ContentFor

Small extension for the Sinatra web framework that allows you to use the following helpers in your views:

<% content_for :some_key do %>
  <chunk of="html">...</chunk>
<% end %>

<% yield_content :some_key %>

This allows you to capture blocks inside views to be rendered later in this request. For example, to populate different parts of your layout from your view.

When using this with the Haml rendering engine, you should do the following:

- content_for :some_key do
  %chunk{ :of => "html" } ...

= yield_content :some_key

Note that with ERB yield_content is called without an '=' block (<%= %>), but with Haml it uses = yield_content.

Using an '=' block in ERB will output the content twice for each block, so if you have problems with that, make sure to check for this.

Usage

If you're writing "classic" style apps, then requring sinatra/content_for should be enough. If you're writing "classy" apps, then you also need to call helpers Sinatra::ContentFor in your app definition.

And how is this useful?

For example, some of your views might need a few javascript tags and stylesheets, but you don't want to force this files in all your pages. Then you can put <% yield_content :scripts_and_styles %> on your layout, inside the tag, and each view can call content_for setting the appropriate set of tags that should be added to the layout.

How is this different from foca's version?

This code was based on foca's version, which supports passing block values to the content, which means lazy rendering of the blocks. This plays havoc with anything that assumes that views are rendered before layouts, such as setting instance variables and the fancyviews plugin.

Credits

Original code by foca, inspired on the Ruby on Rails helpers with the same name. Haml support by macodely. Modified by me (Tim Lucas) for the above reasons.