Wipe the widget cache at midnight

This serves two purposes:

* Relative dates and progress colors are shown correctly on the next day
* Stale cached items get wiped at least once a day (for those who continiously
  run this mode)

topydo/ui/columns/Main.py

@@ -34,6 +34,7 @@ from topydo.ui.CLIApplicationBase import CLIApplicationBase
 from topydo.ui.columns.CommandLineWidget import CommandLineWidget
 from topydo.ui.columns.ConsoleWidget import ConsoleWidget
 from topydo.ui.columns.KeystateWidget import KeystateWidget
+from topydo.ui.columns.TodoWidget import TodoWidget
 from topydo.ui.columns.TodoListWidget import TodoListWidget
 from topydo.ui.columns.Utils import PaletteItem, to_urwid_color
 from topydo.ui.columns.ViewWidget import ViewWidget
@@ -220,6 +221,7 @@ class UIApplication(CLIApplicationBase):
 
     def _set_alarm_for_next_midnight_update(self):
         def callback(p_loop, p_data):
+            TodoWidget.wipe_cache()
             self._update_all_columns()
             self._set_alarm_for_next_midnight_update()
 

topydo/ui/columns/TodoListWidget.py

@@ -106,10 +106,6 @@ class TodoListWidget(urwid.LineBox):
                 # -2 for the same reason as in self._scroll_to_bottom()
                 self.todolist.set_focus(len(self.todolist) - 2)
 
-        # after the update there might be old stuff left in the widget cache,
-        # clean it
-        TodoWidget.clean_cache(self.view.todolist)
-
     def _scroll_to_top(self, p_size):
         self.listbox.set_focus(0)
 

topydo/ui/columns/TodoWidget.py

@@ -188,19 +188,8 @@ class TodoWidget(urwid.WidgetWrap):
 
         return widget
 
-    cache_clean_counter = 0
-
     @classmethod
-    def clean_cache(p_class, p_todolist):
-        """ Cleans the widget cache once every 500 column updates. """
-
-        if p_class.cache_clean_counter % 500 != 0:
-            # wait
-            p_class.cache_clean_counter += 1
-            return
-
-        sources_in_list = set([todo.source() for todo in p_todolist])
-        sources_in_cache = set(p_class.cache.keys())
+    def wipe_cache(p_class):
+        """ Wipes the cache """
+        p_class.cache = {}
 
-        for stale in sources_in_cache - sources_in_list:
-            del p_class.cache[stale]