编写一个检查访问权限并返回更多布尔值的PHP函数的最佳模式？

I'm prototyping behaviour of a new application, and want to write some functions that check on access based on some variable dates.

I just want to write seperate functions for that, like "canUserSeeThis()" and "canUserSeeThat()"

In case one of these returns false, I want to display a message, but I want that message to be defined in these functions, but the rendering taking part outside the functions.

What is the best "pattern" to quickly build such a functionality? Should I let the message be in the return value? Should I work with throwing exceptions?

I'm just prototyping, so I don't want to end up defining a complete API system yet.

I think that just passing by reference is what you need:

<?php
  function canUserSeeThis(&$whyCanNotMessage)
  {
    $whyCanNotMessage = 'Because you are not administrator';
    return false;
  }

  $meesage;
  if (!canUserSeeThis($meesage))
  print($message);
?>

If you need to gather several messages you could pass by reference an array and every canUserSeeXXX() method will add a string to the array. Later you print all array items to the user.

<?php
  function canUserSeeThis(&$whyCanNotMessageList)
  {
    array_push($whyCanNotMessageList, 'Because you are not administrator');
    return false;
  }

   function canUserSeeThat(&$whyCanNotMessageList)
  {
    array_push($whyCanNotMessageList, 'Because you are not advanced user');
    return false;
  }

  $meesageList = array();
  $shouldShowMessage = !canUserSeeThis($meesageList)||!canUserSeeThat($meesageList);

  if ($shouldShowMessage)
  echo '<pre>'; print_r($meesageList); echo '</pre>';
?>