ruby-on-rails - Rails 中的 "respond_to do |x| .. end"是什么 Ruby 语言结构？

Question

我是 ruby​​ 和 rails 的新手。有人可以指出以下结构是什么吗？我在方法 (def) 中看到了 respond_to 结构。那么它是方法中的方法吗？我的意思是我试图理解这里的语言结构。

我确实了解它的功能，即以给定格式发送响应。

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @posts }
    end

Answer 1

语言构造是一个ruby block 。但是，如果您真的想了解 respond_to，这里有一篇博文提供了很好的概述

How does respond_to work?

The key thing to understand is that respond_to is a method attached toyour controllers superclass: ActionController, and we are passing inas an argument something called a block:

...

inside the respond_to method, we end up with a Proc that takes oneargument. This argument has the .xml and .html methods called on it.What do we pass into the Proc as an argument when we call it frominside respond_to? We pass in an instance of the Responder class.

So we end up calling .html and .xml on an instance of the responderclass as it is passed into the block (that’s been converted to a Proc)inside the respond_to method… Phew.