add add_deprecated_argument

letsencrypt/le_util.py

@@ -1,4 +1,5 @@
 """Utilities for all Let's Encrypt."""
+import argparse
 import collections
 import errno
 import logging
@@ -255,3 +256,23 @@ def safe_email(email):
     else:
         logger.warn("Invalid email address: %s.", email)
         return False
+
+
+def add_deprecated_argument(add_argument, argument_name):
+    """Adds a deprecated argument with the name argument_name.
+
+    Deprecated arguments are not shown in the help. If they are used on
+    the command line, a warning is shown stating that the argument is
+    deprecated and no other action is taken.
+
+    :param callable add_argument: Function that adds arguments to an
+        argument parser/group.
+    :param str argument_name: Name of deprecated argument.
+
+    """
+    class ShowWarning(argparse.Action):
+        """Action to log a warning when an argument is used."""
+        def __call__(self, unused1, unused2, unused3, option_string=None):
+            print "Use of {0} is deprecated".format(option_string)
+
+    add_argument(argument_name, action=ShowWarning, help=argparse.SUPPRESS)