SplPriorityQueue::__construct()

(PHP 5 >= 5.3.0, PHP 7)

Constructs a new empty queue

说明

This constructs a new empty queue.

参数

此函数没有参数。

返回值

没有返回值。

I was trying to extend SplPriorityQueue like this:
<?php
class AdjustablePriorityQueue extends SplPriorityQueue {
  protected $direction='desc';//queue is ordered highest to lowest priority, direction is changeable ONLY on __construct()
  function __construct($direction='desc'){
    parent::__construct(); //Fatal error: Cannot call constructor
    $this->direction=($direction=='asc') ? 'asc': 'desc';
  }
  function compare($priority1,$priority2){
    if($this->direction=='asc') return parent::compare($priority2, $priority1);
    return parent::compare($priority1,$priority2);
  }
}
?>
calling `parent::__construct()` gives a fatal error " Cannot call constructor". If I leave out that call, everything works fine. This suggests that SplPriorityQueue does not actually have a `__construct()` method.