Diretiva para adicionar campos com name dinâmico ao form, para validação

ng-name.directive.js

/*
 * https://groups.google.com/forum/?fromgroups=#!topic/angular/suCtNH10M2U
 * 
 * <p ng-repeat="campo in campos">
 *   <label>{{campo.label}}</label>
 *   <input ng-name="campo.name" />
 * </p>
 * 
 * formName[fieldName].$error.required
 */
  .directive('ngName', ['$interpolate', function ($interpolate) {
    return {
        restrict: 'A',
        require: ['ngModel', '^?form'],
        link: function (scope, element, attrs, ctrl) {
            var modelCtrl = ctrl[0];
            var formCtrl = ctrl[1] || {};
            modelCtrl.$name = ($interpolate('{{'+element.attr(attrs.$attr.ngName)+'}}'))(scope);
            return formCtrl.$addControl(modelCtrl);
        }
    };
  }])