Add %P to `ls` format options.

%P will display the priority if one is given, or print a 'placeholder' space
if none is present.

test/test_list_format.py

@@ -119,6 +119,8 @@ class ListFormatTest(CommandTest):
 |  6| x 2014-12-12 Completed but with                           date:2014-12-12
 """
 
+        self.assertEqual(self.output, result)
+
     @mock.patch('topydo.lib.ListFormat.get_terminal_size')
     def test_list_format06(self, mock_terminal_size):
         mock_terminal_size.return_value = self.terminal_size(100, 25)
@@ -648,5 +650,32 @@ Z   Z
 """
         self.assertEqual(self.output, result)
 
+    def test_list_format43(self):
+        command = ListCommand(["-x", "-F", "%P -"], self.todolist, self.out, self.error)
+        command.execute()
+
+        result = """D -
+Z -
+C -
+C -
+  -
+  -
+"""
+        self.assertEqual(self.output, result)
+
+    def test_list_format44(self):
+        command = ListCommand(["-x", "-F", "%i %{(}P{)}"], self.todolist, self.out, self.error)
+        command.execute()
+
+        result = """1 (D)
+2 (Z)
+3 (C)
+4 (C)
+5 ( )
+6 ( )
+"""
+        self.assertEqual(self.output, result)
+
+
 if __name__ == '__main__':
     unittest.main()

topydo/commands/ListCommand.py

@@ -177,6 +177,7 @@ When an expression is given, only the todos matching that expression are shown.
          %k: List of tags separated by spaces (excluding hidden tags).
          %K: List of all tags separated by spaces.
          %p: Priority.
+         %P: Priority or placeholder space if no priority.
          %s: Todo text.
          %S: Todo text, truncated such that an item fits on one line.
          %t: Absolute creation date.

topydo/lib/ListFormat.py

@@ -152,6 +152,7 @@ class ListFormatParser(object):
 
             # relative dates in form:  creation, due, start
             'H': lambda t: humanize_dates(t.due_date(), t.start_date(), t.creation_date()),
+
             # todo ID
             'i': lambda t: str(self.todolist.number(t)),
 
@@ -172,6 +173,9 @@ class ListFormatParser(object):
             # priority
             'p': lambda t: t.priority() if t.priority() else '',
 
+            # priority (or placeholder space)
+            'P': lambda t: t.priority() if t.priority() else ' ',
+
             # text
             's': lambda t: t.text(),