SplQueue::dequeue

(PHP 5 >= 5.3.0, PHP 7)

SplQueue::dequeue — Dequeues a node from the queue

Description

mixed SplQueue::dequeue ( void )

Dequeues value from the top of the queue.

Note:
SplQueue::dequeue() is an alias of SplDoublyLinkedList::shift().

Parameters

This function has no parameters.

Return Values

The value of the dequeued node.

User Contributed Notes

mark at bull-roarer dot com

2 years ago


I just thought this was a fun and interesting way for lining up method calls and then calling them back-to-back. Might be useful as a basis for a transactional execution class or something.

<?php
$q = new SplQueue();
$q->setIteratorMode(SplQueue::IT_MODE_DELETE);

$q->enqueue(array("FooBar", "foo"));
$q->enqueue(array("FooBar", "bar"));
$q->enqueue(array("FooBar", "msg", "Hi there!"));

foreach ($q as $task) {
  if (count($task) > 2) {
    list($class, $method, $args) = $task;
    $class::$method($args);
  } else {
    list($class, $method) = $task;
    $class::$method();
  }
}

class FooBar {
  public static function foo() { 
    echo "FooBar::foo() called.\n";
  }
  public static function bar() {
    echo "FooBar::bar() called.\n";
  }
  public static function msg($msg) {
    echo "$msg\n";
  }
}
?>

Results:
FooBar::foo() called.
FooBar::bar() called.
Hi there!

andresdzphp at php dot net

4 years ago


<?php
$q = new SplQueue();
$q->setIteratorMode(SplQueue::IT_MODE_DELETE);
$q->enqueue('item 1');
$q->enqueue('item 2');
$q->enqueue('item 3');

$q->dequeue();
$q->dequeue();

foreach ($q as $item) {
    echo $item;
}

//Result: item 3

$q->dequeue(); //Fatal error: Uncaught exception 'RuntimeException' 
              //with message 'Can't shift from an empty datastructure'
?>

xuecan at gmail dot com

6 years ago


If the queue is empty, dequeue() will raise an 'RuntimeException' with message 'Can't shift from an empty datastructure'.

mark at bull-roarer dot com

2 years ago


I just thought this was a fun and interesting way for lining up method calls and then calling them back-to-back. Might be useful as a basis for a transactional execution class or something.

<?php
$q = new SplQueue();
$q->setIteratorMode(SplQueue::IT_MODE_DELETE);

$q->enqueue(array("FooBar", "foo"));
$q->enqueue(array("FooBar", "bar"));
$q->enqueue(array("FooBar", "msg", "Hi there!"));

foreach ($q as $task) {
  if (count($task) > 2) {
    list($class, $method, $args) = $task;
    $class::$method($args);
  } else {
    list($class, $method) = $task;
    $class::$method();
  }
}

class FooBar {
  public static function foo() { 
    echo "FooBar::foo() called.\n";
  }
  public static function bar() {
    echo "FooBar::bar() called.\n";
  }
  public static function msg($msg) {
    echo "$msg\n";
  }
}
?>

Results:
FooBar::foo() called.
FooBar::bar() called.
Hi there!