SPL

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Who am I?

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

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SPL

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

taster)

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The SPL Drinking Game

• When anyone says "iterator", take a drink

http://www.flickr.com/photos/petereed/2667835909/

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Before We Go …

• SPL relies heavily on OOP theory and interfaces

• Let's recap on some theory

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OOP

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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/

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Inheritance

• Using classes as "big-picture templates" and changing details

• Parent has shared code• Child contains differences

Cake

BirthdayCake CupCake

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Example: Cake Class

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

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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);

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Interfaces

• Define a contract• Classes implement interfaces - they must

fulfil the contract• Interfaces define a standard API and

ensure all providers implement it fully

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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/

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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

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SPL Interfaces

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SPL Interfaces

• Countable• ArrayAccess• Iterator

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Countable

• We can dictate what happens when we count($object)

• Class implements Countable• Class must now include a method called

count()

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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/

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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

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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'];

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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 }

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More Iterators

• DirectoryIterator• LimitIterator• SimpleXMLIterator• CachingIterator• ...• RecursiveIteratorIterator

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Using SPL

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Using SPL

• SPL builds on these ideas to give us great things

• Datastructures• Filesystem handling• SPLException

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Datastructures

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SPLFixedArray

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

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SPLDoublyLinkedList

• Simple and useful computer science concept

• Ready-to-use implementation• Can push, pop, iterate …

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SPLStack, SPLQueue

• Built on the SPLDoublyLinkedList• No need to home-spin these solutions in

PHP• Simply extend the SPL ones

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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;

Filesystem Handling

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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

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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 }

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Exceptions

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SPLException

• Many additional exception types• Allows us to throw (and catch) specific

exceptions• Including:

– BadMethodCallException– InvalidArgumentException– RuntimeException– OverflowException

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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

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SPL

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SPL

• Interfaces• Datastructures• File handling• Exceptions• … and so much more

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Questions?

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Resources

• PHP Manualhttp://uk2.php.net/manual/en/book.spl.php

• DevZone Tutorialhttp://devzone.zend.com/article/2565-The-Standard-PHP-Library-SPL

• PHPPro Articlehttp://www.phpro.org/tutorials/Introduction-to-SPL.html