SPL, not a bridge too far
Dutch PHP Conference 2009 - Amsterdam

Who am I ?
Michelangelo van Dam
Independent Enterprise PHP consultant
@dragonbe
http://dragonbe.com
2

Who are you ?
You know OOP ?
You know php.net ?
You know arrays ?
3

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

Why use SPL ?
SPL provides a huge toolkit that assists you to easily
iterate over a diversity of data structures in a
standardized way
5

What does it provide ?
• ArrayObject - approach arrays as objects
• Iterators - various iterators
• Interfaces - Countable Interface
• Exceptions - exceptions to streamline errorhandling
• SPL Functions - extra functions and autoloader func
• SplFileInfo - tools for filesystem access
• Datastructures - structuring data sequences
6

ArrayObject
• provides an interface
- treat arrays as objects
- elements are iteratable
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ArrayObject methods
• ArrayObject::append
• ArrayObject::__construct
• ArrayObject::count
• ArrayObject::getIterator
• ArrayObject::offsetExists
• ArrayObject::offsetGet
• ArrayObject::offsetSet
• ArrayObject::offsetUnset
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<?php
ArrayObject w/o SPL
// file: nospl_arrayobject01.php
$myArray = array (
\"monkey\" => \"bananas\",
\"rabbit\" => \"carrots\",
\"ogre\" => \"onions\",
);
echo \"Ogres exists ? \"
. (key_exists('ogre', $myArray) ? \"Yes\" : \"No\") . \"\\n\";
echo \"Ogres equals \"
. $myArray['ogre'] . \"\\n\";
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<?php
ArrayObject Example
// file: spl_arrayobject01.php
$myArray = array (
\"monkey\" => \"bananas\",
\"rabbit\" => \"carrots\",
\"ogre\" => \"onions\",
);
// create an object of the array
$arrayObj = new ArrayObject($myArray);
echo \"Ogres exists ? \"
. ($arrayObj->offsetExists(\"ogre\") ? \"Yes\" : \"No\") . \"\\n\";
echo \"Ogres equals \"
. $arrayObj->offsetGet(\"ogre\") . \"\\n\";
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ArrayObject Output
$ /usr/bin/php ./nospl_arrayobject01.php
Ogres exists ? Yes
Ogres equals onions
Execution time: 0.00064299999999995 microseconds.
$ /usr/bin/php ./spl_arrayobject01.php
Ogres exists ? Yes
Ogres equals onions
Execution time: 0.00054399999999999 microseconds.
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Iterator
• move back and forth in a stack
• distinct methods to access keys and values
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Iterators
• ArrayIterator
• CachingIterator
• RecursiveCachingIterator
• DirectoryIterator
• RecursiveDirectoryIterator
• FilterIterator
• LimitIterator
• ParentIterator
• RecursiveIteratorIterator
13

The ArrayIterator
iteration methods on array objects
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ArrayIterator Example Case
• Array with 3 elements
- monkey => bananas,
- rabbit => carrots,
- ogre => onions
• display total elements
• display key/value pairs while looping
• display key/value pair for 2nd element
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<?php
ArrayIterator w/o SPL
// file: nospl_iterator01.php
$myArray = array (
\"monkey\" => \"bananas\",
\"rabbit\" => \"carrots\",
\"ogre\" => \"onions\",
);
echo \"\\$myArray has {sizeof($myArray)} elements\\n\";
foreach ($myArray as $key => $value) {
echo \"{$key}: {$value}\\n\";
}
reset($myArray);
next($myArray);
echo \"elem 2:\" . key($myArray) . \": \" . current($myArray) . \"\\n\";
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<?php
ArrayIterator w/ SPL
// file: spl_iterator01.php
$myArray = array (
“monkey” => “bananas”,
“rabbit” => “carrots”,
“ogre” => “onions”,
);
$arrayObj = new ArrayObject($myArray);
$iterator = $arrayObj->getIterator();
echo \"\\$myArray has {$arrayObj->count()} elements\\n\";
while ($iterator->valid()) {
echo \"{$iterator->key()}: {$iterator->current()}\\n\";
$iterator->next();
}
$iterator->seek(1);
echo \"elem 2:{$iterator->key()}: {$iterator->current()}\\n\";
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ArrayIterator Output
$ /usr/bin/php ./nospl_iterator01.php
$myArray has 3 elements
monkey: bananas
rabbit: carrots
ogre: onions
elem 2:rabbit: carrots
Execution time: 0.0020509999999999 microseconds.
$ /usr/bin/php ./spl_iterator01.php
$myArray has 3 elements
monkey: bananas
rabbit: carrots
ogre: onions
elem 2:rabbit: carrots
Execution time: 0.001346 microseconds.
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Interfaces
• Countable
- provides an internal counter
• SeekableIterator
- provides an internal stack seeker
19

<?php
Countable Example
//file: spl_countable01.php
class TequillaCounter implements Countable
{
public function count()
{
static $count = 0;
return ++$count;
}
public function order()
{
$order = $this->count();
echo ($order > 3 ? \"Floor!\" : \"{$order} tequilla\") . PHP_EOL;
}
}
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Countable continued...
$shots = new TequillaCounter();
$shots->order();
$shots->order();
$shots->order();
$shots->order();
Output:
$ /usr/bin/php ./countable01.php
1 tequilla
2 tequilla
3 tequilla
Floor!
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SPL Exceptions
• SPL Exceptions
- templates
- throw exceptions
- common issues
• Types of exceptions
- LogicExceptions
- RuntimeExceptions
22

SPL LogicException Tree
23

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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SPL Functions
• class_implements
Return the interfaces which are implemented by the given class
• class_parents
Return the parent classes of the given class
• iterator_apply
Apply a user function to every element of an iterator
• iterator_count
Count the elements in an iterator
• iterator_to_array
Copy the iterator into an array
• spl_autoload_call
Try all registered __autoload() function to load requested class
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SPL Functions (2)
• spl_autoload_functions
Return all registered __autoload() functions
• spl_autoload_register
Register given function as __autoload() implementation
• spl_autoload_unregister
Unregister given function as __autoload() implementation
• spl_autoload
Default implementation for __autoload()
• spl_classes
Return available SPL classes
• spl_object_hash
Return hash id for given object
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<?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));
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Output of SplFunctions
array(2) {
[\"foo\"]=>
string(3) \"foo\"
[\"bar\"]=>
string(3) \"bar\"
}
array(2) {
[\"bar\"]=>
string(3) \"bar\"
[\"foo\"]=>
string(3) \"foo\"
}
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SplFileInfo
• SplFileInfo::__construct • SplFileInfo::getLinkTarget
• SplFileInfo::getATime • SplFileInfo::getMTime
• SplFileInfo::getBasename • SplFileInfo::getOwner
• SplFileInfo::getCTime • SplFileInfo::getPath
• SplFileInfo::getFileInfo • SplFileInfo::getPathInfo
• SplFileInfo::getFilename • SplFileInfo::getPathname
• SplFileInfo::getGroup • SplFileInfo::getPerms
• SplFileInfo::getInode
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SplFileInfo (2)
• SplFileInfo::getRealPath • SplFileInfo::isReadable
• SplFileInfo::getSize • SplFileInfo::isWritable
• SplFileInfo::getType • SplFileInfo::openFile
• SplFileInfo::isDir • SplFileInfo::setFileClass
• SplFileInfo::isExecutable • SplFileInfo::setInfoClass
• SplFileInfo::isFile • SplFileInfo::__toString
• SplFileInfo::isLink
31

<?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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Data Structures
• Available in PHP 5.3.x
- SplDoublyLinkedList
✓ SplStack
✓ SplQueue
✓ SplHeap
✓ SplMaxHeap
✓ SplMinHeap
✓ SplPriorityQueue
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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
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Not a bridge too far...
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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
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Only one minor thing...
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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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Credits
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/586
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