Prototype和Ajax.Request范围

我在原型的Ajax.Request类中获取正确的范围时遇到了麻烦.我要做的是编写一个包含ajax请求的简单API:

API = Class.create({

  initialize:function(api_token)
  {
    this.api_token = api_token;
    this.request_uri = new Template('/api/#{api_token}/#{resource}.json');
    this.status = 0;
    this.last_result = null;
  },

  some_api_call:function()
  {
    var result = this._request('resource', {'id':1});
    // and so on...
  },

  _request:function(resource, params)
  {
    var uri = this.request_uri.evaluate({"api_token":this.api_token,"resource":resource});
    new Ajax.Request(uri,
    {
      contentType:'application/json',
      method:'get',
      parameters:params,
      onSuccess:function(r)
      {
        alert(this);
        this.last_result = r.responseJSON;
        this.status = r.status;
      }
    });    
    return this.last_result;
  }

});

当我在onSuccess()方法中时,我期望+ this +来引用父对象,但是它给了我DOMWindow.我似乎无法将响应数据放入API类中.我认为这是一个愚蠢的事情(绑定？),但我今天似乎无法想到这一点.

谢谢

好的.我错过了更大的问题.我请求异步所以它被设置的结果,只是没有马上.公平地说,这也是一个具有约束力的问题.这是正确的要求:

_request:function(resource, params)
{
  var uri = this.request_uri.evaluate({"api_token":this.api_token,"resource":resource});
  new Ajax.Request(uri,
  {
    asynchronous: false,
    contentType:'application/json',
    method:'get',
    parameters:params,
    onSuccess:function(r)
    {
      this.last_result = r.responseJSON;
      this.status = r.status;
    }.bind(this)
  });    

  alert(this.status);

  return this.last_result;
}