关于PHP通用返回值设置方法

<?php
define("return_val", "return array('code' => 0, 'msg' => '', 'data' => '');");

define("RETURN_SUCCESS",    0); 
define("RETURN_RUNTIME_ERR",  1); 
define("RETURN_FILE_NOT_EXIST", 2); 

class ReturnConf{
  public static function CommonReturn(){
    return eval(return_val);
  }  
}
?>

<?php
require_once("Return.conf.php");

function get_file_line($filename){
  $result = ReturnConf::CommonReturn();
  
  $cmd = "wc -l $filename | awk '{print $1}'";
  exec($cmd, $output, $code);
  if (RETURN_SUCCESS !== $code){
    $result['code'] = RETURN_RUNTIME_ERR;
    $result['msg'] = "exec $cmd err";
    return $result; 
  }  

  $result['data'] = $output[0];
  return $result;
}

print_r(get_file_line("test.php"));
?>