A quick overview of some but by no means all of the features of the SPL extension

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