1. SPL: The Missing Link in Development
Jake Smith
Dallas PHP - 7/13/2010

2. What is SPL?
• A
library
of
standard
interfaces,
classes,
and
functions
designed
to
solve
common
programming
problems
and
allow
engine
overloading.
Definition Source: http://elizabethmariesmith.com/

3. SPL Background
• Provides Interfaces, Classes and Functions
• As of PHP 5.3 you can not turn off SPL
• Poor documentation root of poor
adoption.

4. SPL Autoloading

5. Before SPL Autoload
set_include_path(dirname(__FILE__) . '/lib' . PATH_SEPARATOR . get_include_path());
function __autoload($class_name) {
$path = dirname(__FILE__) . '/lib/' . str_replace('_', '/', strtolower
($class_name)) . '.php';
if (file_exists($path)) {
require $path;
} else {
die('Class ' . $path . ' Not Found');
}
}
Class Name
<?php
class Form_Element_Text extends Form_Element
{
public function __construct($name = '', $attrs = array())
{
$this->_name = $name;
$this->_attrs = $attrs;
}

6. Autoloading w/SPL
<?php
/*** nullify any existing autoloads ***/
spl_autoload_register(null, false);
/*** specify extensions that may be loaded ***/
spl_autoload_extensions('.php, .class.php');
/*** class Loader ***/
function classLoader($class)
{
$filename = strtolower($class) . '.class.php';
$file ='classes/' . $filename;
if (!file_exists($file))
{
return false;
}
include $file;
}
/*** register the loader functions ***/
spl_autoload_register('classLoader');
Example Source: http://www.phpro.org/tutorials/SPL-Autoload.html

7. Multiple Autoloaders
<?php
/*** nullify any existing autoloads ***/
spl_autoload_register(null, false);
spl_autoload_register(array('Doctrine_Core', 'autoload'));
spl_autoload_register(array('Doctrine_Core', 'modelsAutoload'));

8. Multiple Autoloaders
<?php
class Doctrine_Core
{
public static function autoload($className)
{
if (strpos($className, 'sfYaml') === 0) {
require dirname(__FILE__) . '/Parser/sfYaml/' . $className . '.php';
return true;
}
if (0 !== stripos($className, 'Doctrine_') || class_exists($className, false) || interface_exists($className, false)) {
return false;
}
$class = self::getPath() . DIRECTORY_SEPARATOR . str_replace('_', DIRECTORY_SEPARATOR, $className) . '.php';
if (file_exists($class)) {
require $class;
return true;
}
return false;
}

9. SPL Functions

10. iterator_to_array
• Takes an iterator object, an object that
implements Traversable
• All iterators implement Traversable

11. spl_object_hash
• MD5 hash of internal pointer
• When objects are destroyed their object
hash is released
• Object Hash ID can/will be reused after
destruction.

12. SPL Classes
• ArrayObject
• SplFileInfo

13. ArrayObject
• Allows objects to act like arrays
• Does not allow usage of array functions on
object
• Built in methods: ksort, usort, asort,
getArrayCopy

14. SplFileInfo
• Object that returns information on Files/
Folders
• isDir, isFile, isReadable, isWritable, getPerms
(returns int), etc.
Example Source: http://us3.php.net/manual/en/class.splfileinfo.php

15. SPL Interfaces
• ArrayAccess
• Iterator
• RecursiveIterator
• Countable
• SeekableIterator
• SplSubject/SplObserver

16. Observer Pattern (SPL)
• Great for applying hooks
• Exception Handling
• User Authentication

17. SplSubject
<?php
class ExceptionHandler implements SplSubject
{
private $_observers = array();
public function attach(SplObserver $observer)
{
$id = spl_object_hash($observer);
$this->_observers[$id] = $observer;
}
public function detach(SplObserver $observer)
{
$id = spl_object_hash($observer);
unset($this->_observers[$id]);
}
public function notify()
{
foreach($this->_observers as $obs) {
$obs->update($this);
}
}
public function handle(Exception $e)
{
$this->exception = $e;
$this->notify();
}
}
Example Source: http://devzone.zend.com/article/12229

18. SplObserver
Class Mailer implements SplObserver {
public function update(SplSubject $subject)
{
// Do something with subject object
}
}
// Create the ExceptionHandler
$handler = new ExceptionHandler();
// Attach an Exception Logger and Mailer
$handler->attach(new Mailer());
// Set ExceptionHandler::handle() as the default
set_exception_handler(array($handler, 'handle'));
Example Source: http://devzone.zend.com/article/12229

19. ArrayAccess
• OffsetExists - Values exists for key, returns
boolean
• OffsetSet - Set value for key
• OffsetGet - Return value for key
• OffsetUnset - Remove value from array
• Note that if the array is numerically indexed, a call to array_values() will be required to re-index
the array if that is the behaviour required.
Example Source: http://www.phpro.org/tutorials/Introduction-to-SPL-ArrayAccess.html

20. ArrayAccess Example
<?php
class book implements ArrayAccess
{
public $title;
public $author;
public $isbn;
public function offsetExists( $offset )
{
return isset( $this->$offset );
}
public function offsetSet( $offset, $value)
{
$this->$offset = $value;
}
public function offsetGet( $offset )
{
return $this->$offset;
}
public function offsetUnset( $offset )
{
unset( $this->$offset );
}
}
Example Source: http://www.phpro.org/tutorials/Introduction-to-SPL-ArrayAccess.html

21. Iterator
• Provides basic iterator functionality
(foreach)
• Interface requires the following methods
• current(), key(), next(), rewind(), valid()

22. Recursive Iterator
• A foreach only goes top level, but many
times you need to dig deeper
• Recursive Iterator extends Iterator and
requires hasChildren() and getChildren()

23. Countable
• Internal Counter
<?php
class loopy
{
public function count()
{
static $count = 0;
return $count++;
}
public function access()
{
$this->count();
// Method logic
}
}

24. SeekableIterator
• Other iterators must start at beginning of
an array, but seekable allows you to change
iteration start point.
<?php
class PartyMemberIterator implements SeekableIterator
{
public function seek($index)
{
$this->rewind();
$position = 0;
while ($position < $index && $this->valid()) {
$this->next();
$position++;
}
if (!$this->valid()) {
throw new OutOfBoundsException('Invalid position');
}
}
Example Source: http://devzone.zend.com/article/2565

25. SPL Iterators
• ArrayIterator
• LimitIterator
• DirectoryIterator
• RecursiveDirectoryIterator
• GlobIterator

26. ArrayIterator
• Implements: Iterator, Traversable,
ArrayAccess, SeekableIterator, Countable
• Used to Iterate over ArrayObject or PHP
array

27. ArrayIterator
<?php
// Using While
/*** create a new object ***/
$object = new ArrayIterator($array);
/*** rewind to the beginning of the array ***/
$object->rewind();
/*** check for valid member ***/
while($object->valid())
{
/*** echo the key and current value ***/
echo $object->key().' -&gt; '.$object->current().'<br />';
/*** hop to the next array member ***/
$object->next();
}
// Using Foreach
$object = new ArrayIterator($array);
foreach($object as $key=>$value)
{
echo $key.' => '.$value.'<br />';
}
Example Source: http://www.phpro.org/tutorials/Introduction-to-SPL.html#6

28. LimitIterator
• Used similar to Limit in SQL
<?php
// Show 10 files/folders starting from the 3rd.
$offset = 3;
$limit = 10;
$filepath = '/var/www/vhosts/mysite/images'
$it = new LimitIterator(new DirectoryIterator($filepath), $offset, $limit);
foreach($it as $r)
{
// output the key and current array value
echo $it->key().' -- '.$it->current().'<br />';
}

29. DirectoryIterator
• If you’re accessing the filesystem this is the
iterator for you!
• Returns SplFileInfo object

30. DirectoryIterator
<?php <?php
$hdl = opendir('./'); try
while ($dirEntry = readdir($hdl)) {
{ /*** class create new DirectoryIterator Object ***/
if (substr($dirEntry, 0, 1) != '.') foreach ( new DirectoryIterator('./') as $Item )
{ {
if(!is_file($dirEntry)) echo $Item.'<br />';
{ }
continue; }
} /*** if an exception is thrown, catch it here ***/
$listing[] = $dirEntry; catch(Exception $e)
} {
} echo 'No files Found!<br />';
closedir($hdl); }
foreach($listing as $my_file)
{
echo $my_file.'<br />';
}

31. RecursiveDirectory
Iterator
• Move out of the top level and get all
children files/folders
<?php
$dir = '/Users/jsmith/Sites/vhosts/test.local/wwwroot';
$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir));
// could use CHILD_FIRST if you so wish
foreach ($iterator as $file) {
echo $file . "<br />";
}

32. GlobIterator (5.3)
• Very Similar to DirectoryIterator
• Only use if you want to convert old glob
code into an iterator object
• returns SplFileInfo Objects

33. SPL Exceptions
• Logic Exception
• RuntimeException
• BadFunction
• OutOfBounds
• BadMethodCall
• Range
• InvalidArgument
• UnexpectedValue
• OutOfRange
• Underflow
Example Source: http://www.php.net/manual/en/spl.exceptions.php

34. New SPL in PHP 5.3

35. SplFixedArray
• Array with pre-defined dimensions
• Shows great speed for setting and
retrieving
• If you change Array dimensions, it will
crawl.

36. SplHeap
• Automatically reorder after insert, based
off of compare() method
• Extract is similar to array_shift()
• Great memory usage!
Example Source: http://www.slideshare.net/tobias382/new-spl-features-in-php-53

37. SplMaxHeap
• Subclass of SplHeap
• When you extract() a value it will return in
order from greatest to least
<?php
$heap = new SplMaxHeap();
$heap->insert('b');
$heap->insert('a');
$heap->insert('c');
echo $heap->extract()."n";
echo $heap->extract()."n";
echo $heap->extract()."n";
// OUTPUT:
// c
// b
// a
Example Source: http://www.alberton.info/php_5.3_spl_data_structures.html

38. SplMinHeap
• Subclass of SplHeap
• When you extract() a value it will return in
order from least to greatest
<?php
$heap = new SplMinHeap();
$heap->insert('b');
$heap->insert('a');
$heap->insert('c');
echo $heap->extract()."n";
echo $heap->extract()."n";
echo $heap->extract()."n";
// OUTPUT:
// a
// b
// c
Example Source: http://www.alberton.info/php_5.3_spl_data_structures.html

39. SplDoublyLinkedList
• Do not know size of list/array
• Can only be read sequentially
• Less processing power required, on large
data sets provides better memory usage

40. SplStack
• Method: push and pop
• LIFO

41. SplQueue
• Methods: enqueue and dequeue
• FIFO

42. Questions?

43. Useful Links
• SPL in 5.3
• http://www.alberton.info/
php_5.3_spl_data_structures.html
• http://www.slideshare.net/tobias382/new-spl-features-in-
php-53
• Intro to SPL
• http://www.phpro.org/tutorials/Introduction-to-SPL.html
• http://www.slideshare.net/DragonBe/spl-not-a-bridge-too-
far

44. Thanks for listening!
Contact Information
[t]: @jakefolio
[e]: jake@dallasphp.org
[w]: http://www.jakefolio.com
[irc]: #dallasphp