/**
                             * Provides a DataSource implementation which can be used to retrieve data from
                             * a custom function.
                             *
                             * @module datasource
                             * @submodule datasource-function
                             */
                            
                            /**
                             * Function subclass for the DataSource Utility.
                             * @class DataSource.Function
                             * @extends DataSource.Local
                             * @constructor
                             */
                            var LANG = Y.Lang,
                            
                                DSFn = function() {
                                    DSFn.superclass.constructor.apply(this, arguments);
                                };
                            
                            
                                /////////////////////////////////////////////////////////////////////////////
                                //
                                // DataSource.Function static properties
                                //
                                /////////////////////////////////////////////////////////////////////////////
                            Y.mix(DSFn, {
                                /**
                                 * Class name.
                                 *
                                 * @property NAME
                                 * @type String
                                 * @static
                                 * @final
                                 * @value "dataSourceFunction"
                                 */
                                NAME: "dataSourceFunction",
                            
                            
                                /////////////////////////////////////////////////////////////////////////////
                                //
                                // DataSource.Function Attributes
                                //
                                /////////////////////////////////////////////////////////////////////////////
                            
                                ATTRS: {
                                    /**
                                    * Stores the function that will serve the response data.
                                    *
                                    * @attribute source
                                    * @type {Any}
                                    * @default null
                                    */
                                    source: {
                                        validator: LANG.isFunction
                                    }
                                }
                            });
                            
                            Y.extend(DSFn, Y.DataSource.Local, {
                                /**
                                 * Passes query data to the source function. Fires <code>response</code>
                                 * event with the function results (synchronously).
                                 *
                                 * @method _defRequestFn
                                 * @param e {EventFacade} Event Facade with the following properties:
                                 * <dl>
                                 * <dt>tId (Number)</dt> <dd>Unique transaction ID.</dd>
                                 * <dt>request (Object)</dt> <dd>The request.</dd>
                                 * <dt>callback (Object)</dt> <dd>The callback object with the following
                                 * properties:
                                 *     <dl>
                                 *         <dt>success (Function)</dt> <dd>Success handler.</dd>
                                 *         <dt>failure (Function)</dt> <dd>Failure handler.</dd>
                                 *     </dl>
                                 * </dd>
                                 * <dt>cfg (Object)</dt> <dd>Configuration object.</dd>
                                 * </dl>
                                 * @protected
                                 */
                                _defRequestFn: function(e) {
                                    var fn = this.get("source"),
                                        payload = e.details[0];
                            
                                    if (fn) {
                                        try {
                                            payload.data = fn(e.request, this, e);
                                        } catch (ex) {
                                            Y.log("Function execution failure", "error", "datasource-function");
                                            payload.error = ex;
                                        }
                                    } else {
                                        Y.log("Function data failure", "error", "datasource-function");
                                        payload.error = new Error("Function data failure");
                                    }
                            
                                    this.fire("data", payload);
                            
                                    return e.tId;
                                }
                            });
                            
                            Y.DataSource.Function = DSFn;