[core/theme] Improve items that are lists

Until now, using a list as prefix/suffix didn't work as expected,
because the corresponding method for retrieving the value was called
multiple times, and each time, the next icon would be retrieved.

Changed the logic inside the theme to only update the indices every time
that an actual update was happening.

core/theme.py

@@ -34,6 +34,7 @@ class Theme(object):
         self.__previous = {}
         self.__current = {}
         self.__keywords = {}
+        self.__value_idx = {}
         self.__data = raw_data if raw_data else self.load(name)
         for icons in self.__data.get('icons', []):
             util.algorithm.merge(self.__data, self.load(icons, 'icons'))
@@ -81,6 +82,9 @@ class Theme(object):
         self.__current.clear()
         self.__previous.clear()
 
+        for key, value in self.__value_idx.items():
+            self.__value_idx[key] = value + 1
+
     def __next_widget(self):
         self.__widget_count = self.__widget_count + 1
         self.__previous = dict(self.__current)
@@ -119,9 +123,9 @@ class Theme(object):
             value = self.__keywords.get(value, value)
 
         if isinstance(value, list):
-            key = '__{}-idx__'.format(key)
-            idx = widget.get(key, 0)
-            widget.set(key, (idx + 1) % len(value))
+            idx = self.__value_idx.get('{}::{}'.format(widget.id, key), 0) % len(value)
+            self.__value_idx['{}::{}'.format(widget.id, key)] = idx
+            widget.set(key, idx)
             value = value[idx]
         self.__current[key] = value
         return value

tests/core/test_theme.py

@@ -108,6 +108,8 @@ class theme(unittest.TestCase):
 
         for i in range(0, len(expected)*3):
             self.assertEqual(expected[i%len(expected)], theme.get('fg', widget))
+            self.assertEqual(expected[i%len(expected)], theme.get('fg', widget)) # ensure multiple invocations are OK
+            core.event.trigger('update')
 
     def test_state(self):
         widget = core.widget.Widget()