javascript - Why is the Angular digest loop different on UI events, $timeout and $http? -

i have been working on lib angular, using 1.2.27, , surprise looking @ result:

$scope.myclickmethod = function () {   $scope.$$phase; // $apply   $scope.$apply(); // gives digest error, of course };  $timeout(function () {   $scope.$$phase; // null   $scope.$apply(); // not give digest error });  $http.get('/').then(function () {   $scope.$$phase; // $digest   $scope.$apply(); // gives digest error }); 

the problem can not identify digest loop ready run when using $timeout, $http etc. ng-clicks etc. questions is... why different? thought angular did in both cases:

$scope.myclickmethod = function angularwrapper () {   $rootscope.$apply(function myoriginalmethod () {     // code   }); };  $timeout(function angularwrapper () {   $rootscope.$apply(function myoriginaltimoutfunction () {     // code   }); }); 

why $$phase = $apply on ui-events, $$phase = $digest on $http , $$phase = null on $timeout? async in nature, not make sense behave differently. sure there reason though. know?

i see 1.3 has changes $http new $applyasync method. not tested though.

the $timeout callback called @ end of digest loop.

so, because outside digest loop, can call $apply , recall entire digest loop.

for other methods (ng-click, $http), called during digest loop. calling $apply give error because angularjs doesn't want digest loop in digest loop.