ERB support for Cells using Erbse.


Add this line to your application's Gemfile:

gem 'cells-erb'

This will register Erbse::Engine with Tilt for .erb files.

And that's all you need to do.


Erbse is the next-generation implementation of ERB that comes with some nice new semantics and explicit code. It does not use instance variables for output buffering.

You should read its docs to learn what you can and can't do with Erbse.


The global #concat helper is not supported in Cells-ERB. Erbse uses local variables as output buffers, hence this global state helper does not work. Please use explicit string concatenation instead.

Instead of

concat (:p, "Good")
concat "Morning!"

you can do

(:p, "Good") + "Morning!"

Block Yielding

With Erbse, you can actually capture blocks, pass them to other cells and yield them. This will simply return whatever the block returns, no weird buffer magic will be happening in the background.


The capture implementation in Cells-ERB is literally a yield.

def capture(&block)

If you want to capture a block of code without outputting it, you need to use Erbse's <%@ %> tag.

<%@ content = capture do %>
  It's <%= Time.new %>'o clock.
<% end %>

The content variable will now contain the string <h1>Hi!</h1>\nIt's 23:37'o clock..

Use [email protected] as a mnemonic for the correct tag, should you need this mechanic. capture is usually a smell of bad view design and should be avoided.

HTML Escaping

Cells doesn't escape except when you tell it to do. However, you may run into problems when using Rails helpers. Internally, those helpers often blindly escape. This is not Cells' fault but a design flaw in Rails.

As a first step, try this and see if it helps.

class SongCell < Cell::ViewModel
  include ActionView::Helpers::FormHelper
  include Cell::Erb # include Erb _after_ AV helpers.

  # ..

If that doesn't work, read the docs.


This gem works with Tilt 1.4 and 2.0, and hence allows you to use it from Rails 3.2 upwards.