Getting Ruby syntax straight

Question

I am trying to teach myself Ruby and Ruby on Rails. Can someone give me some quick pointers on this code from http://guides.rubyonrails.org/getting_started.html

<%= form_for(@post) do |f| %>
  <% if @post.errors.any? %>
    <div id="errorExplanation">
      <h2><%= pluralize(@post.errors.count, "error") %> prohibited
      this post from being saved:</h2>
      <ul>
      <% @post.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>
  <div class="field">
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </div>
  <div class="field">
    <%= f.label :content %><br />
    <%= f.text_area :content %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Questions:

Sometimes the code uses <% and sometimes uses <%=. When do I use either of these?
What exactly does @ mean in Ruby and when is is used?
Besides for the HTML, is all of Ruby code, or there some new code/syntax which Ruby on Rails introduces?

http://stackoverflow.com/questions/11247480/what-is-the-difference-between-and-in-ruby-on-rails — Michael Berkowski, Feb 19 '13 at 21:49
And http://stackoverflow.com/questions/14319347/variables-in-ruby-on-rails — Michael Berkowski, Feb 19 '13 at 21:50
all those questions are answered numerous times. do you mind using google or stackoverflow's search capabilities? — Iuri G., Feb 19 '13 at 21:50
These are all very general questions about basic rails functionality, so you're not likely to get a useful answer here. You just need to work your way through a few tutorials and read a few books on Ruby. Rails does introduce a lot of methods and classes, but aside from html, css, and javascript, the syntax is all Ruby. — Zach Kemp, Feb 19 '13 at 21:51

score 2 · Accepted Answer · answered Feb 19 '13 at 21:50

<%= outputs the result of the expression to the page. <% just evaluates it.
@ indicates an instance variable in a class. In Rails, it's also how you expose a controller variable to it's view.
Rails does not add any new syntax to Ruby, although there are some conventions which may look different from 'traditional' Ruby code.

Getting Ruby syntax straight

1 Answers1