Example.rb

# Example of the implementation

class Template
  module CompileSite; end

  def compile(klass, name, source)
    klass.class_eval <<-RUBY
      lambda {}.binding.__send__ :eval, <<-RB
        def \#{name}(locals)
          \#{source}
        end
      RB
    RUBY
  end

end

module Helper
  A = "A"
end

class Scope
  include Template::CompileSite
  include Helper
  B = "B"
end

Template.new.compile(Scope, 'hello', <<-RUBY)
  if locals.nil?
    yield
  else
    [locals, A, B, yield, hello(nil) { 'Y2' }, yield].join(" ")
  end
RUBY

res = Scope.new.hello("L") { "Y1" }

if res == "L A B Y1 Y2 Y1"
  puts "YOU DID IT!"
else
  puts "Failed:", res
end