Got rid of some invalid super() calls in EditCommand.

* Moved one super() call outside the EditCommand class into a lambda
  function.
* Made EditCommand.execute() call its correct parent execute() (was:
  ListCommand). However, this would go wrong:

  EditCommand.execute() calls MultiCommand.execute()
  MultiCommand.execute() calls ListCommand.execute()
      Because EditCommand has multiple inheritance
  ListCommand.execute() is successful, but returns None
  MultiCommand.execute() takes that as failure, returns False
  EditCommand.execute() returns False

  This is fixed by adding return True to the execute() method of the
  parent classes.

This fixes all pylint errors.

topydo/lib/EditCommand.py

@@ -26,6 +26,10 @@ from topydo.lib.TodoListBase import InvalidTodoException
 from topydo.lib.TodoList import TodoList
 from topydo.lib.PrettyPrinterFilter import PrettyPrinterNumbers
 
+# Access the base class of the TodoList instance kept inside EditCommand. We
+# cannot use super() inside the class itself
+BASE_TODOLIST = lambda tl: super(TodoList, tl)
+
 class EditCommand(MultiCommand, ListCommand):
     def __init__(self, p_args, p_todolist, p_output, p_error, p_input):
         super(EditCommand, self).__init__(p_args, p_todolist, p_output,
@@ -87,7 +91,7 @@ class EditCommand(MultiCommand, ListCommand):
             return None
 
     def execute(self):
-        if not super(ListCommand, self).execute():
+        if not super(EditCommand, self).execute():
             return False
 
         self.printer.add_filter(PrettyPrinterNumbers(self.todolist))
@@ -123,7 +127,7 @@ class EditCommand(MultiCommand, ListCommand):
                         new_todos = self._todos_from_temp(temp_todos)
                         if len(new_todos) == len(self.todos):
                             for todo in self.todos:
-                                super(TodoList, self.todolist).delete(todo)
+                                BASE_TODOLIST(self.todolist).delete(todo)
 
                             for todo in new_todos:
                                 self.todolist.add_todo(todo)

topydo/lib/ListCommand.py

@@ -102,6 +102,8 @@ class ListCommand(Command):
         self._process_flags()
         self._print()
 
+        return True
+
     def usage(self):
         return """Synopsis: ls [-x] [-s <sort_expression>] [expression]"""
 

topydo/lib/MultiCommand.py

@@ -81,3 +81,5 @@ class MultiCommand(Command):
         else:
             for error in todo_errors:
                 self.error(error)
+
+        return True