Function addAttrInterpolateDirective

test/angular/1.2/angular.js:7070–7126

(node, directives, value, name)

    function addAttrInterpolateDirective(node, directives, value, name) {
      var interpolateFn = $interpolate(value, true);

      // no interpolation found -> ignore
      if (!interpolateFn) return;


      if (name === "multiple" && nodeName_(node) === "SELECT") {
        throw $compileMinErr("selmulti",
            "Binding to the 'multiple' attribute is not supported. Element: {0}",
            startingTag(node));
      }

      directives.push({
        priority: 100,
        compile: function() {
            return {
              pre: function attrInterpolatePreLinkFn(scope, element, attr) {
                var $$observers = (attr.$$observers || (attr.$$observers = {}));

                if (EVENT_HANDLER_ATTR_REGEXP.test(name)) {
                  throw $compileMinErr('nodomevents',
                      "Interpolations for HTML DOM event attributes are disallowed.  Please use the " +
                          "ng- versions (such as ng-click instead of onclick) instead.");
                }

                // we need to interpolate again, in case the attribute value has been updated
                // (e.g. by another directive's compile function)
                interpolateFn = $interpolate(attr[name], true, getTrustedContext(node, name));

                // if attribute was updated so that there is no interpolation going on we don't want to
                // register any observers
                if (!interpolateFn) return;

                // TODO(i): this should likely be attr.$set(name, iterpolateFn(scope) so that we reset the
                // actual attr value
                attr[name] = interpolateFn(scope);
                ($$observers[name] || ($$observers[name] = [])).$$inter = true;
                (attr.$$observers && attr.$$observers[name].$$scope || scope).
                  $watch(interpolateFn, function interpolateFnWatchAction(newValue, oldValue) {
                    //special case for class attribute addition + removal
                    //so that class changes can tap into the animation
                    //hooks provided by the $animate service. Be sure to
                    //skip animations when the first digest occurs (when
                    //both the new and the old values are the same) since
                    //the CSS classes are the non-interpolated values
                    if(name === 'class' && newValue != oldValue) {
                      attr.$updateClass(newValue, oldValue);
                    } else {
                      attr.$set(name, newValue);
                    }
                  });
              }
            };
          }
      });
    }