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.

3.4.0

* Added params to constructor, to support call to addAttrs on construction

with user values, when augmenting and invoking constructor manually.

Also broke out addAttrs logic on construction (introduced for Node),

into it's own _initAttrs method to facilitate customization.

3.3.0

* Changed instanceof to Y.instanceOf, to prevent leaks in IE7

3.2.0

* Added protected helper method (_getAttrCfg) to return the configuration

for a given attribute.

3.1.1

* Fixed ticket #2528753 : Sub attribute value crashed after setting another sub attribute.

3.1.0

* writeOnce can be set to "initOnly", which can be used

to prevent the user from setting the value outside of the initial

configuration when using the addAttrs.

When used with Base, this means that the user can only define a

value for the Attribute during construction.

* Attribute change events are now published with the defaultTargetOnly property set to true.

* newVal property of event object passed to change event listeners will now be the value returned from the Attribute's getter (if defined)

* setter, getter, validator and valueFn can now be specified as

strings, referring to the method names to be invoked on the Attribute

instance.

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