Private variabes in the controller scope

Private variabes in the controller scope

In angular, following the demos, I can define a controller as:
function TodoCtrl($scope) {
$scope.todos = [
{text:'learn angular', done:true},
{text:'build an angular app', done:false},
{text:'empty dishwasher', done:false}];
$scope.oldtodos = [];
var oldtodos2 = [];
...
You'll note that have two oldtodos. One on the $scope and one just just a
local var. I think the later approach is the way to go if you want to
encapsulate this variable - i.e. no-one other than the controller has any
interest in it and the former is good if you want to pass the variable
back to the model
Are my correct?
Thanks