Handlebars.rb

This uses therubyracer to bind to the actual JavaScript implementation of Handlebars.js so that you can use it from ruby.

Usage

Simple stuff

require 'handlebars'
handlebars = Handlebars::Context.new
template = handlebars.compile("{{say}} {{what}}")
template.call(:say => "Hey", :what => "Yuh!") #=> "Hey Yuh!"

functions as properties

template.call(:say => "Hey ", :what => lambda {|this| ("yo" * 2) + "!"}) #=> "Hey yoyo!"

Block Helpers:

Just like JavaScript, you can write block helpers with an {{else}} section. To print out a section twice if a condition is met:

handlebars.register_helper(:twice) do |context, condition, block|
  if condition
    "#{block.fn(context)}#{block.fn(context)}"
  else
    block.inverse(context)
  end
end
template = handlebars.compile("{{#twice foo}}Hurray!{{else}}Boo!{{/twice}}")
template.call(foo: true) #=> Hurray!Hurray!
template.call(foo: false) #=> Boo!

Safe Strings

By default, handlebars will escape strings that are returned by your block helpers. To mark a string as safe:

template = handlebars.compile("{{safe}}")
template.call(:safe => proc {Handlebars::SafeString.new("<pre>Totally Safe!<pre>")})

Partials

You can directly register partials

handlebars.register_partial("whoami", "I am {{who}}")
handlebars.compile("{{>whoami}}").call(:who => 'Legend') #=> I am Legend

Partials can also be dynamically looked up by defining a partial_missing behavior:

handlebars.partial_missing do |name|
  "unable to find >#{name}"
end
handlebars.compile("{{>missing}}").call #=> unable to find >missing

Missing partials can also be returned as a function:

count = 0
handlebars.partial_missing do |name|
  lambda do |this, context, options|
    count += 1
    "#{count} miss(es) when trying to look up a partial"
  end
end
t = handlebars.compile("{{>missing}}")
t.call #=> 1 miss(es) when trying to look up a partial
t.call #=> 2 miss(es) when tyring to look up a partial

Hack

git clone git@github.com:cowboyd/handlebars.rb.git #git it
cd handlebars.rb #go to it
git submodule update --init #pull down handlebars.js
rspec spec/ #test it