Good way to dynamically open / close a popover (or tooltip) using angular, based on expression?

Question

I have a form that is wired into angular, using it for validation. I am able to display error messages using ng-show directives like so:

Answer 1

For others coming here, as of the 0.13.4 release, we have added the ability to programmatically open and close popovers via the *-is-open attribute on both tooltips and popovers in the Angular UI Bootstrap library. Thus, there is no longer any reason to have to roll your own code/solution.