SPL: The Missing Link in Development

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

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/

SPL Background

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

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;
}

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

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'));

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;
}

iterator_to_array

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

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.

SPL Classes

• ArrayObject
• SplFileInfo

ArrayObject

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

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

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

Observer Pattern (SPL)

• Great for applying hooks
• Exception Handling
• User Authentication

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

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'));


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

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

Iterator

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

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()

Countable
• Internal Counter
<?php
class loopy
{
public function count()
{
static $count = 0;
return $count++;
}

public function access()
{
$this->count();
// Method logic
}
}

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');
}
}

SPL Iterators

• ArrayIterator
• LimitIterator
• DirectoryIterator
• RecursiveDirectoryIterator
• GlobIterator

ArrayIterator

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

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 $object->key().' -> '.$object->current().' ';

/*** hop to the next array member ***/
$object->next();
}

// Using Foreach
$object = new ArrayIterator($array);
foreach($object as $key=>$value)
{
echo $key.' => '.$value.' ';
}

Example Source: http://www.phpro.org/tutorials/Introduction-to-SPL.html#6

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().' ';
}

DirectoryIterator

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

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.' ';
{ }
continue; }
} /*** if an exception is thrown, catch it here ***/
$listing[] = $dirEntry; catch(Exception $e)
} {
} echo 'No files Found! ';
closedir($hdl); }
foreach($listing as $my_file)
{
echo $my_file.' ';
}

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 . " ";
}

GlobIterator (5.3)

• Very Similar to DirectoryIterator
• Only use if you want to convert old glob
code into an iterator object
• returns SplFileInfo Objects

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

SplFixedArray

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

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

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";
// OUTPUT:
// c
// b
// a

Example Source: http://www.alberton.info/php_5.3_spl_data_structures.html

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');


// OUTPUT:
// a
// b
// c

Example Source: http://www.alberton.info/php_5.3_spl_data_structures.html

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

SplStack

• Method: push and pop
• LIFO

SplQueue

• Methods: enqueue and dequeue
• FIFO

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

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

SPL: The Missing Link in Development

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