Remove ANSI codes when not connected to a TTY.

Main.py

@@ -16,6 +16,7 @@ from PrettyPrinter import *
 from PriorityCommand import PriorityCommand
 import TodoFile
 import TodoList
+from Utils import escape_ansi
 
 def usage():
     """ Prints the usage of the todo.txt CLI """
@@ -36,6 +37,17 @@ def arguments(p_start=2):
 
     return values
 
+def write(p_file, p_string):
+    """
+    Write p_string to file p_file, trailed by a newline character.
+
+    ANSI codes are removed when the file is not a TTY.
+    """
+    if not p_file.isatty():
+        p_string = escape_ansi(p_string)
+
+    p_file.write(p_string + "\n")
+
 class CLIApplication(object):
     def __init__(self):
         self.todolist = TodoList.TodoList([])
@@ -57,7 +69,6 @@ class CLIApplication(object):
             if archive.is_dirty():
                 archive_file.write(str(archive))
 
-
     def run(self):
         """ Main entry function. """
         todofile = TodoFile.TodoFile(Config.FILENAME)
@@ -92,8 +103,8 @@ class CLIApplication(object):
             args = arguments(1)
 
         command = subcommand_map[subcommand](args, self.todolist,
-            lambda o: sys.stdout.write(o + "\n"),
-            lambda e: sys.stderr.write(e + "\n"),
+            lambda o: write(sys.stdout, o + "\n"),
+            lambda e: write(sys.stderr, e + "\n"),
             raw_input)
 
         if command.execute() == False:

Utils.py

@@ -40,3 +40,8 @@ def convert_todo_number(p_number):
 
 def is_valid_priority(p_priority):
     return p_priority != None and re.match(r'^[A-Z]$', p_priority) != None
+
+def escape_ansi(p_string):
+    return escape_ansi.pattern.sub('', p_string)
+
+escape_ansi.pattern = re.compile(r'\x1b[^m]*m')

test/CommandTest.py

 import unittest
 
+from Utils import escape_ansi
+
 class CommandTest(unittest.TestCase):
     def __init__(self, *args, **kwargs):
         super(CommandTest, self).__init__(*args, **kwargs)
@@ -7,7 +9,7 @@ class CommandTest(unittest.TestCase):
         self.errors = ""
 
     def out(self, p_output):
-        self.output += p_output + "\n";
+        self.output += escape_ansi(p_output + "\n")
 
     def error(self, p_error):
-        self.errors += p_error + "\n";
+        self.errors += escape_ansi(p_error + "\n")