Why ngIf has higher priority than {{ }} (interpolate)?

Question

What is the reasoning behind setting ngIf priority (600) higher than {{ }}(100)? Shouldn\'t it have a lower priority to allow {{ }} in

Answer 1

ng-if expects its value to be an angular expression - under the hood it just makes use of $scope.$watch. Therefore, if you want to condition including content of ng-if on some variable defined on the scope (let say: scope.hide), you put ng-if="hide" in your mark-up. No double curly braces here.

Now back to your question: it is true that ng-if has priority of 600, but $interpolate is angular's service - not a directive. As such $interpolate does not define priority. Where did you get 100 from?

UPDATE

You can always condition including content of ng-if on some function (let say scope.conditionFn) by putting in your mark-up: ng-if="conditionFn()".

UPDATE 2

I updated your PLNKR to make it working. The inconsistencies between ng-if and ng-hide in your plunker had nothing to do with priority of interpolation taking place in $compile.

UPDATE 3

It seems that you are right that order of interpolation plays a role here, but... I really do not see any good reason to interpolate inside of angular's expression. The reason why ng-if has relatively high priority is that it removes/adds transcluded content from/to DOM, whereas ng-hide just shows/hides the transcluded content. I think it is a pure coincidence that one directive seems to work and the other not. But if you do not use unnecessary, superfluous tricks, both do work as intended, what my plunker shows.