__log.warning(
  64                 'Signal "%s" is not available for un-registration.',
  65                 signal_name )
  66
  67     def notify(self, signal_name, *args, **kwargs):
  68         caller = kwargs.get('caller')
  69         caller = 'UnknownCaller' if caller is None else caller.__name__
  70
  71         if signal_name in self.observers:
  72             self.__log.debug(
  73                 'Sending signal "%s" for caller "%s"', signal_name, caller )
  74
  75             for observer in self.observers[signal_name]:
  76                 observer( *args )
  77         else:
  78             self.__log.warning(
  79                 'Signal "%s" (from caller "%s") is not available '
  80                 'for notification', signal_name, caller )
  81