implemented config class as far as necessary, one check is still failing

Added odict module to get an OrderedDict to be used in the config parser, assuring the order of sections and options does not change

2 files changed, 1635 insertions, 20 deletions

diff --git a/lib/git/config.py b/lib/git/config.py
index c7f2c398..0187af1d 100644
--- a/lib/git/config.py
+++ b/lib/git/config.py
@@ -9,24 +9,67 @@ configuration files
 """
 
 import re
-from ConfigParser import RawConfigParser
+import os
+import ConfigParser as cp
+from git.odict import OrderedDict
+import inspect
 
 class _MetaParserBuilder(type):
 	"""
-	Utlity class wrapping methods into decorators that assure read-only properties
+	Utlity class wrapping base-class methods into decorators that assure read-only properties
 	"""
+	def __new__(metacls, name, bases, clsdict):
+		"""
+		Equip all base-class methods with a _needs_values decorator, and all non-const methods
+		with a _set_dirty_and_flush_changes decorator in addition to that.
+		"""
+		new_type = super(_MetaParserBuilder, metacls).__new__(metacls, name, bases, clsdict)
+		
+		mutating_methods = clsdict['_mutating_methods_']
+		for base in bases:
+			methods = ( t for t in inspect.getmembers(base, inspect.ismethod) if not t[0].startswith("_") )
+			for name, method in methods:
+				if name in clsdict:
+					continue
+				method_with_values = _needs_values(method)
+				if name in mutating_methods:
+					method_with_values = _set_dirty_and_flush_changes(method_with_values)
+				# END mutating methods handling
+				clsdict[name] = method_with_values
+		# END for each base
+		
+		return new_type
+	
+	
 
 def _needs_values(func):
-	"""Returns method assuring we read values (on demand) before we try to access them"""
-	return func
+	"""
+	Returns method assuring we read values (on demand) before we try to access them
+	"""
+	def assure_data_present(self, *args, **kwargs):
+		self.read()
+		return func(self, *args, **kwargs)
+	# END wrapper method
+	assure_data_present.__name__ = func.__name__
+	return assure_data_present
 	
-def _ensure_writable(non_const_func):
-	"""Return method that checks whether given non constant function may be called.
-	If so, the instance will be set dirty"""
+def _set_dirty_and_flush_changes(non_const_func):
+	"""
+	Return method that checks whether given non constant function may be called.
+	If so, the instance will be set dirty.
+	Additionally, we flush the changes right to disk
+	"""
+	def flush_changes(self, *args, **kwargs):
+		rval = non_const_func(self, *args, **kwargs)
+		self.write()
+		return rval
+	# END wrapper method
+	flush_changes.__name__ = non_const_func.__name__
+	return flush_changes
 	
 	
 
-class GitConfigParser(RawConfigParser, object):
+class GitConfigParser(cp.RawConfigParser, object):
 	"""
 	Implements specifics required to read git style configuration files.
 	
@@ -38,6 +81,10 @@ class GitConfigParser(RawConfigParser, object):
 	
 	The configuration file will be locked if you intend to change values preventing other 
 	instances to write concurrently.
+	
+	NOTE
+		The config is case-sensitive even when queried, hence section and option names
+		must match perfectly.
 	"""
 	__metaclass__ = _MetaParserBuilder
 	
@@ -51,45 +98,214 @@ class GitConfigParser(RawConfigParser, object):
 		)
 	
 	# list of RawConfigParser methods able to change the instance
-	_mutating_methods_ = tuple()	
-	
+	_mutating_methods_ = ("remove_section", "remove_option", "set")
 	
 	def __init__(self, file_or_files, read_only=True):
 		"""
 		Initialize a configuration reader to read the given file_or_files and to 
-		possibly allow changes to it by setting read_only False 
+		possibly allow changes to it by setting read_only False
+		
+		``file_or_files``
+			A single file path or file objects or multiple of these
+		
+		``read_only``
+			If True, the ConfigParser may only read the data , but not change it.
+			If False, only a single file path or file object may be given.
 		"""
+		# initialize base with ordered dictionaries to be sure we write the same 
+		# file back 
+		self._sections = OrderedDict()
+		self._defaults = OrderedDict()
+		
 		self._file_or_files = file_or_files
 		self._read_only = read_only
+		self._owns_lock = False
 		self._is_initialized = False
-		self._is_dirty = False
+		
+		
+		if not read_only:
+			if isinstance(file_or_files, (tuple, list)):
+				raise ValueError("Write-ConfigParsers can operate on a single file only, multiple files have been passed")
+			# END single file check
+			
+			self._file_name = file_or_files
+			if not isinstance(self._file_name, basestring):
+				self._file_name = file_or_files.name
+			# END get filename
+			
+			self._obtain_lock_or_raise()	
+		# END read-only check
+		
 	
 	def __del__(self):
 		"""
 		Write pending changes if required and release locks
 		"""
+		if self.read_only:
+			return 
+		
+		try:
+			try:
+				self.write()
+			except IOError,e:
+				print "Exception during destruction of GitConfigParser: %s" % str(e)
+		finally:
+			self._release_lock()
+	
+	def _lock_file_path(self):
+		"""
+		Return
+			Path to lockfile
+		"""
+		return "%s.lock" % (self._file_name)
+	
+	def _has_lock(self):
+		"""
+		Return
+			True if we have a lock and if the lockfile still exists
+			
+		Raise
+			AssertionError if our lock-file does not exist
+		"""
+		if not self._owns_lock:
+			return False
+		
+		lock_file = self._lock_file_path()
+		try:
+			fp = open(lock_file, "r")
+			pid = int(fp.read())
+			fp.close()
+		except IOError:
+			raise AssertionError("GitConfigParser has a lock but the lock file at %s could not be read" % lock_file)
+		
+		if pid != os.getpid():
+			raise AssertionError("We claim to own the lock at %s, but it was not owned by our process: %i" % (lock_file, os.getpid()))
+		
+		return True
+		
+	def _obtain_lock_or_raise(self):
+		"""
+		Create a lock file as flag for other instances, mark our instance as lock-holder
+		
+		Raise
+			IOError if a lock was already present or a lock file could not be written
+		"""
+		if self._has_lock():
+			return 
+			
+		lock_file = self._lock_file_path()
+		if os.path.exists(lock_file):
+			raise IOError("Lock for file %r did already exist, delete %r in case the lock is illegal" % (self._file_name, lock_file))
+		
+		fp = open(lock_file, "w")
+		fp.write(str(os.getpid()))
+		fp.close()
+		
+		self._owns_lock = True
+		
+	def _release_lock(self):
+		"""
+		Release our lock if we have one
+		"""
+		if not self._has_lock():
+			return 
+			
+		os.remove(self._lock_file_path())
+		self._owns_lock = False
+		
+	def optionxform(self, optionstr):
+		"""
+		Do not transform options in any way when writing
+		"""
+		return optionstr
 	
 	def read(self):
 		"""
-		Read configuration information from our file or files
+		Reads the data stored in the files we have been initialized with
+		
+		Returns
+			Nothing
+		
+		Raises
+			IOError if not all files could be read
 		"""
 		if self._is_initialized:
-			return 
+			return
+			
+		
+		files_to_read = self._file_or_files
+		if not isinstance(files_to_read, (tuple, list)):
+			files_to_read = [ files_to_read ]
 		
+		for file_object in files_to_read:
+			fp = file_object
+			close_fp = False
+			# assume a path if it is not a file-object
+			if not hasattr(file_object, "seek"):
+				fp = open(file_object, "w")
+				close_fp = True
+			# END fp handling
+				
+			try:
+				self._read(fp, fp.name)
+			finally:
+				if close_fp:
+					fp.close()
+			# END read-handling
+		# END  for each file object to read
 		self._is_initialized = True
 		
-	@_ensure_writable
+	def _write(self, fp):
+		"""Write an .ini-format representation of the configuration state in 
+		git compatible format"""
+		def write_section(name, section_dict):
+			fp.write("[%s]\n" % name)
+			for (key, value) in section_dict.items():
+				if key != "__name__":
+					fp.write("\t%s = %s\n" % (key, str(value).replace('\n', '\n\t')))
+				# END if key is not __name__
+		# END section writing 
+		
+		if self._defaults:
+			write_section(cp.DEFAULTSECT, self._defaults)
+		map(lambda t: write_section(t[0],t[1]), self._sections.items())
+
+		
 	def write(self):
 		"""
-		Write our changes to our file
+		Write changes to our file, if there are changes at all
 		
 		Raise
-			AssertionError if this is a read-only writer instance
+			IOError if this is a read-only writer instance or if we could not obtain 
+			a file lock
 		"""
-		if not self._is_dirty:
-			return
+		self._assure_writable("write")
+		self._obtain_lock_or_raise()
+		
+		
+		fp = self._file_or_files
+		close_fp = False
+		
+		if not hasattr(fp, "seek"):
+			fp = open(self._file_or_files, "w")
+			close_fp = True
+		else:
+			fp.seek(0)
+		
+		# WRITE DATA
+		try:
+			self._write(fp)
+		finally:
+			if close_fp:
+				fp.close()
+		# END data writing
+			
+		# we do not release the lock - it will be done automatically once the 
+		# instance vanishes
 		
-		self._is_dirty = False
+	def _assure_writable(self, method_name):
+		if self.read_only:
+			raise IOError("Cannot execute non-constant method %s.%s" % (self, method_name))
 		
 	@property
 	def read_only(self):
diff --git a/lib/git/odict.py b/lib/git/odict.py
new file mode 100644
index 00000000..2c8391d7
--- /dev/null
+++ b/lib/git/odict.py
@@ -0,0 +1,1399 @@
+# odict.py
+# An Ordered Dictionary object
+# Copyright (C) 2005 Nicola Larosa, Michael Foord
+# E-mail: nico AT tekNico DOT net, fuzzyman AT voidspace DOT org DOT uk
+
+# This software is licensed under the terms of the BSD license.
+# http://www.voidspace.org.uk/python/license.shtml
+# Basically you're free to copy, modify, distribute and relicense it,
+# So long as you keep a copy of the license with it.
+
+# Documentation at http://www.voidspace.org.uk/python/odict.html
+# For information about bugfixes, updates and support, please join the
+# Pythonutils mailing list:
+# http://groups.google.com/group/pythonutils/
+# Comments, suggestions and bug reports welcome.
+
+"""A dict that keeps keys in insertion order"""
+from __future__ import generators
+
+__author__ = ('Nicola Larosa <nico-NoSp@m-tekNico.net>,'
+    'Michael Foord <fuzzyman AT voidspace DOT org DOT uk>')
+
+__docformat__ = "restructuredtext en"
+
+__revision__ = '$Id: odict.py 129 2005-09-12 18:15:28Z teknico $'
+
+__version__ = '0.2.2'
+
+__all__ = ['OrderedDict', 'SequenceOrderedDict']
+
+import sys
+INTP_VER = sys.version_info[:2]
+if INTP_VER < (2, 2):
+    raise RuntimeError("Python v.2.2 or later required")
+
+import types, warnings
+
+class OrderedDict(dict):
+    """
+    A class of dictionary that keeps the insertion order of keys.
+    
+    All appropriate methods return keys, items, or values in an ordered way.
+    
+    All normal dictionary methods are available. Update and comparison is
+    restricted to other OrderedDict objects.
+    
+    Various sequence methods are available, including the ability to explicitly
+    mutate the key ordering.
+    
+    __contains__ tests:
+    
+    >>> d = OrderedDict(((1, 3),))
+    >>> 1 in d
+    1
+    >>> 4 in d
+    0
+    
+    __getitem__ tests:
+    
+    >>> OrderedDict(((1, 3), (3, 2), (2, 1)))[2]
+    1
+    >>> OrderedDict(((1, 3), (3, 2), (2, 1)))[4]
+    Traceback (most recent call last):
+    KeyError: 4
+    
+    __len__ tests:
+    
+    >>> len(OrderedDict())
+    0
+    >>> len(OrderedDict(((1, 3), (3, 2), (2, 1))))
+    3
+    
+    get tests:
+    
+    >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+    >>> d.get(1)
+    3
+    >>> d.get(4) is None
+    1
+    >>> d.get(4, 5)
+    5
+    >>> d
+    OrderedDict([(1, 3), (3, 2), (2, 1)])
+    
+    has_key tests:
+    
+    >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+    >>> d.has_key(1)
+    1
+    >>> d.has_key(4)
+    0
+    """
+
+    def __init__(self, init_val=(), strict=False):
+        """
+        Create a new ordered dictionary. Cannot init from a normal dict,
+        nor from kwargs, since items order is undefined in those cases.
+        
+        If the ``strict`` keyword argument is ``True`` (``False`` is the
+        default) then when doing slice assignment - the ``OrderedDict`` you are
+        assigning from *must not* contain any keys in the remaining dict.
+        
+        >>> OrderedDict()
+        OrderedDict([])
+        >>> OrderedDict({1: 1})
+        Traceback (most recent call last):
+        TypeError: undefined order, cannot get items from dict
+        >>> OrderedDict({1: 1}.items())
+        OrderedDict([(1, 1)])
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d
+        OrderedDict([(1, 3), (3, 2), (2, 1)])
+        >>> OrderedDict(d)
+        OrderedDict([(1, 3), (3, 2), (2, 1)])
+        """
+        self.strict = strict
+        dict.__init__(self)
+        if isinstance(init_val, OrderedDict):
+            self._sequence = init_val.keys()
+            dict.update(self, init_val)
+        elif isinstance(init_val, dict):
+            # we lose compatibility with other ordered dict types this way
+            raise TypeError('undefined order, cannot get items from dict')
+        else:
+            self._sequence = []
+            self.update(init_val)
+
+### Special methods ###
+
+    def __delitem__(self, key):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> del d[3]
+        >>> d
+        OrderedDict([(1, 3), (2, 1)])
+        >>> del d[3]
+        Traceback (most recent call last):
+        KeyError: 3
+        >>> d[3] = 2
+        >>> d
+        OrderedDict([(1, 3), (2, 1), (3, 2)])
+        >>> del d[0:1]
+        >>> d
+        OrderedDict([(2, 1), (3, 2)])
+        """
+        if isinstance(key, types.SliceType):
+            # FIXME: efficiency?
+            keys = self._sequence[key]
+            for entry in keys:
+                dict.__delitem__(self, entry)
+            del self._sequence[key]
+        else:
+            # do the dict.__delitem__ *first* as it raises
+            # the more appropriate error
+            dict.__delitem__(self, key)
+            self._sequence.remove(key)
+
+    def __eq__(self, other):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d == OrderedDict(d)
+        True
+        >>> d == OrderedDict(((1, 3), (2, 1), (3, 2)))
+        False
+        >>> d == OrderedDict(((1, 0), (3, 2), (2, 1)))
+        False
+        >>> d == OrderedDict(((0, 3), (3, 2), (2, 1)))
+        False
+        >>> d == dict(d)
+        False
+        >>> d == False
+        False
+        """
+        if isinstance(other, OrderedDict):
+            # FIXME: efficiency?
+            #   Generate both item lists for each compare
+            return (self.items() == other.items())
+        else:
+            return False
+
+    def __lt__(self, other):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> c = OrderedDict(((0, 3), (3, 2), (2, 1)))
+        >>> c < d
+        True
+        >>> d < c
+        False
+        >>> d < dict(c)
+        Traceback (most recent call last):
+        TypeError: Can only compare with other OrderedDicts
+        """
+        if not isinstance(other, OrderedDict):
+            raise TypeError('Can only compare with other OrderedDicts')
+        # FIXME: efficiency?
+        #   Generate both item lists for each compare
+        return (self.items() < other.items())
+
+    def __le__(self, other):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> c = OrderedDict(((0, 3), (3, 2), (2, 1)))
+        >>> e = OrderedDict(d)
+        >>> c <= d
+        True
+        >>> d <= c
+        False
+        >>> d <= dict(c)
+        Traceback (most recent call last):
+        TypeError: Can only compare with other OrderedDicts
+        >>> d <= e
+        True
+        """
+        if not isinstance(other, OrderedDict):
+            raise TypeError('Can only compare with other OrderedDicts')
+        # FIXME: efficiency?
+        #   Generate both item lists for each compare
+        return (self.items() <= other.items())
+
+    def __ne__(self, other):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d != OrderedDict(d)
+        False
+        >>> d != OrderedDict(((1, 3), (2, 1), (3, 2)))
+        True
+        >>> d != OrderedDict(((1, 0), (3, 2), (2, 1)))
+        True
+        >>> d == OrderedDict(((0, 3), (3, 2), (2, 1)))
+        False
+        >>> d != dict(d)
+        True
+        >>> d != False
+        True
+        """
+        if isinstance(other, OrderedDict):
+            # FIXME: efficiency?
+            #   Generate both item lists for each compare
+            return not (self.items() == other.items())
+        else:
+            return True
+
+    def __gt__(self, other):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> c = OrderedDict(((0, 3), (3, 2), (2, 1)))
+        >>> d > c
+        True
+        >>> c > d
+        False
+        >>> d > dict(c)
+        Traceback (most recent call last):
+        TypeError: Can only compare with other OrderedDicts
+        """
+        if not isinstance(other, OrderedDict):
+            raise TypeError('Can only compare with other OrderedDicts')
+        # FIXME: efficiency?
+        #   Generate both item lists for each compare
+        return (self.items() > other.items())
+
+    def __ge__(self, other):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> c = OrderedDict(((0, 3), (3, 2), (2, 1)))
+        >>> e = OrderedDict(d)
+        >>> c >= d
+        False
+        >>> d >= c
+        True
+        >>> d >= dict(c)
+        Traceback (most recent call last):
+        TypeError: Can only compare with other OrderedDicts
+        >>> e >= d
+        True
+        """
+        if not isinstance(other, OrderedDict):
+            raise TypeError('Can only compare with other OrderedDicts')
+        # FIXME: efficiency?
+        #   Generate both item lists for each compare
+        return (self.items() >= other.items())
+
+    def __repr__(self):
+        """
+        Used for __repr__ and __str__
+        
+        >>> r1 = repr(OrderedDict((('a', 'b'), ('c', 'd'), ('e', 'f'))))
+        >>> r1
+        "OrderedDict([('a', 'b'), ('c', 'd'), ('e', 'f')])"
+        >>> r2 = repr(OrderedDict((('a', 'b'), ('e', 'f'), ('c', 'd'))))
+        >>> r2
+        "OrderedDict([('a', 'b'), ('e', 'f'), ('c', 'd')])"
+        >>> r1 == str(OrderedDict((('a', 'b'), ('c', 'd'), ('e', 'f'))))
+        True
+        >>> r2 == str(OrderedDict((('a', 'b'), ('e', 'f'), ('c', 'd'))))
+        True
+        """
+        return '%s([%s])' % (self.__class__.__name__, ', '.join(
+            ['(%r, %r)' % (key, self[key]) for key in self._sequence]))
+
+    def __setitem__(self, key, val):
+        """
+        Allows slice assignment, so long as the slice is an OrderedDict
+        >>> d = OrderedDict()
+        >>> d['a'] = 'b'
+        >>> d['b'] = 'a'
+        >>> d[3] = 12
+        >>> d
+        OrderedDict([('a', 'b'), ('b', 'a'), (3, 12)])
+        >>> d[:] = OrderedDict(((1, 2), (2, 3), (3, 4)))
+        >>> d
+        OrderedDict([(1, 2), (2, 3), (3, 4)])
+        >>> d[::2] = OrderedDict(((7, 8), (9, 10)))
+        >>> d
+        OrderedDict([(7, 8), (2, 3), (9, 10)])
+        >>> d = OrderedDict(((0, 1), (1, 2), (2, 3), (3, 4)))
+        >>> d[1:3] = OrderedDict(((1, 2), (5, 6), (7, 8)))
+        >>> d
+        OrderedDict([(0, 1), (1, 2), (5, 6), (7, 8), (3, 4)])
+        >>> d = OrderedDict(((0, 1), (1, 2), (2, 3), (3, 4)), strict=True)
+        >>> d[1:3] = OrderedDict(((1, 2), (5, 6), (7, 8)))
+        >>> d
+        OrderedDict([(0, 1), (1, 2), (5, 6), (7, 8), (3, 4)])
+        
+        >>> a = OrderedDict(((0, 1), (1, 2), (2, 3)), strict=True)
+        >>> a[3] = 4
+        >>> a
+        OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a[::1] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a
+        OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a[:2] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5)])
+        Traceback (most recent call last):
+        ValueError: slice assignment must be from unique keys
+        >>> a = OrderedDict(((0, 1), (1, 2), (2, 3)))
+        >>> a[3] = 4
+        >>> a
+        OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a[::1] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a
+        OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a[:2] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a
+        OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a[::-1] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> a
+        OrderedDict([(3, 4), (2, 3), (1, 2), (0, 1)])
+        
+        >>> d = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> d[:1] = 3
+        Traceback (most recent call last):
+        TypeError: slice assignment requires an OrderedDict
+        
+        >>> d = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
+        >>> d[:1] = OrderedDict([(9, 8)])
+        >>> d
+        OrderedDict([(9, 8), (1, 2), (2, 3), (3, 4)])
+        """
+        if isinstance(key, types.SliceType):
+            if not isinstance(val, OrderedDict):
+                # FIXME: allow a list of tuples?
+                raise TypeError('slice assignment requires an OrderedDict')
+            keys = self._sequence[key]
+            # NOTE: Could use ``range(*key.indices(len(self._sequence)))``
+            indexes = range(len(self._sequence))[key]
+            if key.step is None:
+                # NOTE: new slice may not be the same size as the one being
+                #   overwritten !
+                # NOTE: What is the algorithm for an impossible slice?
+                #   e.g. d[5:3]
+                pos = key.start or 0
+                del self[key]
+                newkeys = val.keys()
+                for k in newkeys:
+                    if k in self:
+                        if self.strict:
+                            raise ValueError('slice assignment must be from '
+                                'unique keys')
+                        else:
+                            # NOTE: This removes duplicate keys *first*
+                            #   so start position might have changed?
+                            del self[k]
+                self._sequence = (self._sequence[:pos] + newkeys +
+                    self._sequence[pos:])
+                dict.update(self, val)
+            else:
+                # extended slice - length of new slice must be the same
+                # as the one being replaced
+                if len(keys) != len(val):
+                    raise ValueError('attempt to assign sequence of size %s '
+                        'to extended slice of size %s' % (len(val), len(keys)))
+                # FIXME: efficiency?
+                del self[key]
+                item_list = zip(indexes, val.items())
+                # smallest indexes first - higher indexes not guaranteed to
+                # exist
+                item_list.sort()
+                for pos, (newkey, newval) in item_list:
+                    if self.strict and newkey in self:
+                        raise ValueError('slice assignment must be from unique'
+                            ' keys')
+                    self.insert(pos, newkey, newval)
+        else:
+            if key not in self:
+                self._sequence.append(key)
+            dict.__setitem__(self, key, val)
+
+    def __getitem__(self, key):
+        """
+        Allows slicing. Returns an OrderedDict if you slice.
+        >>> b = OrderedDict([(7, 0), (6, 1), (5, 2), (4, 3), (3, 4), (2, 5), (1, 6)])
+        >>> b[::-1]
+        OrderedDict([(1, 6), (2, 5), (3, 4), (4, 3), (5, 2), (6, 1), (7, 0)])
+        >>> b[2:5]
+        OrderedDict([(5, 2), (4, 3), (3, 4)])
+        >>> type(b[2:4])
+        <class '__main__.OrderedDict'>
+        """
+        if isinstance(key, types.SliceType):
+            # FIXME: does this raise the error we want?
+            keys = self._sequence[key]
+            # FIXME: efficiency?
+            return OrderedDict([(entry, self[entry]) for entry in keys])
+        else:
+            return dict.__getitem__(self, key)
+
+    __str__ = __repr__
+
+    def __setattr__(self, name, value):
+        """
+        Implemented so that accesses to ``sequence`` raise a warning and are
+        diverted to the new ``setkeys`` method.
+        """
+        if name == 'sequence':
+            warnings.warn('Use of the sequence attribute is deprecated.'
+                ' Use the keys method instead.', DeprecationWarning)
+            # NOTE: doesn't return anything
+            self.setkeys(value)
+        else:
+            # FIXME: do we want to allow arbitrary setting of attributes?
+            #   Or do we want to manage it?
+            object.__setattr__(self, name, value)
+
+    def __getattr__(self, name):
+        """
+        Implemented so that access to ``sequence`` raises a warning.
+        
+        >>> d = OrderedDict()
+        >>> d.sequence
+        []
+        """
+        if name == 'sequence':
+            warnings.warn('Use of the sequence attribute is deprecated.'
+                ' Use the keys method instead.', DeprecationWarning)
+            # NOTE: Still (currently) returns a direct reference. Need to
+            #   because code that uses sequence will expect to be able to
+            #   mutate it in place.
+            return self._sequence
+        else:
+            # raise the appropriate error
+            raise AttributeError("OrderedDict has no '%s' attribute" % name)
+
+    def __deepcopy__(self, memo):
+        """
+        To allow deepcopy to work with OrderedDict.
+        
+        >>> from copy import deepcopy
+        >>> a = OrderedDict([(1, 1), (2, 2), (3, 3)])
+        >>> a['test'] = {}
+        >>> b = deepcopy(a)
+        >>> b == a
+        True
+        >>> b is a
+        False
+        >>> a['test'] is b['test']
+        False
+        """
+        from copy import deepcopy
+        return self.__class__(deepcopy(self.items(), memo), self.strict)
+
+
+### Read-only methods ###
+
+    def copy(self):
+        """
+        >>> OrderedDict(((1, 3), (3, 2), (2, 1))).copy()
+        OrderedDict([(1, 3), (3, 2), (2, 1)])
+        """
+        return OrderedDict(self)
+
+    def items(self):
+        """
+        ``items`` returns a list of tuples representing all the 
+        ``(key, value)`` pairs in the dictionary.
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.items()
+        [(1, 3), (3, 2), (2, 1)]
+        >>> d.clear()
+        >>> d.items()
+        []
+        """
+        return zip(self._sequence, self.values())
+
+    def keys(self):
+        """
+        Return a list of keys in the ``OrderedDict``.
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.keys()
+        [1, 3, 2]
+        """
+        return self._sequence[:]
+
+    def values(self, values=None):
+        """
+        Return a list of all the values in the OrderedDict.
+        
+        Optionally you can pass in a list of values, which will replace the
+        current list. The value list must be the same len as the OrderedDict.
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.values()
+        [3, 2, 1]
+        """
+        return [self[key] for key in self._sequence]
+
+    def iteritems(self):
+        """
+        >>> ii = OrderedDict(((1, 3), (3, 2), (2, 1))).iteritems()
+        >>> ii.next()
+        (1, 3)
+        >>> ii.next()
+        (3, 2)
+        >>> ii.next()
+        (2, 1)
+        >>> ii.next()
+        Traceback (most recent call last):
+        StopIteration
+        """
+        def make_iter(self=self):
+            keys = self.iterkeys()
+            while True:
+                key = keys.next()
+                yield (key, self[key])
+        return make_iter()
+
+    def iterkeys(self):
+        """
+        >>> ii = OrderedDict(((1, 3), (3, 2), (2, 1))).iterkeys()
+        >>> ii.next()
+        1
+        >>> ii.next()
+        3
+        >>> ii.next()
+        2
+        >>> ii.next()
+        Traceback (most recent call last):
+        StopIteration
+        """
+        return iter(self._sequence)
+
+    __iter__ = iterkeys
+
+    def itervalues(self):
+        """
+        >>> iv = OrderedDict(((1, 3), (3, 2), (2, 1))).itervalues()
+        >>> iv.next()
+        3
+        >>> iv.next()
+        2
+        >>> iv.next()
+        1
+        >>> iv.next()
+        Traceback (most recent call last):
+        StopIteration
+        """
+        def make_iter(self=self):
+            keys = self.iterkeys()
+            while True:
+                yield self[keys.next()]
+        return make_iter()
+
+### Read-write methods ###
+
+    def clear(self):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.clear()
+        >>> d
+        OrderedDict([])
+        """
+        dict.clear(self)
+        self._sequence = []
+
+    def pop(self, key, *args):
+        """
+        No dict.pop in Python 2.2, gotta reimplement it
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.pop(3)
+        2
+        >>> d
+        OrderedDict([(1, 3), (2, 1)])
+        >>> d.pop(4)
+        Traceback (most recent call last):
+        KeyError: 4
+        >>> d.pop(4, 0)
+        0
+        >>> d.pop(4, 0, 1)
+        Traceback (most recent call last):
+        TypeError: pop expected at most 2 arguments, got 3
+        """
+        if len(args) > 1:
+            raise TypeError, ('pop expected at most 2 arguments, got %s' %
+                (len(args) + 1))
+        if key in self:
+            val = self[key]
+            del self[key]
+        else:
+            try:
+                val = args[0]
+            except IndexError:
+                raise KeyError(key)
+        return val
+
+    def popitem(self, i=-1):
+        """
+        Delete and return an item specified by index, not a random one as in
+        dict. The index is -1 by default (the last item).
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.popitem()
+        (2, 1)
+        >>> d
+        OrderedDict([(1, 3), (3, 2)])
+        >>> d.popitem(0)
+        (1, 3)
+        >>> OrderedDict().popitem()
+        Traceback (most recent call last):
+        KeyError: 'popitem(): dictionary is empty'
+        >>> d.popitem(2)
+        Traceback (most recent call last):
+        IndexError: popitem(): index 2 not valid
+        """
+        if not self._sequence:
+            raise KeyError('popitem(): dictionary is empty')
+        try:
+            key = self._sequence[i]
+        except IndexError:
+            raise IndexError('popitem(): index %s not valid' % i)
+        return (key, self.pop(key))
+
+    def setdefault(self, key, defval = None):
+        """
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.setdefault(1)
+        3
+        >>> d.setdefault(4) is None
+        True
+        >>> d
+        OrderedDict([(1, 3), (3, 2), (2, 1), (4, None)])
+        >>> d.setdefault(5, 0)
+        0
+        >>> d
+        OrderedDict([(1, 3), (3, 2), (2, 1), (4, None), (5, 0)])
+        """
+        if key in self:
+            return self[key]
+        else:
+            self[key] = defval
+            return defval
+
+    def update(self, from_od):
+        """
+        Update from another OrderedDict or sequence of (key, value) pairs
+        
+        >>> d = OrderedDict(((1, 0), (0, 1)))
+        >>> d.update(OrderedDict(((1, 3), (3, 2), (2, 1))))
+        >>> d
+        OrderedDict([(1, 3), (0, 1), (3, 2), (2, 1)])
+        >>> d.update({4: 4})
+        Traceback (most recent call last):
+        TypeError: undefined order, cannot get items from dict
+        >>> d.update((4, 4))
+        Traceback (most recent call last):
+        TypeError: cannot convert dictionary update sequence element "4" to a 2-item sequence
+        """
+        if isinstance(from_od, OrderedDict):
+            for key, val in from_od.items():
+                self[key] = val
+        elif isinstance(from_od, dict):
+            # we lose compatibility with other ordered dict types this way
+            raise TypeError('undefined order, cannot get items from dict')
+        else:
+            # FIXME: efficiency?
+            # sequence of 2-item sequences, or error
+            for item in from_od:
+                try:
+                    key, val = item
+                except TypeError:
+                    raise TypeError('cannot convert dictionary update'
+                        ' sequence element "%s" to a 2-item sequence' % item)
+                self[key] = val
+
+    def rename(self, old_key, new_key):
+        """
+        Rename the key for a given value, without modifying sequence order.
+        
+        For the case where new_key already exists this raise an exception,
+        since if new_key exists, it is ambiguous as to what happens to the
+        associated values, and the position of new_key in the sequence.
+        
+        >>> od = OrderedDict()
+        >>> od['a'] = 1
+        >>> od['b'] = 2
+        >>> od.items()
+        [('a', 1), ('b', 2)]
+        >>> od.rename('b', 'c')
+        >>> od.items()
+        [('a', 1), ('c', 2)]
+        >>> od.rename('c', 'a')
+        Traceback (most recent call last):
+        ValueError: New key already exists: 'a'
+        >>> od.rename('d', 'b')
+        Traceback (most recent call last):
+        KeyError: 'd'
+        """
+        if new_key == old_key:
+            # no-op
+            return
+        if new_key in self:
+            raise ValueError("New key already exists: %r" % new_key)
+        # rename sequence entry
+        value = self[old_key] 
+        old_idx = self._sequence.index(old_key)
+        self._sequence[old_idx] = new_key
+        # rename internal dict entry
+        dict.__delitem__(self, old_key)
+        dict.__setitem__(self, new_key, value)
+
+    def setitems(self, items):
+        """
+        This method allows you to set the items in the dict.
+        
+        It takes a list of tuples - of the same sort returned by the ``items``
+        method.
+        
+        >>> d = OrderedDict()
+        >>> d.setitems(((3, 1), (2, 3), (1, 2)))
+        >>> d
+        OrderedDict([(3, 1), (2, 3), (1, 2)])
+        """
+        self.clear()
+        # FIXME: this allows you to pass in an OrderedDict as well :-)
+        self.update(items)
+
+    def setkeys(self, keys):
+        """
+        ``setkeys`` all ows you to pass in a new list of keys which will
+        replace the current set. This must contain the same set of keys, but
+        need not be in the same order.
+        
+        If you pass in new keys that don't match, a ``KeyError`` will be
+        raised.
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.keys()
+        [1, 3, 2]
+        >>> d.setkeys((1, 2, 3))
+        >>> d
+        OrderedDict([(1, 3), (2, 1), (3, 2)])
+        >>> d.setkeys(['a', 'b', 'c'])
+        Traceback (most recent call last):
+        KeyError: 'Keylist is not the same as current keylist.'
+        """
+        # FIXME: Efficiency? (use set for Python 2.4 :-)
+        # NOTE: list(keys) rather than keys[:] because keys[:] returns
+        #   a tuple, if keys is a tuple.
+        kcopy = list(keys)
+        kcopy.sort()
+        self._sequence.sort()
+        if kcopy != self._sequence:
+            raise KeyError('Keylist is not the same as current keylist.')
+        # NOTE: This makes the _sequence attribute a new object, instead
+        #       of changing it in place.
+        # FIXME: efficiency?
+        self._sequence = list(keys)
+
+    def setvalues(self, values):
+        """
+        You can pass in a list of values, which will replace the
+        current list. The value list must be the same len as the OrderedDict.
+        
+        (Or a ``ValueError`` is raised.)
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.setvalues((1, 2, 3))
+        >>> d
+        OrderedDict([(1, 1), (3, 2), (2, 3)])
+        >>> d.setvalues([6])
+        Traceback (most recent call last):
+        ValueError: Value list is not the same length as the OrderedDict.
+        """
+        if len(values) != len(self):
+            # FIXME: correct error to raise?
+            raise ValueError('Value list is not the same length as the '
+                'OrderedDict.')
+        self.update(zip(self, values))
+
+### Sequence Methods ###
+
+    def index(self, key):
+        """
+        Return the position of the specified key in the OrderedDict.
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.index(3)
+        1
+        >>> d.index(4)
+        Traceback (most recent call last):
+        ValueError: list.index(x): x not in list
+        """
+        return self._sequence.index(key)
+
+    def insert(self, index, key, value):
+        """
+        Takes ``index``, ``key``, and ``value`` as arguments.
+        
+        Sets ``key`` to ``value``, so that ``key`` is at position ``index`` in
+        the OrderedDict.
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.insert(0, 4, 0)
+        >>> d
+        OrderedDict([(4, 0), (1, 3), (3, 2), (2, 1)])
+        >>> d.insert(0, 2, 1)
+        >>> d
+        OrderedDict([(2, 1), (4, 0), (1, 3), (3, 2)])
+        >>> d.insert(8, 8, 1)
+        >>> d
+        OrderedDict([(2, 1), (4, 0), (1, 3), (3, 2), (8, 1)])
+        """
+        if key in self:
+            # FIXME: efficiency?
+            del self[key]
+        self._sequence.insert(index, key)
+        dict.__setitem__(self, key, value)
+
+    def reverse(self):
+        """
+        Reverse the order of the OrderedDict.
+        
+        >>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
+        >>> d.reverse()
+        >>> d
+        OrderedDict([(2, 1), (3, 2), (1, 3)])
+        """
+        self._sequence.reverse()
+
+    def sort(self, *args, **kwargs):
+        """
+        Sort the key order in the OrderedDict.
+        
+        This method takes the same arguments as the ``list.sort`` method on
+        your version of Python.
+        
+        >>> d = OrderedDict(((4, 1), (2, 2), (3, 3), (1, 4)))
+        >>> d.sort()
+        >>> d
+        OrderedDict([(1, 4), (2, 2), (3, 3), (4, 1)])
+        """
+        self._sequence.sort(*args, **kwargs)
+
+class Keys(object):
+    # FIXME: should this object be a subclass of list?
+    """
+    Custom object for accessing the keys of an OrderedDict.
+    
+    Can be called like the normal ``OrderedDict.keys`` method, but also
+    supports indexing and sequence methods.
+    """
+
+    def __init__(self, main):
+        self._main = main
+
+    def __call__(self):
+        """Pretend to be the keys method."""
+        return self._main._keys()
+
+    def __getitem__(self, index):
+        """Fetch the key at position i."""
+        # NOTE: this automatically supports slicing :-)
+        return self._main._sequence[index]
+
+    def __setitem__(self, index, name):
+        """
+        You cannot assign to keys, but you can do slice assignment to re-order
+        them.
+        
+        You can only do slice assignment if the new set of keys is a reordering
+        of the original set.
+        """
+        if isinstance(index, types.SliceType):
+            # FIXME: efficiency?
+            # check length is the same
+            indexes = range(len(self._main._sequence))[index]
+            if len(indexes) != len(name):
+                raise ValueError('attempt to assign sequence of size %s '
+                    'to slice of size %s' % (len(name), len(indexes)))
+            # check they are the same keys
+            # FIXME: Use set
+            old_keys = self._main._sequence[index]
+            new_keys = list(name)
+            old_keys.sort()
+            new_keys.sort()
+            if old_keys != new_keys:
+                raise KeyError('Keylist is not the same as current keylist.')
+            orig_vals = [self._main[k] for k in name]
+            del self._main[index]
+            vals = zip(indexes, name, orig_vals)
+            vals.sort()
+            for i, k, v in vals:
+                if self._main.strict and k in self._main:
+                    raise ValueError('slice assignment must be from '
+                        'unique keys')
+                self._main.insert(i, k, v)
+        else:
+            raise ValueError('Cannot assign to keys')
+
+    ### following methods pinched from UserList and adapted ###
+    def __repr__(self): return repr(self._main._sequence)
+
+    # FIXME: do we need to check if we are comparing with another ``Keys``
+    #   object? (like the __cast method of UserList)
+    def __lt__(self, other): return self._main._sequence <  other
+    def __le__(self, other): return self._main._sequence <= other
+    def __eq__(self, other): return self._main._sequence == other
+    def __ne__(self, other): return self._main._sequence != other
+    def __gt__(self, other): return self._main._sequence >  other
+    def __ge__(self, other): return self._main._sequence >= other
+    # FIXME: do we need __cmp__ as well as rich comparisons?
+    def __cmp__(self, other): return cmp(self._main._sequence, other)
+
+    def __contains__(self, item): return item in self._main._sequence
+    def __len__(self): return len(self._main._sequence)
+    def __iter__(self): return self._main.iterkeys()
+    def count(self, item): return self._main._sequence.count(item)
+    def index(self, item, *args): return self._main._sequence.index(item, *args)
+    def reverse(self): self._main._sequence.reverse()
+    def sort(self, *args, **kwds): self._main._sequence.sort(*args, **kwds)
+    def __mul__(self, n): return self._main._sequence*n
+    __rmul__ = __mul__
+    def __add__(self, other): return self._main._sequence + other
+    def __radd__(self, other): return other + self._main._sequence
+
+    ## following methods not implemented for keys ##
+    def __delitem__(self, i): raise TypeError('Can\'t delete items from keys')
+    def __iadd__(self, other): raise TypeError('Can\'t add in place to keys')
+    def __imul__(self, n): raise TypeError('Can\'t multiply keys in place')
+    def append(self, item): raise TypeError('Can\'t append items to keys')
+    def insert(self, i, item): raise TypeError('Can\'t insert items into keys')
+    def pop(self, i=-1): raise TypeError('Can\'t pop items from keys')
+    def remove(self, item): raise TypeError('Can\'t remove items from keys')
+    def extend(self, other): raise TypeError('Can\'t extend keys')
+
+class Items(object):
+    """
+    Custom object for accessing the items of an OrderedDict.
+    
+    Can be called like the normal ``OrderedDict.items`` method, but also
+    supports indexing and sequence methods.
+    """
+
+    def __init__(self, main):
+        self._main = main
+
+    def __call__(self):
+        """Pretend to be the items method."""
+        return self._main._items()
+
+    def __getitem__(self, index):
+        """Fetch the item at position i."""
+        if isinstance(index, types.SliceType):
+            # fetching a slice returns an OrderedDict
+            return self._main[index].items()
+        key = self._main._sequence[index]
+        return (key, self._main[key])
+
+    def __setitem__(self, index, item):
+        """Set item at position i to item."""
+        if isinstance(index, types.SliceType):
+            # NOTE: item must be an iterable (list of tuples)
+            self._main[index] = OrderedDict(item)
+        else:
+            # FIXME: Does this raise a sensible error?
+            orig = self._main.keys[index]
+            key, value = item
+            if self._main.strict and key in self and (key != orig):
+                raise ValueError('slice assignment must be from '
+                        'unique keys')
+            # delete the current one
+            del self._main[self._main._sequence[index]]
+            self._main.insert(index, key, value)
+
+    def __delitem__(self, i):
+        """Delete the item at position i."""
+        key = self._main._sequence[i]
+        if isinstance(i, types.SliceType):
+            for k in key:
+                # FIXME: efficiency?
+                del self._main[k]
+        else:
+            del self._main[key]
+
+    ### following methods pinched from UserList and adapted ###
+    def __repr__(self): return repr(self._main.items())
+
+    # FIXME: do we need to check if we are comparing with another ``Items``
+    #   object? (like the __cast method of UserList)
+    def __lt__(self, other): return self._main.items() <  other
+    def __le__(self, other): return self._main.items() <= other
+    def __eq__(self, other): return self._main.items() == other
+    def __ne__(self, other): return self._main.items() != other
+    def __gt__(self, other): return self._main.items() >  other
+    def __ge__(self, other): return self._main.items() >= other
+    def __cmp__(self, other): return cmp(self._main.items(), other)
+
+    def __contains__(self, item): return item in self._main.items()
+    def __len__(self): return len(self._main._sequence) # easier :-)
+    def __iter__(self): return self._main.iteritems()
+    def count(self, item): return self._main.items().count(item)
+    def index(self, item, *args): return self._main.items().index(item, *args)
+    def reverse(self): self._main.reverse()
+    def sort(self, *args, **kwds): self._main.sort(*args, **kwds)
+    def __mul__(self, n): return self._main.items()*n
+    __rmul__ = __mul__
+    def __add__(self, other): return self._main.items() + other
+    def __radd__(self, other): return other + self._main.items()
+
+    def append(self, item):
+        """Add an item to the end."""
+        # FIXME: this is only append if the key isn't already present
+        key, value = item
+        self._main[key] = value
+
+    def insert(self, i, item):
+        key, value = item
+        self._main.insert(i, key, value)
+
+    def pop(self, i=-1):
+        key = self._main._sequence[i]
+        return (key, self._main.pop(key))
+
+    def remove(self, item):
+        key, value = item
+        try:
+            assert value == self._main[key]
+        except (KeyError, AssertionError):
+            raise ValueError('ValueError: list.remove(x): x not in list')
+        else:
+            del self._main[key]
+
+    def extend(self, other):
+        # FIXME: is only a true extend if none of the keys already present
+        for item in other:
+            key, value = item
+            self._main[key] = value
+
+    def __iadd__(self, other):
+        self.extend(other)
+
+    ## following methods not implemented for items ##
+
+    def __imul__(self, n): raise TypeError('Can\'t multiply items in place')
+
+class Values(object):
+    """
+    Custom object for accessing the values of an OrderedDict.
+    
+    Can be called like the normal ``OrderedDict.values`` method, but also
+    supports indexing and sequence methods.
+    """
+
+    def __init__(self, main):
+        self._main = main
+
+    def __call__(self):
+        """Pretend to be the values method."""
+        return self._main._values()
+
+    def __getitem__(self, index):
+        """Fetch the value at position i."""
+        if isinstance(index, types.SliceType):
+            return [self._main[key] for key in self._main._sequence[index]]
+        else:
+            return self._main[self._main._sequence[index]]
+
+    def __setitem__(self, index, value):
+        """
+        Set the value at position i to value.
+        
+        You can only do slice assignment to values if you supply a sequence of
+        equal length to the slice you are replacing.
+        """
+        if isinstance(index, types.SliceType):
+            keys = self._main._sequence[index]
+            if len(keys) != len(value):
+                raise ValueError('attempt to assign sequence of size %s '
+                    'to slice of size %s' % (len(name), len(keys)))
+            # FIXME: efficiency?  Would be better to calculate the indexes
+            #   directly from the slice object
+            # NOTE: the new keys can collide with existing keys (or even
+            #   contain duplicates) - these will overwrite
+            for key, val in zip(keys, value):
+                self._main[key] = val
+        else:
+            self._main[self._main._sequence[index]] = value
+
+    ### following methods pinched from UserList and adapted ###
+    def __repr__(self): return repr(self._main.values())
+
+    # FIXME: do we need to check if we are comparing with another ``Values``
+    #   object? (like the __cast method of UserList)
+    def __lt__(self, other): return self._main.values() <  other
+    def __le__(self, other): return self._main.values() <= other
+    def __eq__(self, other): return self._main.values() == other
+    def __ne__(self, other): return self._main.values() != other
+    def __gt__(self, other): return self._main.values() >  other
+    def __ge__(self, other): return self._main.values() >= other
+    def __cmp__(self, other): return cmp(self._main.values(), other)
+
+    def __contains__(self, item): return item in self._main.values()
+    def __len__(self): return len(self._main._sequence) # easier :-)
+    def __iter__(self): return self._main.itervalues()
+    def count(self, item): return self._main.values().count(item)
+    def index(self, item, *args): return self._main.values().index(item, *args)
+
+    def reverse(self):
+        """Reverse the values"""
+        vals = self._main.values()
+        vals.reverse()
+        # FIXME: efficiency
+        self[:] = vals
+
+    def sort(self, *args, **kwds):
+        """Sort the values."""
+        vals = self._main.values()
+        vals.sort(*args, **kwds)
+        self[:] = vals
+
+    def __mul__(self, n): return self._main.values()*n
+    __rmul__ = __mul__
+    def __add__(self, other): return self._main.values() + other
+    def __radd__(self, other): return other + self._main.values()
+
+    ## following methods not implemented for values ##
+    def __delitem__(self, i): raise TypeError('Can\'t delete items from values')
+    def __iadd__(self, other): raise TypeError('Can\'t add in place to values')
+    def __imul__(self, n): raise TypeError('Can\'t multiply values in place')
+    def append(self, item): raise TypeError('Can\'t append items to values')
+    def insert(self, i, item): raise TypeError('Can\'t insert items into values')
+    def pop(self, i=-1): raise TypeError('Can\'t pop items from values')
+    def remove(self, item): raise TypeError('Can\'t remove items from values')
+    def extend(self, other): raise TypeError('Can\'t extend values')
+
+class SequenceOrderedDict(OrderedDict):
+    """
+    Experimental version of OrderedDict that has a custom object for ``keys``,
+    ``values``, and ``items``.
+    
+    These are callable sequence objects that work as methods, or can be
+    manipulated directly as sequences.
+    
+    Test for ``keys``, ``items`` and ``values``.
+    
+    >>> d = SequenceOrderedDict(((1, 2), (2, 3), (3, 4)))
+    >>> d
+    SequenceOrderedDict([(1, 2), (2, 3), (3, 4)])
+    >>> d.keys
+    [1, 2, 3]
+    >>> d.keys()
+    [1, 2, 3]
+    >>> d.setkeys((3, 2, 1))
+    >>> d
+    SequenceOrderedDict([(3, 4), (2, 3), (1, 2)])
+    >>> d.setkeys((1, 2, 3))
+    >>> d.keys[0]
+    1
+    >>> d.keys[:]
+    [1, 2, 3]
+    >>> d.keys[-1]
+    3
+    >>> d.keys[-2]
+    2
+    >>> d.keys[0:2] = [2, 1]
+    >>> d
+    SequenceOrderedDict([(2, 3), (1, 2), (3, 4)])
+    >>> d.keys.reverse()
+    >>> d.keys
+    [3, 1, 2]
+    >>> d.keys = [1, 2, 3]
+    >>> d
+    SequenceOrderedDict([(1, 2), (2, 3), (3, 4)])
+    >>> d.keys = [3, 1, 2]
+    >>> d
+    SequenceOrderedDict([(3, 4), (1, 2), (2, 3)])
+    >>> a = SequenceOrderedDict()
+    >>> b = SequenceOrderedDict()
+    >>> a.keys == b.keys
+    1
+    >>> a['a'] = 3
+    >>> a.keys == b.keys
+    0
+    >>> b['a'] = 3
+    >>> a.keys == b.keys
+    1
+    >>> b['b'] = 3
+    >>> a.keys == b.keys
+    0
+    >>> a.keys > b.keys
+    0
+    >>> a.keys < b.keys
+    1
+    >>> 'a' in a.keys
+    1
+    >>> len(b.keys)
+    2
+    >>> 'c' in d.keys
+    0
+    >>> 1 in d.keys
+    1
+    >>> [v for v in d.keys]
+    [3, 1, 2]
+    >>> d.keys.sort()
+    >>> d.keys
+    [1, 2, 3]
+    >>> d = SequenceOrderedDict(((1, 2), (2, 3), (3, 4)), strict=True)
+    >>> d.keys[::-1] = [1, 2, 3]
+    >>> d
+    SequenceOrderedDict([(3, 4), (2, 3), (1, 2)])
+    >>> d.keys[:2]
+    [3, 2]
+    >>> d.keys[:2] = [1, 3]
+    Traceback (most recent call last):
+    KeyError: 'Keylist is not the same as current keylist.'
+
+    >>> d = SequenceOrderedDict(((1, 2), (2, 3), (3, 4)))
+    >>> d
+    SequenceOrderedDict([(1, 2), (2, 3), (3, 4)])
+    >>> d.values
+    [2, 3, 4]
+    >>> d.values()
+    [2, 3, 4]
+    >>> d.setvalues((4, 3, 2))
+    >>> d
+    SequenceOrderedDict([(1, 4), (2, 3), (3, 2)])
+    >>> d.values[::-1]
+    [2, 3, 4]
+    >>> d.values[0]
+    4
+    >>> d.values[-2]
+    3
+    >>> del d.values[0]
+    Traceback (most recent call last):
+    TypeError: Can't delete items from values
+    >>> d.values[::2] = [2, 4]
+    >>> d
+    SequenceOrderedDict([(1, 2), (2, 3), (3, 4)])
+    >>> 7 in d.values
+    0
+    >>> len(d.values)
+    3
+    >>> [val for val in d.values]
+    [2, 3, 4]
+    >>> d.values[-1] = 2
+    >>> d.values.count(2)
+    2
+    >>> d.values.index(2)
+    0
+    >>> d.values[-1] = 7
+    >>> d.values
+    [2, 3, 7]
+    >>> d.values.reverse()
+    >>> d.values
+    [7, 3, 2]
+    >>> d.values.sort()
+    >>> d.values
+    [2, 3, 7]
+    >>> d.values.append('anything')
+    Traceback (most recent call last):
+    TypeError: Can't append items to values
+    >>> d.values = (1, 2, 3)
+    >>> d
+    SequenceOrderedDict([(1, 1), (2, 2), (3, 3)])
+    
+    >>> d = SequenceOrderedDict(((1, 2), (2, 3), (3, 4)))
+    >>> d
+    SequenceOrderedDict([(1, 2), (2, 3), (3, 4)])
+    >>> d.items()
+    [(1, 2), (2, 3), (3, 4)]
+    >>> d.setitems([(3, 4), (2 ,3), (1, 2)])
+    >>> d
+    SequenceOrderedDict([(3, 4), (2, 3), (1, 2)])
+    >>> d.items[0]
+    (3, 4)
+    >>> d.items[:-1]
+    [(3, 4), (2, 3)]
+    >>> d.items[1] = (6, 3)
+    >>> d.items
+    [(3, 4), (6, 3), (1, 2)]
+    >>> d.items[1:2] = [(9, 9)]
+    >>> d
+    SequenceOrderedDict([(3, 4), (9, 9), (1, 2)])
+    >>> del d.items[1:2]
+    >>> d
+    SequenceOrderedDict([(3, 4), (1, 2)])
+    >>> (3, 4) in d.items
+    1
+    >>> (4, 3) in d.items
+    0
+    >>> len(d.items)
+    2
+    >>> [v for v in d.items]
+    [(3, 4), (1, 2)]
+    >>> d.items.count((3, 4))
+    1
+    >>> d.items.index((1, 2))
+    1
+    >>> d.items.index((2, 1))
+    Traceback (most recent call last):
+    ValueError: list.index(x): x not in list
+    >>> d.items.reverse()
+    >>> d.items
+    [(1, 2), (3, 4)]
+    >>> d.items.reverse()
+    >>> d.items.sort()
+    >>> d.items
+    [(1, 2), (3, 4)]
+    >>> d.items.append((5, 6))
+    >>> d.items
+    [(1, 2), (3, 4), (5, 6)]
+    >>> d.items.insert(0, (0, 0))
+    >>> d.items
+    [(0, 0), (1, 2), (3, 4), (5, 6)]
+    >>> d.items.insert(-1, (7, 8))
+    >>> d.items
+    [(0, 0), (1, 2), (3, 4), (7, 8), (5, 6)]
+    >>> d.items.pop()
+    (5, 6)
+    >>> d.items
+    [(0, 0), (1, 2), (3, 4), (7, 8)]
+    >>> d.items.remove((1, 2))
+    >>> d.items
+    [(0, 0), (3, 4), (7, 8)]
+    >>> d.items.extend([(1, 2), (5, 6)])
+    >>> d.items
+    [(0, 0), (3, 4), (7, 8), (1, 2), (5, 6)]
+    """
+
+    def __init__(self, init_val=(), strict=True):
+        OrderedDict.__init__(self, init_val, strict=strict)
+        self._keys = self.keys
+        self._values = self.values
+        self._items = self.items
+        self.keys = Keys(self)
+        self.values = Values(self)
+        self.items = Items(self)
+        self._att_dict = {
+            'keys': self.setkeys,
+            'items': self.setitems,
+            'values': self.setvalues,
+        }
+
+    def __setattr__(self, name, value):
+        """Protect keys, items, and values."""
+        if not '_att_dict' in self.__dict__:
+            object.__setattr__(self, name, value)
+        else:
+            try:
+                fun = self._att_dict[name]
+            except KeyError:
+                OrderedDict.__setattr__(self, name, value)
+            else:
+                fun(value)
+
+if __name__ == '__main__':
+    if INTP_VER < (2, 3):
+        raise RuntimeError("Tests require Python v.2.3 or later")
+    # turn off warnings for tests
+    warnings.filterwarnings('ignore')
+    # run the code tests in doctest format
+    import doctest
+    m = sys.modules.get('__main__')
+    globs = m.__dict__.copy()
+    globs.update({
+        'INTP_VER': INTP_VER,
+    })
+    doctest.testmod(m, globs=globs)
+