gistfile1.rb

# GC on Template finalize
class Template
  module CompiledTemplates; end

  def self.garbage_collect_compiled_method(object_id)
    CompiledTemplates.module_eval do
      remove_method Template.compiled_method(object_id)
    end
  end

  def self.compiled_method(object_id)
    "__tilt_template_#{object_id}"
  end

  def initialize(source)
    @source = source

    ObjectSpace.define_finalizer(self, self.class.method(:garbage_collect_compiled_method))
  end

  def compiled_method
    self.class.compiled_method(object_id)
  end

  def render(context, locals = {})
    unless CompiledTemplates.instance_methods.include?(compiled_method)
      CompiledTemplates.module_eval <<-RUBY
        def #{compiled_method}(locals)
          #{locals.map { |k, v| "#{k} = locals[:#{k}]" }.join("\n")}
          #{@source}
        end
      RUBY
    end

    # extend context with module if the compiled method is not present
    unless context.respond_to?(compiled_method)
      context.extend CompiledTemplates
    end

    context.send(compiled_method, locals)
  end
end


template = Template.new('"foo: #{foo}"')
template.render(self, :foo => "bar") # => "foo: bar"