i have a (non-working) example in http://jsfiddle.net/S2kc7/1/
You can make it work by using ng-change. Make sure that each radio has the ng-change on it
And you can use this logic in your controller
$scope.value= $scope.preval= 'foo';
$scope.validateChange = function() {
if(confirm('revert??? value='+$scope.value+' preval='+$scope.preval)) {
$scope.preval = $scope.value;
} else {
$scope.value = $scope.preval;
}
};
Updated and working fiddle http://jsfiddle.net/S2kc7/3/