Backport the enum package from the abortive Mailman 3 branch. This lets us

use much nicer identifiers for constants than plain ints or strings.  New code
using enumerating constants should use subclasses of enum.Enum.

Along those lines, the passwords.py module has been rewritten to use enum
constants instead of strings.  So now e.g. the default password scheme is
Mailman.passwords.Schemes.ssha and there are Scheme.pbkdf2 and Scheme.sha
(etc) schemes as well.

Also, rework the passwords.py implementation to better support unicode
passwords.  This elaborates on Tokio's r8160 by recognizing that the hash
algorithms always operate on byte-strings not on unicodes.  Thus if the secret
or response are unicodes, encode them to byte-strings via utf-8 before hashing
and comparing.

Unit tests added for both enums and passwords.

1 files changed, 132 insertions, 0 deletions

diff --git a/Mailman/enum.py b/Mailman/enum.py
new file mode 100644
index 000000000..fc05ff5b1
--- /dev/null
+++ b/Mailman/enum.py
@@ -0,0 +1,132 @@
+# Copyright (C) 2004-2007 by the Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+# USA.
+
+"""Enumeration meta class.
+
+To define your own enumeration, do something like:
+
+>>> class Colors(Enum):
+...     red = 1
+...     green = 2
+...     blue = 3
+
+Enum subclasses cannot be instantiated, but you can convert them to integers
+and from integers.  Returned enumeration attributes are singletons and can be
+compared by identity only.
+"""
+
+COMMASPACE = ', '
+
+# Based on example by Jeremy Hylton
+# Modified and extended by Barry Warsaw
+
+
+
+class EnumMetaclass(type):
+    def __init__(cls, name, bases, dict):
+        # cls == the class being defined
+        # name == the name of the class
+        # bases == the class's bases
+        # dict == the class attributes
+        super(EnumMetaclass, cls).__init__(name, bases, dict)
+        # Store EnumValues here for easy access.
+        cls._enums = {}
+        # Figure out the set of enum values on the base classes, to ensure
+        # that we don't get any duplicate values (which would screw up
+        # conversion from integer).
+        for basecls in cls.__mro__:
+            if hasattr(basecls, '_enums'):
+                cls._enums.update(basecls._enums)
+        # For each class attribute, create an EnumValue and store that back on
+        # the class instead of the int.  Skip Python reserved names.  Also add
+        # a mapping from the integer to the instance so we can return the same
+        # object on conversion.
+        for attr in dict:
+            if not (attr.startswith('__') and attr.endswith('__')):
+                intval  = dict[attr]
+                enumval = EnumValue(name, intval, attr)
+                if intval in cls._enums:
+                    raise TypeError('Multiple enum values: %s' % enumval)
+                # Store as an attribute on the class, and save the attr name
+                setattr(cls, attr, enumval)
+                cls._enums[intval] = attr
+
+    def __getattr__(cls, name):
+        if name == '__members__':
+            return cls._enums.values()
+        raise AttributeError(name)
+
+    def __repr__(cls):
+        enums = ['%s: %d' % (cls._enums[k], k) for k in sorted(cls._enums)]
+        return '<%s {%s}>' % (cls.__name__, COMMASPACE.join(enums))
+
+    def __iter__(cls):
+        for i in sorted(self._enums):
+            yield self._enums[i]
+
+    def __getitem__(cls, i):
+        # i can be an integer or a string
+        attr = cls._enums.get(i)
+        if attr is None:
+            # It wasn't an integer -- try attribute name
+            try:
+                return getattr(cls, i)
+            except (AttributeError, TypeError):
+                raise ValueError(i)
+        return getattr(cls, attr)
+
+    # Support both MyEnum[i] and MyEnum(i)
+    __call__ = __getitem__
+
+
+
+class EnumValue(object):
+    """Class to represent an enumeration value.
+
+    EnumValue('Color', 'red', 12) prints as 'Color.red' and can be converted
+    to the integer 12.
+    """
+    def __init__(self, classname, value, enumname):
+        self._classname = classname
+        self._value     = value
+        self._enumname  = enumname
+
+    def __repr__(self):
+        return 'EnumValue(%s, %s, %d)' % (
+            self._classname, self._enumname, self._value)
+
+    def __str__(self):
+        return self._enumname
+
+    def __int__(self):
+        return self._value
+
+    # Support only comparison by identity.  Yes, really raise
+    # NotImplementedError instead of returning NotImplemented.
+    def __eq__(self, other):
+        raise NotImplementedError
+
+    __ne__ = __eq__
+    __lt__ = __eq__
+    __gt__ = __eq__
+    __le__ = __eq__
+    __ge__ = __eq__
+
+
+
+class Enum:
+    __metaclass__ = EnumMetaclass