class IDL::Delegator

def parse_positive_int(_expression)
  if _expression.is_template?
    _expression
  else
    if not ::Integer === _expression.value
      raise "must be integer: #{_expression.value.inspect}"
    elsif _expression.value.negative?
      raise "must be positive integer: #{_expression.value}"
    elsif _expression.value.zero?
      raise "must be positive integer"
    end
    _expression.value
  end
end