SPL: The Missing Link in Development

The Standard PHP Library (SPL) is the php extension that so many developers pass on out of lack of knowledge, NO MORE! Jake Smith will introduce you to the benefits of utilizing SPL features (iterators, interfaces, exceptions and autoloader). Also, continuing from last months talk he will introduce some new PHP 5.3 SPL classes.

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 ' . $path . ' Not Found'); } } <?php class Form_Element_Text extends Form_Element { public function __construct($name = '', $attrs = array()) { $this->_name = $name; $this->_attrs = $attrs; } Class Name
6. Autoloading w/SPL <?php /*** nullify any existing autoloads ***/ spl_autoload_register(null, false); /*** specify extensions that may be loaded ***/ spl_autoload_extensions('.php, .class.php'); /*** class Loader ***/ function classLoader($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 $hdl = opendir('./'); while ($dirEntry = readdir($hdl)) { if (substr($dirEntry, 0, 1) != '.') { if(!is_file($dirEntry)) { continue; } $listing[] = $dirEntry; } } closedir($hdl); foreach($listing as $my_file) { echo $my_file.'<br />'; } <?php try { /*** class create new DirectoryIterator Object ***/ foreach ( new DirectoryIterator('./') as $Item ) { echo $Item.'<br />'; } } /*** if an exception is thrown, catch it here ***/ catch(Exception $e) { echo 'No files Found!<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 • BadFunction • BadMethodCall • InvalidArgument • OutOfRange • RuntimeException • OutOfBounds • Range • UnexpectedValue • 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