think\Validate使用如何优雅使用多语言？

<?php

namespace app\validate\report;

use think\Validate;

class ReportDetailValidate extends Validate
{
    protected $failException = true;

    protected $rule = [
        'checkId'  => 'require|number'
    ];

    protected $message = [
        'checkId.require' => trans('checkId_require'),
        'checkId.number' => '检查报告ID是数字'
        ];
}

报错：
PHP Fatal error:  Constant expression contains invalid operations in ...