1 files changed, 74 insertions, 0 deletions
diff --git a/src/tutorius/filters.py b/src/tutorius/filters.py
new file mode 100644
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+++ b/src/tutorius/filters.py
@@ -0,0 +1,74 @@
+# Copyright (C) 2009, Tutorius.org
+# Copyright (C) 2009, Vincent Vinet <vince.vinet@gmail.com>
+#
+# 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
+
+import logging
+logger = logging.getLogger("filters")
+
+from . import properties
+
+
+class EventFilter(properties.TPropContainer):
+    """
+    Base class for an event filter
+    """
+
+    def __init__(self):
+        """
+        Constructor.
+        """
+        super(EventFilter, self).__init__()
+        self._callback = None
+
+    def install_handlers(self, callback, **kwargs):
+        """
+        install_handlers is called for eventfilters to setup all
+        necessary event handlers to be able to catch the desired
+        event. 
+
+        @param callback the callback function that will be called
+        with the event filter as an argument when the event is catched
+        and validated.
+        @param **kwargs unused by this handler for now, allows subclasses
+        to receive information about the context when installing
+
+        Subclasses must call this super method to setup the callback if they 
+        feel like cooperating
+        """
+        self._callback = callback
+
+    def remove_handlers(self):
+        """
+        remove_handlers is called when a state is done so that all
+        event filters can cleanup any handlers they have installed
+
+        This function will also clear the callback function so that any 
+        leftover handler that is triggered will not be able to change the
+        application state.
+
+        subclasses must call this super method to cleanup the callback if they
+        collaborate and use this classe's do_callback()
+        """
+        self._callback = None
+
+    def do_callback(self, *args, **kwargs):
+        """
+        Default callback function that calls the event filter callback
+        with the event filter as only argument.
+        """
+        if self._callback:
+            self._callback(self)
+