Module | ActionView::Helpers::CaptureHelper
In: | lib/action_view/helpers/capture_helper.rb

Capture lets you extract parts of code which can be used in other points of the template or even layout file.

## Capturing a block into an instance variable

      <% @script = capture do %>
        [some html...]
      <% end %>

## Add javascript to header using content_for

content_for("name") is a wrapper for capture which will make the fragment available by name to a yielding layout or template.

layout.rhtml:

      <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
      <head>
          <title>layout with js</title>
          <script type="text/javascript">
            <%= yield :script %>
        </script>
      </head>
      <body>
        <%= yield %>
      </body>
      </html>

view.rhtml

      This page shows an alert box!

      <% content_for("script") do %>
        alert('hello world')
      <% end %>

      Normal view text

### Methods

capture content_for

### Public Instance methods

capture(*args, &block)

Capture allows you to extract a part of the template into an instance variable. You can use this instance variable anywhere in your templates and even in your layout.

Example of capture being used in a .rhtml page:

      <% @greeting = capture do %>
        Welcome To my shiny new web page!
      <% end %>

Example of capture being used in a .rxml page:

      @greeting = capture do
        'Welcome To my shiny new web page!'
      end

content_for(name, content = nil, &block)

Calling content_for stores the block of markup for later use. Subsequently, you can make calls to it by name with `yield` in another template or in the layout.

Example:

      <% content_for("header") do %>
        alert('hello world')
      <% end %>

You can use yield :header anywhere in your templates.

      <%= yield :header %>

NOTE: Beware that content_for is ignored in caches. So you shouldn‘t use it for elements that are going to be fragment cached.

The deprecated way of accessing a content_for block was to use a instance variable named @@content_for_#{name_of_the_content_block}@. So `<%= content_for(‘footer’) %>` would be avaiable as `<%= @content_for_footer %>`. The preferred notation now is `<%= yield :footer %>`.

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