Add convenience function to check priority validity.

PriorityCommand.py

-import re
-
 import Command
-from Utils import convert_todo_number
+from Utils import convert_todo_number, is_valid_priority
 
 class PriorityCommand(Command.Command):
     def __init__(self, p_args, p_todolist):
@@ -11,7 +9,7 @@ class PriorityCommand(Command.Command):
         self.priority = self.argument(1)
 
     def execute(self):
-        if re.match('^[A-Z]$', self.priority):
+        if is_valid_priority(self.priority):
             old_priority = self.todo.priority()
             self.todolist.set_priority(self.number, self.priority)
 

TodoBase.py

@@ -6,6 +6,7 @@ from datetime import date
 import re
 
 import TodoParser
+from Utils import is_valid_priority
 
 class TodoBase(object):
     """
@@ -116,7 +117,7 @@ class TodoBase(object):
         """
 
         if not self.is_completed() and \
-            (p_priority == None or re.match('^[A-Z]$', p_priority)):
+            (p_priority == None or is_valid_priority(p_priority)):
 
             self.fields['priority'] = p_priority
 

Utils.py

@@ -35,3 +35,5 @@ def convert_todo_number(p_number):
 
     return p_number
 
+def is_valid_priority(p_priority):
+    return re.match(r'^[A-Z]$', p_priority) != None