当使用大量异步代码时，我对如何编写像样的代码感到困惑。

在下面的代码片段中，我登录以获取身份验证 cookie 并将该 cookie 用于下一个请求以获取项目名称列表(作为示例):

def self.populateProjectsTable(projects_controller) 
  payload = {email: "email", password: "pass"} 
  HTTP.post("http://example.com/login", {payload: payload}) do |response| 
    authCookie = response.headers['Set-Cookie'] 
    HTTP.get("http://example.com/projects.json", {cookie: authCookie}) do |response| 
      projects = JSON.parse(response.body.to_str) 
      projects_controller.projects = projects 
      projects_controller.reloadData 
    end 
  end 
end 

虽然这会起作用，但代码感觉很脏。没有真正遵循单一职责原则。我想用几种方法提取它:

def self.populateProjectsTable(projects_controller) 
  @taskList = TaskList.new 
  @taskList.doLogin 
  projects = @taskList.getProjects 
  projects_controller.projects = projects 
  projects_controller.reloadData 
end 
 
def doLogin 
  payload = {email: "email", password: "pass"} 
  HTTP.post("http://example.com/login", {payload: payload}) do |response| 
    @authCookie = response.headers['Set-Cookie'] 
  end 
end 
 
def getProjects 
  HTTP.get("http://example.com/projects.json", {cookie: @authCookie}) do |response| 
    projects = JSON.parse(response.body.to_str) 
  end 
end 

这显然行不通。 getProjects 方法在 doLogin 完成之前调用，项目仅在 block 范围内已知，不会将数据返回给 populateProjectsTable 方法。

如何在没有第一个示例中所示的嵌套的情况下编写此类应用程序？

请您参考如下方法:

您不会完全摆脱嵌套。接受艾伦的回答并稍微修改一下，这就是我想出的。它涉及通过几种方法传递一个 block 。

def self.populateProjectsTable(projects_controller) 
  @taskList = TaskList.new 
  @taskList.loginAndGetProjects do |projects| 
    projects_controller.projects = projects 
    projects_controller.reloadData 
  end 
end 
 
def loginAndGetProjects(&block) 
  payload = {email: "email", password: "pass"} 
  HTTP.post("http://example.com/login", {payload: payload}) do |response| 
    @authCookie = response.headers['Set-Cookie'] 
    getProjects(&block) 
  end 
end 
 
def getProjects(&block) 
  HTTP.get("http://example.com/projects.json", {cookie: @authCookie}) do |response| 
    projects = JSON.parse(response.body.to_str) 
    block.call(projects) 
  end 
end