class Tilt::ERBTemplate

def evaluate(scope, locals, &block)
  source, offset = local_assignment_code(locals)
  source = [source, template_source].join("\n")
  original_out_buf =
    scope.instance_variables.any? { |var| var.to_sym == :@_out_buf } &&
    scope.instance_variable_get(:@_out_buf)
  scope.instance_eval source, eval_file, line - offset
  output = scope.instance_variable_get(:@_out_buf)
  scope.instance_variable_set(:@_out_buf, original_out_buf)
  output
end