game/util/weakmethod.py

   1 # ###################################################
   2 # Copyright (C) 2008 The OpenAnno Team
   3 # team@openanno.org
   4 # This file is part of OpenAnno.
   5 #
   6 # OpenAnno 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 2 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # This program 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 this program; if not, write to the
  18 # Free Software Foundation, Inc.,
  19 # 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  20 # ###################################################
  21
  22 import new
  23 import weakref
  24
  25 class WeakMethod(object):
  26         def __init__(self, function):
  27                 if not callable(function):
  28                         raise ValueError("Function parameter not callable")
  29
  30                 if isinstance(function, new.instancemethod) and function.im_self is not None:
  31                         self.function = function.im_func
  32                         self.instance = weakref.ref(function.im_self)
  33                 else:
  34                         self.function = function
  35                         self.instance = None
  36
  37         def __call__(self, *args, **kwargs):
  38                 if self.instance is None:
  39                         return self.function(*args, **kwargs)
  40                 elif self.instance() is not None:
  41                         return self.function(self.instance(), *args, **kwargs)
  42                 else:
  43                         raise ReferenceError
  44
  45         def __eq__(self, other):
  46                 return self.function == other.function and self.instance() == other.instance()
  47
  48         def __ne__(self, other):
  49                 return not self.__eq__(other)