/**
     * The attribute module provides an augmentable Attribute implementation, which
     * adds configurable attributes and attribute change events to the class being
     * augmented. It also provides a State class, which is used internally by Attribute,
     * but can also be used independently to provide a name/property/value data structure to
     * store state.
     *
     * @module attribute
     */

    /**
     * The attribute-base submodule provides core attribute handling support, with everything
     * aside from complex attribute handling in the provider's constructor.
     *
     * @module attribute
     * @submodule attribute-base
     */

    /**
     * <p>
     * Attribute provides configurable attribute support along with attribute change events. It is designed to be
     * augmented on to a host class, and provides the host with the ability to configure attributes to store and retrieve state,
     * along with attribute change events.
     * </p>
     * <p>For example, attributes added to the host can be configured:</p>
     * <ul>
     *     <li>As read only.</li>
     *     <li>As write once.</li>
     *     <li>With a setter function, which can be used to manipulate
     *     values passed to Attribute's <a href="#method_set">set</a> method, before they are stored.</li>
     *     <li>With a getter function, which can be used to manipulate stored values,
     *     before they are returned by Attribute's <a href="#method_get">get</a> method.</li>
     *     <li>With a validator function, to validate values before they are stored.</li>
     * </ul>
     *
     * <p>See the <a href="#method_addAttr">addAttr</a> method, for the complete set of configuration
     * options available for attributes.</p>
     *
     * <p><strong>NOTE:</strong> Most implementations will be better off extending the <a href="Base.html">Base</a> class,
     * instead of augmenting Attribute directly. Base augments Attribute and will handle the initial configuration
     * of attributes for derived classes, accounting for values passed into the constructor.</p>
     *
     * @class Attribute
     * @param attrs {Object} The attributes to add during construction (passed through to <a href="#method_addAttrs">addAttrs</a>).
     *        These can also be defined on the constructor being augmented with Attribute by defining the ATTRS property on the constructor.
     * @param values {Object} The initial attribute values to apply (passed through to <a href="#method_addAttrs">addAttrs</a>).
     *        These are not merged/cloned. The caller is responsible for isolating user provided values if required.
     * @param lazy {boolean} Whether or not to add attributes lazily (passed through to <a href="#method_addAttrs">addAttrs</a>).
     * @uses AttributeCore
     * @uses AttributeObservable
     * @uses EventTarget
     * @uses AttributeExtras
     */
    function Attribute() {
        Y.AttributeCore.apply(this, arguments);
        Y.AttributeObservable.apply(this, arguments);
        Y.AttributeExtras.apply(this, arguments);
    }

    Y.mix(Attribute, Y.AttributeCore, false, null, 1);
    Y.mix(Attribute, Y.AttributeExtras, false, null, 1);

    // Needs to be `true`, to overwrite methods from AttributeCore
    Y.mix(Attribute, Y.AttributeObservable, true, null, 1);

    /**
     * <p>The value to return from an attribute setter in order to prevent the set from going through.</p>
     *
     * <p>You can return this value from your setter if you wish to combine validator and setter
     * functionality into a single setter function, which either returns the massaged value to be stored or
     * AttributeCore.INVALID_VALUE to prevent invalid values from being stored.</p>
     *
     * @property INVALID_VALUE
     * @type Object
     * @static
     * @final
     */
    Attribute.INVALID_VALUE = Y.AttributeCore.INVALID_VALUE;

    /**
     * The list of properties which can be configured for
     * each attribute (e.g. setter, getter, writeOnce etc.).
     *
     * This property is used internally as a whitelist for faster
     * Y.mix operations.
     *
     * @property _ATTR_CFG
     * @type Array
     * @static
     * @protected
     */
    Attribute._ATTR_CFG = Y.AttributeCore._ATTR_CFG.concat(Y.AttributeObservable._ATTR_CFG);

    /**
     * Utility method to protect an attribute configuration hash, by merging the
     * entire object and the individual attr config objects.
     *
     * @method protectAttrs
     * @static
     * @param {Object} attrs A hash of attribute to configuration object pairs.
     * @return {Object} A protected version of the `attrs` argument.
     */
    Attribute.protectAttrs = Y.AttributeCore.protectAttrs;

    Y.Attribute = Attribute;