求解释一下Angular.js里面的控制器的结构。

[申祷无]

function TodoCtrl($scope) {
  $scope.todos = [
    {text:'learn angular', done:true},
    {text:'build an angular app', done:false}];
 
  $scope.addTodo = function() {
    $scope.todos.push({text:$scope.todoText, done:false});
    $scope.todoText = '';
  };
 
  $scope.remaining = function() {
    var count = 0;
    angular.forEach($scope.todos, function(todo) {
      count += todo.done ? 0 : 1;
    });
    return count;
  };
 
  $scope.archive = function() {
    var oldTodos = $scope.todos;
    $scope.todos = [];
    angular.forEach(oldTodos, function(todo) {
      if (!todo.done) $scope.todos.push(todo);
    });
  };
}

来源：http://angularjs.org/#add-some-control

这是闭包么？看书的时候闭包我就一直没看明白，之后也没有详细研究。
另外Angular.js是怎么操作那个$scope的？至少Angular.js应该需要向$scope添加todoText吧？TodoCtrl函数外面怎么访问那个$scope？

[KK3K2005]

鼠标移上去有详细解释