Fix for: 1277: database corroption on delete outside of DisplayTabs while tab open

Introduces the concept of callman.py as one single way to follow handles an
interface is interested in. 
dbguielement.py contains a small base class using that, usable for all windows/
guielements that need to track database changes to handles


svn: r12881

src/gui/Makefile.am

@@ -10,6 +10,7 @@ pkgdatadir = $(datadir)/@PACKAGE@/gui
 
 pkgdata_PYTHON = \
 	__init__.py \
+	dbguielement.py \
 	dbloader.py \
 	dbman.py \
 	grampsgui.py \

src/gui/dbguielement.py

@@ -0,0 +1,89 @@
+#
+# Gramps - a GTK+/GNOME based genealogy program
+#
+# Copyright (C) 2009       Benny Malengier
+#
+# 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+# $Id$
+
+"""
+Group common stuff GRAMPS GUI elements must be able to do when tracking a DB:
+   * connect to db signals
+   * listen to db changes to update themself on relevant changes
+   * determine if the GUI has become out of sync with the db
+"""
+
+#-------------------------------------------------------------------------
+#
+# GRAMPS modules
+#
+#-------------------------------------------------------------------------
+from gen.utils.callman import CallbackManager
+
+#-------------------------------------------------------------------------
+#
+# GUIElement class
+#
+#-------------------------------------------------------------------------
+class DbGUIElement(object):
+    """
+    Group common stuff GRAMPS GUI elements must be able to do when tracking 
+    a DB:
+        * connect to db signals
+        * listen to db changes to update themself on relevant changes
+        * determine if the GUI has become out of sync with the db
+    Most interaction with the DB should be done via the callman attribute.
+    On initialization, the method _connect_db_signals is called. Inheriting 
+    objects are advised to group the setup of the callman attribute here.
+    
+    .. attribute callman : a `~gen.utils.callman.CallbackManager` object, to 
+            be used to track specific changes in the db and set up callbacks
+    """
+    def __init__(self, database):
+        self.callman = CallbackManager(database)
+        self._connect_db_signals()
+    
+    def _add_db_signal(self, name, callback):
+        """
+        Convenience function to add a custom db signal. The attributes are just
+        passed to the callman object. 
+        For primary objects, use the register method of the callman attribute.
+        
+        :param name: name of the signal to connect to
+        :type name: string
+        :param callback: function to call when signal is emitted
+        :type callback: a funtion or method with the correct signature for the
+                signal
+        """
+        self.callman.add_db_signal(name, callback)
+    
+    def _connect_db_signals(self):
+        """
+        Convenience method that is called on initialization of DbGUIElement. 
+        Use this to group setup of the callman attribute
+        """
+        pass
+    
+    def _cleanup_callbacks(self):
+        """
+        Remove all db callbacks. 
+        This is done automatically on destruction of the object, but is
+        normally needed earlier, calling this method does so.
+        """
+        database = self.callman.database
+        self.callman.disconnect_all()
+        self.callman = CallbackManager(database)