This document provides an introduction to the Standard PHP Library (SPL) which includes common interfaces, data structures, and classes. It discusses key SPL interfaces like Countable, ArrayAccess, and Iterator. It also covers common SPL data structures like SPLFixedArray, SPLDoublyLinkedList, SPLStack and SPLQueue. The document demonstrates how to use SPL for filesystem handling with SPLFileInfo and DirectoryIterator. It also discusses the SPLException class and specific exception types.

1. SPL

2. 2
Who am I?
• Lorna Jane Mitchell
• PHP consultant, trainer, and writer
• Personal site at lornajane.net
• Twitter: @lornajane
• PHPNW regular!

3. 3
SPL
• Standard PHP Library
• An extension to do common things
• FAST! Because it's in C
• Lots of functionality (tonight is just a
taster)

4. 4
The SPL Drinking Game
• When anyone says "iterator", take a drink
http://www.flickr.com/photos/petereed/2667835909/

5. 5
Before We Go …
• SPL relies heavily on OOP theory and
interfaces
• Let's recap on some theory

6. 6
OOP

7. 7
Classes vs Objects
• If the class is the recipe …
• Then the object is
the cake
1 <?php
2
3 class CupCake
4 {
5 public function addFrosting($colour, $height)
{
6 // ...
7 }
8 }
9
10 $cupcake = new CupCake();
11 var_dump($cupcake);
http://www.flickr.com/photos/quintanaroo/339856554/

8. 8
Inheritance
• Using classes as "big-picture templates"
and changing details
• Parent has shared code
• Child contains differences
Cake
BirthdayCake CupCake

9. 9
Example: Cake Class
1 <?php
2
3 class Cake
4 {
5 public function getIngredients() {
6 return array("2 eggs", "margarine", "sugar", "flour");
7 }
8 }

10. 10
Example: CupCake Class
1 <?php
2
3 class CupCake
4 {
5 public function addFrosting($colour, $height)
{
6 // ...
7 }
8 }
9
10 $cupcake = new CupCake();
11 var_dump($cupcake);

11. 11
Interfaces
• Define a contract
• Classes implement interfaces - they must
fulfil the contract
• Interfaces define a standard API and
ensure all providers implement it fully

12. 12
Interface Example
1 <?php
2
3
4 interface Audible {
5 function speak();
6 }
7
8 class Sheep implements Audible {
9 function speak() {
10 echo "baaa!";
11 }
12 }
13
14 $animal = new Sheep();
15 if($animal instanceOf Audible) {
16 $animal->speak();
17 } else {
18 echo "*stares blankly*";
19 }
Example taken from http://thinkvitamin.com/code/oop-with-php-finishing-touches/

13. 13
Object Comparison
• Check object types
– type hinting
– instanceOf operator
• Evaluate as true if object either:
– is of that type
– extends that type
– implements that type

14. 14
SPL Interfaces

15. 15
SPL Interfaces
• Countable
• ArrayAccess
• Iterator

16. 16
Countable
• We can dictate what happens when we
count($object)
• Class implements Countable
• Class must now include a method called
count()

17. 17
Countable Example
1 <?php
2
3 class Basket implements Countable
4 {
5 public $items = array();
6
7 public function addItem($item) {
8 $this->items[] = $item;
9 return true;
10 }
11
12 public function count() {
13 return count($this->items);
14 }
15 }
16
http://www.flickr.com/photos/dunbargardens/3740493102/

18. 18
ArrayAccess
• Define object's array behaviour
• Allows us to use array notation with an
object in a special way
• A good example is SimpleXML, allows
array notation to access attributes

19. 19
ArrayAccess
1 <?xml version="1.0" ?>
2 <foodStore>
3 <fridge>
4 <eggs />
5 <milk expiry="2010-11-07" />
6 </fridge>
7 <cupboard>
8 <flour expire="2010-08-31" />
9 </cupboard>
10 </foodStore>
1 <?php
2
3 $xml = simplexml_load_file('foodstore.xml');
4
5 echo $xml->fridge->milk['expiry'];

20. 20
Iterators
• Dictate how we traverse an object when
looping
• Defines 5 methods:
1 <?php
2
3 interface Iterator
4 {
5 public function key();
6 public function current();
7 public function next();
8 public function valid();
9 public function rewind();
10 }

21. 21
More Iterators
• DirectoryIterator
• LimitIterator
• SimpleXMLIterator
• CachingIterator
• ...
• RecursiveIteratorIterator

22. 22
Using SPL

23. 23
Using SPL
• SPL builds on these ideas to give us great
things
• Datastructures
• Filesystem handling
• SPLException

24. 24
Datastructures

25. 25
SPLFixedArray
• An object that behaves like an array
• Fixed length
• Integer keys only
• FAST!!

26. 26
SPLDoublyLinkedList
• Simple and useful computer science
concept
• Ready-to-use implementation
• Can push, pop, iterate …

27. 27
SPLStack, SPLQueue
• Built on the SPLDoublyLinkedList
• No need to home-spin these solutions in
PHP
• Simply extend the SPL ones

28. 28
SPLQueue Example
1 <?php
2
3 class LornaList extends SPLQueue
4 {
5 public function putOnList($item) {
6 $this->enqueue($item);
7 }
8
9 public function getNext() {
10 // FIFO buffer, just gets whatever is oldest
11 $this->dequeue($item);
12 }
13 }
14
15 $todo_list = new LornaList();
16
17 // procastinate! Write the list
18 $todo_list->putOnList("write SPL talk");
19 $todo_list->putOnList("wrestle inbox");
20 $todo_list->putOnList("clean the house");
21
22 // Time to do stuff
23 $task = $todo_list->getNext();
24 echo $task;

29. Filesystem Handling

30. 30
Filesystem Handling
• SPLFileInfo - everything you ever needed
to know about a file
• DirectoryIterator - very neat way of
working with directories and files
• DirectoryIterator returns individual items
of type SPLFileInfo

31. 31
Filesystem Example
• taken directly from devzone
– http://devzone.zend.com/article/2565-The-Standard-PHP-Library-SPL
1 <?php
2
3 $path = new DirectoryIterator('/path/to/dir');
4
5 foreach ($path as $file) {
6 echo $file->getFilename() . "t";
7 echo $file->getSize() . "t";
8 echo $file->getOwner() . "t";
9 echo $file->getMTime() . "n";
10 }

32. 32
Exceptions

33. 33
SPLException
• Many additional exception types
• Allows us to throw (and catch) specific
exceptions
• Including:
– BadMethodCallException
– InvalidArgumentException
– RuntimeException
– OverflowException

34. 34
SPL Exception Example
1 <?php
2
3 class LornaList extends SPLQueue
4 {
5 public function putOnList($item) {
6 if($this->count() > 40) {
7 throw new OverflowException(
8 'Seriously? This is never going to get done'
9 );
10 } else {
11 $this->enqueue($item);
12 }
13 }
14
15 public function getNext() {
16 // FIFO buffer, just gets whatever is oldest
17 $this->dequeue($item);
18 }
19 }
20

35. 35
SPL

36. 36
SPL
• Interfaces
• Datastructures
• File handling
• Exceptions
• … and so much more

37. 37
Questions?

38. 38
Resources
• PHP Manual
http://uk2.php.net/manual/en/book.spl.php
• DevZone Tutorial
http://devzone.zend.com/article/2565-The-Standard-PHP-Library-SPL
• PHPPro Article
http://www.phpro.org/tutorials/Introduction-to-SPL.html