First incomplete draft of a notifying list object.

3 files changed, 151 insertions, 3 deletions

diff --git a/src/pyexiv2.py b/src/pyexiv2.py
index 309c112..87a33c9 100644
--- a/src/pyexiv2.py
+++ b/src/pyexiv2.py
@@ -246,6 +246,54 @@ class Rational(object):
         return '%d/%d' % (self.numerator, self.denominator)
 
 
+class ListenerInterface(object):
+    # Define an interface that an object that wants to listen to changes on a
+    # notifying list should implement.
+
+    def item_changed(self, index, item):
+        raise NotImplementedError()
+
+    def item_deleted(self, index):
+        raise NotImplementedError()
+
+    # TODO: define other methods.
+
+
+class NotifyingList(list):
+
+    """
+    DOCME
+    Not asynchronous.
+    """
+
+    # file:///usr/share/doc/python2.5/html/lib/typesseq-mutable.html
+    # http://docs.python.org/reference/datamodel.html#additional-methods-for-emulation-of-sequence-types
+
+    def __init__(self, items=[]):
+        super(NotifyingList, self).__init__(items)
+        self._listeners = set()
+
+    def register_listener(self, listener):
+        self._listeners.add(listener)
+
+    def unregister_listener(self, listener):
+        self._listeners.remove(listener)
+
+    def _notify_listeners(self, method_name, *args):
+        for listener in self._listeners:
+            getattr(listener, method_name)(*args)
+
+    def __setitem__(self, index, item):
+        # FIXME: support slice arguments
+        super(NotifyingList, self).__setitem__(index, item)
+        self._notify_listeners('item_changed', index, item)
+
+    def __delitem__(self, index):
+        # FIXME: support slice arguments
+        super(NotifyingList, self).__delitem__(index)
+        self._notify_listeners('item_deleted', index)
+
+
 class MetadataTag(object):
 
     """
@@ -516,7 +564,7 @@ class IptcValueError(ValueError):
                (self.xtype, self.value)
 
 
-class IptcTag(MetadataTag):
+class IptcTag(MetadataTag, ListenerInterface):
 
     """
     An IPTC metadata tag can have several values (tags that have the repeatable
@@ -533,8 +581,8 @@ class IptcTag(MetadataTag):
         Constructor.
         """
         super(IptcTag, self).__init__(key, name, label, description, xtype, values)
-        # FIXME: make values either a tuple (immutable) or a notifying list
-        self._values = map(lambda x: IptcTag._convert_to_python(x, xtype), values)
+        self._values = NotifyingList(map(lambda x: IptcTag._convert_to_python(x, xtype), values))
+        self._values.register_listener(self)
 
     def _get_values(self):
         return self._values
@@ -548,12 +596,22 @@ class IptcTag(MetadataTag):
     def _del_values(self):
         if self.metadata is not None:
             self.metadata._delete_iptc_tag(self.key)
+        self._values.unregister_listener(self)
         del self._values
 
     # DOCME
     values = property(fget=_get_values, fset=_set_values, fdel=_del_values,
                      doc=None)
 
+    # Implement the listener interface.
+
+    def item_changed(self, index, item):
+        # An item of self._values was changed.
+        # The following is a quick, non optimal solution.
+        # FIXME: do not update the whole list, only the item that changed.
+        self._set_values(self._values)
+
+
     @staticmethod
     def _convert_to_python(value, xtype):
         """
diff --git a/unittest/TestsRunner.py b/unittest/TestsRunner.py
index d4f52dc..6021453 100755
--- a/unittest/TestsRunner.py
+++ b/unittest/TestsRunner.py
@@ -35,6 +35,7 @@ import unittest
 #from Bug183332_TestCase import Bug183332_TestCase
 #from Bug183618_TestCase import Bug183618_TestCase
 from rational import TestRational
+from notifying_list import TestNotifyingList
 from exif import TestExifTag
 from iptc import TestIptcTag
 from xmp import TestXmpTag
@@ -51,6 +52,7 @@ if __name__ == '__main__':
     #suite.addTest(unittest.defaultTestLoader.loadTestsFromTestCase(Bug183332_TestCase))
     #suite.addTest(unittest.defaultTestLoader.loadTestsFromTestCase(Bug183618_TestCase))
     suite.addTest(unittest.defaultTestLoader.loadTestsFromTestCase(TestRational))
+    suite.addTest(unittest.defaultTestLoader.loadTestsFromTestCase(TestNotifyingList))
     suite.addTest(unittest.defaultTestLoader.loadTestsFromTestCase(TestExifTag))
     suite.addTest(unittest.defaultTestLoader.loadTestsFromTestCase(TestIptcTag))
     suite.addTest(unittest.defaultTestLoader.loadTestsFromTestCase(TestXmpTag))
diff --git a/unittest/notifying_list.py b/unittest/notifying_list.py
new file mode 100644
index 0000000..05372be
--- /dev/null
+++ b/unittest/notifying_list.py
@@ -0,0 +1,88 @@
+# -*- coding: utf-8 -*-
+
+# ******************************************************************************
+#
+# Copyright (C) 2009 Olivier Tilloy <olivier@tilloy.net>
+#
+# This file is part of the pyexiv2 distribution.
+#
+# pyexiv2 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.
+#
+# pyexiv2 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 pyexiv2; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, 5th Floor, Boston, MA 02110-1301 USA.
+#
+# Author: Olivier Tilloy <olivier@tilloy.net>
+#
+# ******************************************************************************
+
+import unittest
+from pyexiv2 import ListenerInterface, NotifyingList
+import random
+
+
+class SimpleListener(ListenerInterface):
+
+    # Total number of notifications
+    notifications = 0
+    # Last notification: (method_name, *args)
+    last = None
+
+    def item_changed(self, index, item):
+        self.notifications += 1
+        self.last = ('item_changed', index, item)
+
+    def item_deleted(self, index):
+        self.notifications += 1
+        self.last = ('item_deleted', index)
+
+
+class TestNotifyingList(unittest.TestCase):
+
+    def setUp(self):
+        self.values = NotifyingList([5, 7, 9, 14, 57, 3, 2])
+
+    def test_no_listener(self):
+        # No listener is registered, nothing should happen.
+        self.values[3] = 13
+        # TODO: test all operations (insertion, deletion, slicing, ...)
+
+    def test_listener_interface(self):
+        self.values.register_listener(ListenerInterface())
+        self.failUnlessRaises(NotImplementedError, self.values.__setitem__, 3, 13)
+        self.failUnlessRaises(NotImplementedError, self.values.__delitem__, 5)
+        # TODO: test all operations (insertion, slicing, ...)
+
+    def test_one_listener(self):
+        listener = SimpleListener()
+        self.values.register_listener(listener)
+        self.values[3] = 13
+        self.failUnlessEqual(listener.notifications, 1)
+        self.failUnlessEqual(listener.last, ('item_changed', 3, 13))
+        del self.values[5]
+        self.failUnlessEqual(listener.notifications, 2)
+        self.failUnlessEqual(listener.last, ('item_deleted', 5))
+        # TODO: test all operations (insertion, slicing, ...)
+
+    def test_multiple_listeners(self):
+        # Register a random number of listeners
+        listeners = [SimpleListener() for i in xrange(random.randint(3, 20))]
+        for listener in listeners:
+            self.values.register_listener(listener)
+        self.values[3] = 13
+        for listener in listeners:
+            self.failUnlessEqual(listener.notifications, 1)
+            self.failUnlessEqual(listener.last, ('item_changed', 3, 13))
+        del self.values[5]
+        for listener in listeners:
+            self.failUnlessEqual(listener.notifications, 2)
+            self.failUnlessEqual(listener.last, ('item_deleted', 5))
+        # TODO: test all operations (insertion, slicing, ...)