/**
 * @ignore
 * attribute management and event in one
 * @author yiminghe@gmail.com, lifesinger@gmail.com
 */
KISSY.add('base', function (S, Attribute, EventCustom) {

    /**
     * @class KISSY.Base
     * @mixins KISSY.Event.Target
     * @mixins KISSY.Base.Attribute
     *
     * A base class which objects requiring attributes and custom event support can
     * extend. attributes configured
     * through the static {@link KISSY.Base#static-ATTRS} property for each class
     * in the hierarchy will be initialized by Base.
     */
    function Base(config) {
        var self = this,
            c = self.constructor;
        // save user config
        self.userConfig = config;
        // define
        while (c) {
            addAttrs(self, c['ATTRS']);
            c = c.superclass ? c.superclass.constructor : null;
        }
        // initial
        initAttrs(self, config);
    }


    /**
     * The default set of attributes which will be available for instances of this class, and
     * their configuration
     *
     * By default if the value is an object literal or an array it will be 'shallow' cloned, to
     * protect the default value.
     *
     *      for example:
     *      @example
     *              valueFn: // default function to get value
     *              getter: // getter function
     *              setter: // setter function
     *          }
     *      }
     *
     * @property ATTRS
     * @member KISSY.Base
     * @static
     * @type {Object}
     */


    function addAttrs(host, attrs) {
        if (attrs) {
            for (var attr in attrs) {
                // 子类上的 ATTRS 配置优先
                // 父类后加，父类不覆盖子类的相同设置
                // 属性对象会 merge
                // a: {y: {getter: fn}}, b: {y: {value: 3}}
                // b extends a
                // =>
                // b {y: {value: 3, getter: fn}}
                host.addAttr(attr, attrs[attr], false);
            }
        }
    }

    function initAttrs(host, config) {
        if (config) {
            for (var attr in config) {
                // 用户设置会调用 setter/validator 的，但不会触发属性变化事件
                host.setInternal(attr, config[attr]);
            }
        }
    }

    S.augment(Base, EventCustom.Target, Attribute);

    Base.Attribute = Attribute;

    S.Base = Base;

    return Base;
}, {
    requires: ['base/attribute', 'event/custom']
});
     *      {
     *          x:{
     *              value: // default value