Author: raymond.hettinger Date: Sat Jul 31 12:16:57 2010 New Revision: 83330 Log: Document how to change OrderedDict update order from first to last. Modified: python/branches/release31-maint/Doc/library/collections.rst Modified: python/branches/release31-maint/Doc/library/collections.rst ============================================================================== --- python/branches/release31-maint/Doc/library/collections.rst (original) +++ python/branches/release31-maint/Doc/library/collections.rst Sat Jul 31 12:16:57 2010 @@ -911,6 +911,18 @@ are deleted. But when new keys are added, the keys are appended to the end and the sort is not maintained. +It is also straight-forward to create an ordered dictionary variant +that the remembers the order the keys were *last* inserted. +If a new entry overwrites an existing entry, the +original insertion position is changed and moved to the end:: + + class LastUpdatedOrderedDict(OrderedDict): + 'Store items is the order the keys were last added' + def __setitem__(self, key, value): + if key in self: + del self[key] + OrderedDict.__setitem__(self, key, value) + :class:`UserDict` objects -------------------------