module ActionView::Helpers::CaptureHelper

<%= @greeting %>




You can then use that variable anywhere else. For example:

end
"The current timestamp is #{Time.now}."
@timestamp = capture do

...and Builder (RXML) templates.

<% end %>
<%= Time.now %>
Welcome to my shiny new web page! The date and time is
<% @greeting = capture do %>

The capture method can be used in ERb templates...
==== Examples

variable. You can then use this variable anywhere in your templates or layout.
The capture method allows you to extract part of a template into a

def capture(*args)
  value = nil
  buffer = with_output_buffer { value = yield(*args) }
  if string = buffer.presence || value and string.is_a?(String)
    NonConcattingString.new(ERB::Util.html_escape(string))
  end
end

for elements that will be fragment cached.
WARNING: content_for is ignored in caches. So you shouldn't use it

<% content_for :script, javascript_include_tag(:defaults) %>

Lastly, simple content can be passed as a parameter:

<%= content_for :navigation %>

Then, in another template or layout, this code would render both links in order:

<% end %>

<%= link_to 'Login', :action => 'login' %>

<% content_for :navigation do %>

<%# Add some other content, or use a different template: %>

<% end %>

<%= link_to 'Home', :action => 'index' %>

<% content_for :navigation do %>

identifier in order. For example:
Note that content_for concatenates the blocks it is given for a particular

on the page; this technique is useful if you'll only be using these scripts in a few views.
That will place script tags for Prototype, Scriptaculous, and application.js (if it exists)

<% end %>
<%= javascript_include_tag :defaults %>
<% content_for :script do %>

<%= link_to 'Logout', :action => 'logout', :remote => true %>

Then, in another view, you could to do something like this:

<% end %>

<% content_for :script do %>

Please login!
<%# This is our view %>

creates the script identifier.
And now, we'll create a view that has a content_for call that



<%= yield %>


<%= yield :script %>



<%# This is the layout %>

You can use the yield syntax alongside an existing call to yield in a layout. For example:

<%= stored_content %>

This helper works just like normal helpers.

end
end
content_for(:storage) || "Your storage is empty"
def stored_content
module StorageHelper

content_for, however, can also be used in helper modules.

<%= yield :not_authorized if current_user.nil? %>

This is equivalent to:

<%= content_for :not_authorized if current_user.nil? %>

You can then use content_for :not_authorized anywhere in your templates.

<% end %>
alert('You are not authorized to do that!')
<% content_for :not_authorized do %>

==== Examples

yield doesn't work in helper modules, while content_for does.
Note: yield can still be used to retrieve the stored content, but calling

or the layout by passing the identifier as an argument to content_for.
You can make subsequent calls to the stored content in other templates, helper modules
Calling content_for stores a block of markup in an identifier for later use.

def content_for(name, content = nil, &block)
  content = capture(&block) if block_given?
  @_content_for[name] << content if content
  @_content_for[name] unless content
end

<%= yield :right_col %>
<%= yield %>


<%= yield :script %>



<%# This is the layout %>

Perhaps you will use different css in you layout if no content_for :right_column

==== Examples

Useful to render parts of your layout differently based on what is in your views.
content_for? simply checks whether any content has been captured yet using content_for

def content_for?(name)
  @_content_for[name].present?
end

:nodoc:
Add the output buffer to the response body and start a new one.

def flush_output_buffer #:nodoc:
  if output_buffer && !output_buffer.empty?
    response.body_parts << output_buffer
    self.output_buffer = output_buffer.respond_to?(:clone_empty) ? output_buffer.clone_empty : output_buffer[0, 0]
    nil
  end
end

:nodoc:
Defaults to a new empty string.
Use an alternate output buffer for the duration of the block.

def with_output_buffer(buf = nil) #:nodoc:
  unless buf
    buf = ActionView::OutputBuffer.new
    buf.force_encoding(output_buffer.encoding) if output_buffer.respond_to?(:encoding) && buf.respond_to?(:force_encoding)
  end
  self.output_buffer, old_buffer = buf, output_buffer
  yield
  output_buffer
ensure
  self.output_buffer = old_buffer
end