SplQueue::dequeue()

(PHP 5 >= 5.3.0, PHP 7)

Dequeues a node from the queue

说明

SplQueue::dequeue(void) : mixed

Dequeues $value from the top of the queue.

Note:

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

参数

此函数没有参数。

返回值

The value of the dequeued node.

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

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!

<?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'
?>

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!