Make separate command for dependencies.

Command.py

@@ -6,3 +6,15 @@ class Command(object):
     def execute(self):
         """ The command to execute. """
         return False
+
+    def argument(self, p_number):
+        """ Retrieves a value from the argument list. """
+        try:
+            value = self.args[p_number]
+        except IndexError:
+            self.usage()
+
+        return value
+
+    def usage(self):
+        return ""

DepCommand.py

+import Command
+import Config
+import Sorter
+from Utils import convert_todo_number
+import View
+
+class DepCommand(Command.Command):
+    def __init__(self, p_args, p_todolist):
+        super(DepCommand, self).__init__(p_args, p_todolist)
+        self.subsubcommand = self.argument(0)
+
+    def _handle_add(self):
+        (from_todo, to_todo) = self._get_todo_numbers()
+        self.todolist.add_dependency(from_todo, to_todo)
+
+    def _handle_rm(self):
+        (from_todo, to_todo) = self._get_todo_numbers()
+        self.todolist.remove_dependency(from_todo, to_todo)
+
+    def _get_todo_numbers(self):
+        from_todonumber = convert_todo_number(self.argument(1))
+        to_todonumber = self.argument(2)
+
+        if to_todonumber == 'to':
+            to_todonumber = convert_todo_number(self.argument(3))
+        else:
+            to_todonumber = convert_todo_number(to_todonumber)
+
+        return (from_todonumber, to_todonumber)
+
+    def _handle_ls(self):
+        """ Handles the ls subsubcommand. """
+        arg1 = self.argument(1)
+        arg2 = self.argument(2)
+
+        todos = []
+        if arg2 == 'to':
+            # dep ls 1 to ...
+            todos = self.todolist.children(convert_todo_number(arg1))
+        elif arg1 == 'to':
+            # dep ls ... to 1
+            todos = self.todolist.parents(convert_todo_number(arg2))
+        else:
+            self.usage()
+
+        if todos:
+            sorter = Sorter.Sorter(Config.SORT_STRING)
+            view = View.View(sorter, [], todos)
+            print view.pretty_print() # FIXME
+
+    def execute(self):
+        dispatch = {
+            'add':   self._handle_add,
+            'rm':    self._handle_rm,
+            'del':   self._handle_rm,
+            'ls':    self._handle_ls,
+            'clean': self.todolist.clean_dependencies,
+            'gc':    self.todolist.clean_dependencies,
+        }
+
+        dispatch[self.subsubcommand]() if self.subsubcommand in dispatch \
+            else self.usage()
+
+        return True

Main.py

@@ -5,6 +5,7 @@ import re
 import sys
 
 from AddCommand import AddCommand
+from DepCommand import DepCommand
 import Config
 import Filter
 from PrettyPrinter import pretty_print
@@ -13,7 +14,6 @@ import Sorter
 import TodoFile
 import TodoList
 from Utils import convert_todo_number
-import View
 
 def print_iterable(p_iter):
     """ Prints an iterable to the standard output, one item per line. """
@@ -77,53 +77,8 @@ class Application(object): # TODO: rename to CLIApplication
         self.print_todo(number)
 
     def dep(self):
-        """ Handles dependencies between todos. """
-        def handle_add_rm(operation):
-            """ Handles the add and rm subsubcommands. """
-            from_todonumber = convert_todo_number(argument(3))
-            to_todonumber = argument(4)
-
-            if to_todonumber == 'to':
-                to_todonumber = convert_todo_number(argument(5))
-            else:
-                to_todonumber = convert_todo_number(to_todonumber)
-
-            if operation == 'add':
-                self.todolist.add_dependency(from_todonumber, to_todonumber)
-            else:
-                self.todolist.remove_dependency(from_todonumber, to_todonumber)
-
-        def handle_ls():
-            """ Handles the ls subsubcommand. """
-            arg1 = argument(3)
-            arg2 = argument(4)
-
-            todos = []
-            if arg2 == 'to':
-                # dep ls 1 to ...
-                todos = self.todolist.children(convert_todo_number(arg1))
-            elif arg1 == 'to':
-                # dep ls ... to 1
-                todos = self.todolist.parents(convert_todo_number(arg2))
-            else:
-                usage()
-
-            if todos:
-                sorter = Sorter.Sorter(Config.SORT_STRING)
-                view = View.View(sorter, [], todos)
-                print view.pretty_print()
-
-        subsubcommand = argument(2)
-        if subsubcommand == 'add' or \
-            subsubcommand == 'rm' or subsubcommand == 'del':
-
-            handle_add_rm(subsubcommand)
-        elif subsubcommand == 'clean' or subsubcommand == 'gc':
-            self.todolist.clean_dependencies()
-        elif subsubcommand == 'ls':
-            handle_ls()
-        else:
-            usage()
+        command = DepCommand(arguments(), self.todolist)
+        command.execute()
 
     def do(self):
         def complete_children(p_number):