Bindings/Python/helpers/cored_node.py

   1 # PyOpenSG is (C) Copyright 2005-2009 by Allen Bierbaum
   2 #
   3 # This file is part of PyOpenSG.
   4 #
   5 # PyOpenSG is free software; you can redistribute it and/or modify it under
   6 # the terms of the GNU Lesser General Public License as published by the Free
   7 # Software Foundation; either version 2 of the License, or (at your option)
   8 # any later version.
   9 #
  10 # PyOpenSG is distributed in the hope that it will be useful, but WITHOUT ANY
  11 # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  12 # FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
  13 # more details.
  14 #
  15 # You should have received a copy of the GNU Lesser General Public License
  16 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 import osg2
  19 import sys
  20
  21 class AllocationError(Exception):
  22    pass
  23
  24 class CoredNode(object):
  25    """ Mixin object for a Cored node type """
  26    coreType = None
  27    __slots__ = ['mNode', 'mCore']
  28
  29    def create(cls):
  30       obj = cls()
  31       obj.mNode = osg2.OSGBase.Node.create()
  32       obj.mCore = cls.coreType.create()
  33       obj.mNode.setCore(obj.mCore)
  34       return obj
  35    create = classmethod(create)
  36
  37    def __new__(cls, *args, **kwargs):
  38       # A cored not can only be created from within the cored_node module and from code named 'create'.
  39       if __name__ != sys._getframe(1).f_globals['__name__'] or \
  40          'create' != sys._getframe(1).f_code.co_name:
  41          raise AllocationError("Can't construct a '%s' directly, use %s.create()"%(cls.__name__, cls.__name__))
  42       return object.__new__(cls, *args, **kwargs)
  43
  44    def __init__(self):
  45       self.mNode = None
  46       self.mCore = None
  47
  48    def core(self):
  49       assert self.mNode.getCore() == self.mCore
  50       return self.mCore
  51
  52    def node(self):
  53       return self.mNode
  54
  55    def __getattr__(self, name):
  56       return getattr(self.mCore, name)
  57
  58    # Use code to find the calling frame.
  59    def __setattr__(self, name, value):
  60       # Figure out the module that we were called from. If it is not
  61       # the current module, then throw an exception.
  62       if __name__ != sys._getframe(1).f_globals['__name__']:
  63          raise AttributeError("Can't set attributes on a %s."%self.__class__.__name__)
  64       object.__setattr__(self, name, value)
  65
  66    def setCore(self, newCore):
  67       self.mCore = newCore
  68       self.mNode.setCore(newCore)
  69
  70 def addNodeCoreTypes(globalDict, osg2Module):
  71
  72    node_cores = []
  73
  74    node_cores.extend([(n,c) for (n,c) in osg2Module.__dict__.iteritems() if isinstance(c,type) \
  75                      and (osg2.OSGBase.NodeCore in c.__mro__) and not c.__name__.endswith("Base")])
  76
  77    for (name,ctype) in node_cores:
  78       cored_node_classname = "%sNode"%name
  79       cored_node_class = type(cored_node_classname, (CoredNode,), {'coreType':ctype,})
  80
  81       globalDict[cored_node_classname] = cored_node_class