how to 'watch' values in directive link function

From Christian GROBMEIER

from Processing json from the attribute:

directives.directive('tabLoad', function() {      return {              link: function (scope, element, attrs) {                  attrs.$observe('tabLoad', function(val) {                      var data = angular.fromJson(val);                      console.log(data);                      console.log(data.test);                      // do something                  });              }          }  });