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diff --git a/sharedstate.git/sharedstate/shareddict.py b/sharedstate.git/sharedstate/shareddict.py
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+# shareddict.py, classes to aid activities in sharing a state
+# Reinier Heeres, reinier@heeres.eu
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#
+# Change log:
+#   2007-06-21: rwh, first version
+
+import logging
+_logger = logging.getLogger('sharinghelper')
+
+from sharedobject import SharedObject
+
+class SharedDict(SharedObject):
+    """Shared dictionary object, generates key-based difference objects"""
+
+    def __init__(self, name, helper, opt={}):
+        SharedObject.__init__(self, name, helper, opt=opt)
+        self._value = {}
+
+    def __getitem__(self, key):
+#        _logger.debug('SharedDict.__getitem__(%s)', key)
+        return self.get_key(key)
+
+    def __setitem__(self, key, val):
+#        _logger.debug('SharedDict.__setitem__(%s, %s)', key, val)
+        return self.set_key(key, val)
+
+    def __delitem__(self, key):
+        self.delete_key(key)
+
+    def get_key(self, key, val):
+        return self._value[key]
+
+    def set_key(self, key, val):
+        if key in self._value:
+            d = {'change': {key: val}}
+        else:
+            d = {'add': {key: val}}
+        self._value[key] = val
+        self.changed(d, True)
+
+    def delete_key(self, key):
+        if key in self._value:
+            del self._value[key]
+            d = {'remove': key}
+            self.changed(d, True)
+
+    def _compatible_diffs(self, diffa, diffb):
+        for key in diffa:
+            if key in diffb:
+                return False
+        return True
+
+    def diff(self, cur, old):
+        ret = {'remove': [], 'add': {}, 'change': {}}
+        if old is None:
+            return ret
+
+        for key in set(old.keys()).difference(cur.keys()):
+            ret['remove'].append(key)
+
+        for key in set(cur.keys()).difference(old.keys()):
+            ret['add'][key] = cur[key]
+
+        for key in set(cur.keys()).intersection(old.keys()):
+            if cur[key] is not old[key]:
+                ret['change'][key] = cur[key]
+
+        return ret
+
+    def _apply_diff_to(self, obj, diffobj):
+        """Apply a diff and return an object that describes the inverse diff"""
+
+        if diffobj is None:
+            return (None, None)
+
+        ret = {'add':{}, 'remove':[], 'change':{}}
+
+        if 'remove' in diffobj:
+            for key in diffobj['remove']:
+                ret['add'][key] = obj[key]
+                del self._value[key]
+
+        if 'add' in diffobj:
+            for key, val in diffobj['add'].iteritems():
+                ret['remove'].append(key)
+                obj[key] = val
+
+        if 'change' in diffobj:
+            for key, val in diffobj['change'].iteritems():
+                ret[key] = self._value[key]
+                obj[key] = val
+
+        return (obj, ret)