test.rb

#!/usr/bin/env ruby
 
require 'erb'

class Bindable
  def get_binding
    return binding()
  end  
end

def render(str, hs)
  o = Bindable.new

  hs.each do |k, v|
    o.instance_variable_set("@#{k}".to_s, v)
  end
  
  ERB.new(str).result(o.get_binding)
end

Result = render("<%= @contents %>", {contents: "hello"})