Add TerminalStatus.increase.

2 files changed, 10 insertions, 0 deletions

diff --git a/ttystatus/status.py b/ttystatus/status.py
index 3584499..5a4e0fe 100644
--- a/ttystatus/status.py
+++ b/ttystatus/status.py
@@ -52,6 +52,10 @@ class TerminalStatus(object):
             w.update(self, 999)
         self._m.write(''.join(str(w) for w in self._widgets))
     
+    def increase(self, key, delta):
+        '''Increase value for a key by a given amount.'''
+        self[key] = (self[key] or 0) + delta
+    
     def notify(self, msg):
         '''Show a message.'''
         self._m.notify(msg)
diff --git a/ttystatus/status_tests.py b/ttystatus/status_tests.py
index 5640680..5b4cada 100644
--- a/ttystatus/status_tests.py
+++ b/ttystatus/status_tests.py
@@ -65,6 +65,12 @@ class TerminalStatusTests(unittest.TestCase):
         self.assertEqual(str(w), '')
         self.ts['foo'] = 'bar'
         self.assertEqual(str(w), 'bar')
+
+    def test_increases_value(self):
+        self.ts['foo'] = 10
+        self.assertEqual(self.ts['foo'], 10)
+        self.ts.increase('foo', 10)
+        self.assertEqual(self.ts['foo'], 20)
         
     def test_has_notify_method(self):
         self.assertEqual(self.ts.notify('foo'), None)