3.0.0

* set/get can now be called for ad-hoc attributes (attributes which 

  have not been added/configured).

* Fixed issue where custom getters were being called with undefined values,

  for the initial set.

* Limited the case for which an attribute will not notify after listeners, 

  if the value is unchanged after a set, to primitive values (values for 

  which Lang.isObject(newVal) returns false).

  This allows after listeners to be invoked, when resetting the value to 

  the same object reference, which has properties updated, or arrays with

  elements modified. 

* Attribute broken up into attribute-base and attribute-complex submodules.

  attribute-complex adds support for complex attributes ({x.y.z : 5}) to

  addAttrs. 

3.0.0 beta 1

* Removed Attribute.CLONE support in the interests of simplicity.

  Was not being used. Can re-evaluate support if real world demand 

  for it exists. 

* Changed "set" and "get" configuration properties for setter and 

  getter methods to "setter" and "getter" respectively.

* Added support for setter to return Attribute.INVALID_VALUE

  to prevent attribute state from being changed. 

  This allows developers to combine setter and validator 

  functionality into one method if performance optimization 

  is required.

* "validator" is now invoked before "setter".

* Renamed xxxAtt and xxxAtts methods to xxxAttr, xxxAttrs for

  consistency.

* "after" listeners are only notified if attribute value really

  changes (preVal !== newVal).

* Extending classes can now overwrite ATTRS configuration properties 

  from super classes, including writeOnce and readOnly attributes.

  The ATTRS configurations are merged across the class hierarchy,

  before they are used to initialize the attributes.

* addAttr now prevents re-adding attributes which are already 

  configured in order to maintain consistent state.

* Event prefix wrapper functions (on, after etc.) removed - 

  Event.Target now accepts an event prefix configuration value

* Added additional log messages to assist with debugging.

* Attribute change events are no longer fired for initial set.

* Split up State add/get/remove into add/addAll, get/getAll, 

  remove/removeAll to avoid having to create object literals for 

  critical path [ add/get single key values ].

* Attribute getter, setter, validator now also receive attribute name 

  as the 2nd arg (val, name).

* If Attributes initialized through addAttrs have a user provided value 

  which is not valid, the initial attribute value will revert to the 

  default value in the attribute configuration, if it exists.

* reset() no longer resets readOnly or writeOnce attributes. Only 

  publically settable values are reset.

* Added modifyAttr method, to allow component developer to modify 

  configuration of an attribute which has already been added. The set of 

  attribute configuration properties which can be modified after it 

  has been added are limited to getter, readOnly, writeOnce and broadcast.

* Added support for lazy attribute configuration. Base uses this feature 

  to lazily intialize all Attributes on the first call to get/set, for 

  performance optimization. 

  lazyAdd:true/false can be used to over-ride this behavior for a 

  particular attribute. 

3.0.0PR2

* Added valueFn support, to allowing static 

  attribute values configuration to set instance

  based values.

* Added reset method.

* Added private setter for use by class implementation

  code to set readOnly, writeOnce values.

3.0.0PR1 - Initial release

Module Name: "attribute"

Documentation: http://developer.yahoo.com/yui/3/attribute

The Attribute utility allows you to add attributes to any class 

through an augmentable Attribute interface. The interface adds 

get and set methods to your class for attribute access, in 

addition to supporting change events allowing you to listen 

for changes in attribute values.