Implement TerminalStatus.__getitem__

2 files changed, 18 insertions, 1 deletions

diff --git a/ttystatus/status.py b/ttystatus/status.py
index b51c5c5..6eeb55e 100644
--- a/ttystatus/status.py
+++ b/ttystatus/status.py
@@ -16,7 +16,16 @@
 
 class TerminalStatus(object):
 
-    '''Show status and progress information on a terminal.'''
+    '''Show status and progress information on a terminal.
+    
+    All output is provided via widgets of various kinds. Many widgets
+    format data that TerminalStatus stores. TerminalStatus provides a
+    dict interface for setting and retrieving data items. Unlike a real
+    dict, getting a value for a key that has not been set does not
+    result in a KeyError exception, but in the empty string being
+    returned.
+    
+    '''
     
     def __init__(self):
         self.clear()
@@ -28,3 +37,8 @@ class TerminalStatus(object):
     def clear(self):
         '''Remove all widgets.'''
         self._widgets = []
+        self._values = dict()
+        
+    def __getitem__(self, key):
+        '''Return value for key, or the empty string.'''
+        return self._values.get(key, '')
diff --git a/ttystatus/status_tests.py b/ttystatus/status_tests.py
index 15a95c1..35a1463 100644
--- a/ttystatus/status_tests.py
+++ b/ttystatus/status_tests.py
@@ -36,3 +36,6 @@ class TerminalStatusTests(unittest.TestCase):
         self.ts.add(ttystatus.Literal('foo'))
         self.ts.clear()
         self.assertEqual(self.ts._widgets, [])
+        
+    def test_returns_empty_string_for_unknown_value(self):
+        self.assertEqual(self.ts['foo'], '')