SPL, not a bridge too far
phpNW 2009 - Manchester

Who am I ?
Michelangelo van Dam
Independent Enterprise PHP consultant
Co-founder PHPBenelux UG
@dragonbe
http://dragonbe.com
2

Who are you ?
Are you familiar with php.net ?
Are you familiar with arrays ?
Are you familiar with OOP ?
Are you familiar with Design Patterns ?
3

What is SPL ?
Standard PHP Library
interfaces, classes and methods
solve common development challenges
Available since PHP 5.0 !!!
As of 5.3 SPL cannot be turned off from the source !
4

SPL by Marcus Börger
Ittteerrrattor
5

Definition of SPL
SPL provides a huge toolkit that assists you to easily
iterate over a diversity of data structures in a
standardized way
6

What does it provide ?
• ArrayObject - approach arrays as objects
• Iterators - various iterators
• Interfaces - iterator interfaces for your objects
• Exceptions - exceptions to streamline error handling
• SPL Functions - extra functions and autoloader func
• SplFileInfo - tools for filesystem access
• Data structures - structuring data sequences
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<?php phpinfo(); ?>
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ArrayObject
• provides an interface
- treat arrays as objects
- elements are iteratable
- provides serializing and deserializing of arrays
- sorting elements (w/ or w/o callback methods)
- exchange elements with other arrays or objects
9

<?php
ArrayObject Example
$myArray = array (
'time' => 'Derick Rethans',
'test' => 'Sebastian Bergmann',
'iterate' => 'Marcus Börger',
);
$obj = new ArrayObject($myArray);
print_r($obj);
$obj->uasort(function ($a, $b) {
if ($a == $b) {
return 0;
}
return ($a < $b) ? -1 : 1;
});
print_r($obj);
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ArrayObject output
ArrayObject Object
(
[storage:ArrayObject:private] => Array
(
[time] => Derick Rethans
[test] => Sebastian Bergmann
[iterate] => Marcus Börger
)
)
ArrayObject Object
(
[storage:ArrayObject:private] => Array
(
[time] => Derick Rethans
[iterate] => Marcus Börger
[test] => Sebastian Bergmann
)
)
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…
More of ArrayObject
// serializing object for caching, sessions, …
$obj->serialize();
// adding more key/value elements to the stack
$obj->offsetSet('enterprise', 'Ivo Jansch');
// removing by key
$obj->offsetUnset('time');
…
12

Iterator
• provides a common interface
• to iterate over “things”
- xml data
- database data
- arrays
• move back and forth in a stack
• distinct methods to access keys and values
• specific iterators for different purposes
13

Advantage ?
• Reusable code
- data structures can change
- object oriented
✓ extending
✓ refactoring
✓ overloading
14

Example
• retrieve data in an array
• with items filtered out
15

<?php
FilterIterator Example
class filterOut extends FilterIterator
{
private $_filter;
public function __construct(Iterator $it, $filter)
{
parent::__construct($it);
$this->_filter = $filter;
}
public function accept()
{
$key = $this->getInnerIterator()->key();
return ($key == $this->_filter) ? false : true;
}
}
16

<?php
FilterIterator output
$myArray = array (
'time' => 'Derick Rethans',
'test' => 'Sebastian Bergmann',
'iterate' => 'Marcus Börger',
);
$obj = new ArrayObject($myArray);
$iterator = new filterOut($obj->getIterator(), 'time');
foreach ($iterator as $item) {
var_dump($item);
}
//ouputs
string(18) "Sebastian Bergmann"
string(13) "Marcus Börger"
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DirectoryIterator
• dealing with files and directories
• looping back and forth between files
• sorting files w/ or w/o custom sorting algorithms
18

Example
• show an list of archive files
• ordered with last archive first
19

Directory contents
$ ls archives/
datafile-20090901.csv datafile-20090906.csv
datafile-20090911.csv datafile-20090916.csv
datafile-20090921.csv datafile-20090926.csv
datafile-20090902.csv datafile-20090907.csv
datafile-20090912.csv datafile-20090917.csv
datafile-20090922.csv datafile-20090927.csv
datafile-20090903.csv datafile-20090908.csv
datafile-20090913.csv datafile-20090918.csv
datafile-20090923.csv datafile-20090928.csv
datafile-20090904.csv datafile-20090909.csv
datafile-20090914.csv datafile-20090919.csv
datafile-20090924.csv datafile-20090929.csv
datafile-20090905.csv datafile-20090910.csv
datafile-20090915.csv datafile-20090920.csv
datafile-20090925.csv datafile-20090930.csv
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SortableDirectorIterator
<?php
class SortableDirectoryIterator extends DirectoryIterator
{
public function sortUp()
{
$storage = $this->_getStorage();
$storage->uksort(function ($a, $b) {
if ($a == $b) return 0;
return ($a < $b) ? -1 : 1;
});
return $storage;
}
public function sortDown()
{
$storage = $this->_getStorage();
$storage->uksort(function ($a, $b) {
if ($a == $b) return 0;
return ($a < $b) ? 1 : -1;
});
return $storage;
}
21

…
Our Storage Container
protected function _getStorage()
{
$obj = new ArrayObject();
foreach ($this as $file) {
if ($file->isDot()) continue;
$obj->offsetSet($file->getFileName(),
$file->getFileInfo());
}
return $obj;
}
}
$dir = new SortableDirectoryIterator('./archives');
$sortObj = $dir->sortDown();
$iterator = $sortObj->getIterator();
while ($iterator->valid()) {
echo $iterator->current()->getPathName() . PHP_EOL;
$iterator->next();
}
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Voila ! Descending filenames
./archives/datafile-20090930.csv ./archives/datafile-20090915.csv
./archives/datafile-20090929.csv ./archives/datafile-20090914.csv
./archives/datafile-20090928.csv ./archives/datafile-20090913.csv
./archives/datafile-20090927.csv ./archives/datafile-20090912.csv
./archives/datafile-20090926.csv ./archives/datafile-20090911.csv
./archives/datafile-20090925.csv ./archives/datafile-20090910.csv
./archives/datafile-20090924.csv ./archives/datafile-20090909.csv
./archives/datafile-20090923.csv ./archives/datafile-20090908.csv
./archives/datafile-20090922.csv ./archives/datafile-20090907.csv
./archives/datafile-20090921.csv ./archives/datafile-20090906.csv
./archives/datafile-20090920.csv ./archives/datafile-20090905.csv
./archives/datafile-20090919.csv ./archives/datafile-20090904.csv
./archives/datafile-20090918.csv ./archives/datafile-20090903.csv
./archives/datafile-20090917.csv ./archives/datafile-20090902.csv
./archives/datafile-20090916.csv ./archives/datafile-20090901.csv
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RecursiveIteratorIterator
• iterates over existing iterator
• over multiple levels
• easy to flatten out nested array structures
• controlling recursive interactions
24

Example
Chuck Norris
Account Manager
Jane Doe John Doe
Project Manager Project Manager
Cinderella Shrek
Developer Graphical Designer
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RecursiveIteratorIterator
<?php
$company = array (
array (
'name' => 'Chuck Norris','position' => 'Account Manager',
'manages' => array (
array (
'name' => 'Jane Doe','position' => 'Project Manager',
'manages' => array (
array (
'name' => 'Cinderella','position' => 'Developer',
'manages' => array (),
),
array (
'name' => 'Shrek','position' => 'Graphical Designer',
'manages' => array (),
),
),
),
array (
'name' => 'John Doe','position' => 'Project Manager',
'manages' => array (),
),
),
),
);
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Flattened Array output
$iterator = new RecursiveArrayIterator(new ArrayObject($company));
$ritit = new RecursiveIteratorIterator($iterator);
foreach ($ritit as $key => $value) {
echo $key . ' = ' . $value . PHP_EOL;
}
// outputs
name = Chuck Norris
position = Account Manager
name = Jane Doe
position = Project Manager
name = Cinderella
position = Developer
name = Shrek
position = Graphical Designer
name = John Doe
position = Project Manager
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Interfaces
• Countable: an internal counter
• OuterIterator: iteration over inner iterators
• RecursiveIterator: iterating in an recursive way
• SeekableIterator: an internal stack seeker
• SplObserver: implements observer pattern
• SplSubject: implements observer pattern
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<?php
Interface example
// file: Order.php
class Order implements Countable, SplSubject
{
protected $_orders;
protected $_count;
public function __construct()
{
$this->_count = 0;
$this->_orders = array ();
}
public function placeOrder()
{
$this->_count++;
}
public function attach(SplObserver $observer)
{
$this->_orders[] = $observer;
}
public function detach(SplObserver $observer)
{
// not used in this case
}
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Interface Example (2)
public function notify()
{
foreach ($this->_orders as $obj) {
$obj->update($this);
}
}
public function count()
{
return $this->_count;
}
}
<?php
// file: PlaceOrder.php
class PlaceOrder implements SplObserver
{
public function update(SplSubject $order)
{
echo 'We have ' . count($order) . ' orders now' . PHP_EOL;
}
}
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Running Interface Example
<?php
require_once 'Order.php';
require_once 'PlaceOrder.php';
$order = new Order();
$placeOrder = new PlaceOrder();
$order->attach($placeOrder);
$order->notify();
$order->placeOrder();
$order->notify();
$order->placeOrder();
$order->notify();
$ php ./spl_observer.php
We have 0 orders now
We have 1 orders now
We have 2 orders now
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SPL Exceptions
• SPL Exceptions
- templates
- throw exceptions
- common issues
• Types of exceptions
- LogicExceptions
- RuntimeExceptions
32

SPL LogicException Tree
33

SPL RuntimeException Tree
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<?php
Exceptions Example
//file: spl_exception01.php
class MyClass
{
public function giveANumberFromOneToTen($number)
{
if($number < 1 || $number > 10) {
throw new OutOfBoundsException('Number should be between 1 and 10');
}
echo $number . PHP_EOL;
}
}
$my = new MyClass();
try {
$my->giveANumberFromOneToTen(5);
$my->giveANumberFromOneToTen(20);
} catch (OutOfBoundsException $e) {
echo $e->getMessage() . PHP_EOL;
}
Output:
$ /usr/bin/php ./spl_exception01.php
5
Number should be between 1 and 10
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SplFunctions
• functions for PHP and SPL in particular
• often dealing with auto loading
• some for internal referencing
36

<?php
SplFunctions Example
interface foo {}
interface bar {}
class baz implements foo, bar {}
class example extends baz {}
var_dump(class_implements(new baz));
var_dump(class_implements(new example));
37

Output of SplFunctions
array(2) {
["foo"]=>
string(3) "foo"
["bar"]=>
string(3) "bar"
}
array(2) {
["bar"]=>
string(3) "bar"
["foo"]=>
string(3) "foo"
}
38

SPLFileInfo
The SplFileInfo class offers a high-level object oriented
interface to information for an individual file.
39

<?php
SplFileInfo Example
// use the current file to get information from
$file = new SplFileInfo(dirname(__FILE__));
var_dump($file->isFile());
var_dump($file->getMTime());
var_dump($file->getSize());
var_dump($file->getFileInfo());
var_dump($file->getOwner());
//output
bool(false)
int(1244760945)
int(408)
object(SplFileInfo)#2 (0) {
}
int(501)
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Processing CSV with SPL
Consider the following data.csv
Derick Rethans;time
Sebastian Bergmann;test
Marcus Börger;iterate
Ivo Jansch;enterprise
Matthew Weier O'Phinney;extend
Michelangelo van Dam;elephpant
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<?php
SPL usage on CSV
$info = new SplFileInfo('data.csv');
if ($info->isReadable()) {
$file = $info->openFile();
$file->setFlags(SplFileObject::READ_CSV);
$file->setCsvControl(';','"');
foreach ($file as $row) {
list ($user, $term) = $row;
if (null !== $user && null !== $term) {
echo $user . ' is known for ' . $term . PHP_EOL;
}
}
}
//outputs
Derick Rethans is known for time
Sebastian Bergmann is known for test
Marcus Börger is known for iterate
Ivo Jansch is known for enterprise
Matthew Weier O'Phinney is known for extend
Michelangelo van Dam is known for elephpant
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Data Structures
• Available in PHP 5.3.x
- SplDoublyLinkedList
✓ SplStack
✓ SplQueue
✓ SplHeap
✓ SplMaxHeap
✓ SplMinHeap
✓ SplPriorityQueue
43

Data Structures Example
<?php
// file: spl_stack01.php
$stack = new SplStack();
$stack->push('Message 1');
$stack->push('Message 2');
$stack->push('Message 3');
echo $stack->pop() . PHP_EOL;
echo $stack->pop() . PHP_EOL;
echo $stack->pop() . PHP_EOL;
Outputs:
$ /usr/bin/php ./spl_stack01.php
Message 3
Message 2
Message 1
44

SplHeap
• SplHeap is an abstract class
- SplMinHeap implements SplHeap (low » high)
- SplMaxHeap implements SplHeap (high » low)
• stacking values w/o FIFO, FILO order
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Simple SplHeap example
<?php
$heap = new SplMinHeap;
$heap->insert(5);
$heap->insert(2);
$heap->insert(8);
$heap->insert(6);
$heap->top();
while ($heap->valid()) {
echo $heap->key() . ': ' . $heap->current() . PHP_EOL;
$heap->next();
}
//outputs
3: 2
2: 5
1: 6
0: 8
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JupilerLeague with SplHeap
<?php
class JupilerLeague extends SplHeap
{
public function compare($array1, $array2)
{
$values1 = array_values($array1);
$values2 = array_values($array2);
if ($values1[0] === $values2[0]) return 0;
return $values1[0] < $values2[0] ? -1 : 1;
}
}
$heap = new JupilerLeague();
$heap->insert(array ('AA Gent' => 15)); $heap->insert(array ('Anderlecht' => 20));
$heap->insert(array ('Cercle Brugge' => 11)); $heap->insert(array ('Charleroi' => 12));
$heap->insert(array ('Club Brugge' => 21)); $heap->insert(array ('G. Beerschot' => 15));
$heap->insert(array ('Kortrijk' => 10)); $heap->insert(array ('KV Mechelen' => 18));
$heap->insert(array ('Lokeren' => 10)); $heap->insert(array ('Moeskroen' => 7));
$heap->insert(array ('Racing Genk' => 11)); $heap->insert(array ('Roeselare' => 6));
$heap->insert(array ('Standard' => 20)); $heap->insert(array ('STVV' => 17));
$heap->insert(array ('Westerlo' => 10)); $heap->insert(array ('Zulte Waregem' => 15));
$heap->top();
while ($heap->valid()) {
list ($team, $score) = each ($heap->current());
echo $team . ': ' . $score . PHP_EOL;
$heap->next();
}
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JupilerLeague Scoreboard
Club Brugge: 21
Anderlecht: 20
Standard: 20
KV Mechelen: 18
STVV: 17
Zulte Waregem: 15
AA Gent: 15
G. Beerschot: 15
Charleroi: 12
Racing Genk: 11
Cercle Brugge: 11
Kortrijk: 10
Lokeren: 10
Westerlo: 10
Moeskroen: 7
Roeselare: 6
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Conclusion
SPL can help you solve common PHP issues
it’s built-in, so why not use it
it requires no “advanced skills” to use
49

SPL is not all good
• Matthew “Elazar” Turland pointed out:
- Performance could be better (SPLStack)
- ArrayObject doesn’t support all array
functions
• See his presentation:
http://ishouldbecoding.com/publications
50

Not a bridge too far...
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Only one minor thing...
52

Documentation problem
• php.net/spl needs more documentation !
• you can help on that part:
- see http://elizabethmariesmith.com/2009/02/setting-up-phd-on-windows
- you can set up phpdoc on each platform !
- Efnet: #php.doc channel
- http://doc.php.net - phpdoc@php.net
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More about SPL...
• main SPL documentation:
http://php.net/spl
• PHPro Tutorials on SPL:
http://www.phpro.org/tutorials/Introduction-to-SPL.html
• Lorenzo Alberton’s blog:
http://www.alberton.info/php_5.3_spl_data_structures.html
• http://www.colder.ch/news/01-08-2009/34/splobjectstorage-for-
a-fa.html
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License
This presentation is released under the Creative Commons
Attribution-Share Alike 3.0 Unported License
You are free:
- to share : to copy, distribute and transmit the work
- to remix : to adapt the work
Under the following conditions:
- attribution : You must attribute the work in the manner specified by the author or licensor
- share alike : If you alter, transform, or build upon this work, you may distribute the resulting work
only under the same, similar or a compatible license
See: http://creativecommons.org/licenses/by-sa/3.0/
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Photo credits
Marcus Boerger - Sebastian Bergmann
http://www.flickr.com/photos/sebastian_bergmann/173891817
Golden Gate Bridge - Felix De Vliegher
http://www.flickr.com/photos/felixdv/2883471022/
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Thank you
Find my slides on
http://slideshare.net/DragonBe
Don’t forget to vote !
http://joind.in/613
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