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04.classes.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Webscripting1 — Serverside Webscripting — 04.classes</title>
<meta name="description" content="Webscripting1 — Serverside Webscripting — 04.classes">
<meta name="author" content="Bram(us) Van Damme - ikdoeict.be">
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<div id="reveal">
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<div class="slides">
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<section>
<section>
<h3 class="inverted">Serverside Webscripting <small>[JLW322]</small></h3>
<h1>04.classes</h1>
<footer>
<em><a href="http://www.ikdoeict.be/">ikdoeict.be</a> — <a href="mailto:[email protected]">[email protected]</a></em>
</footer>
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<section>
<section>
<h2>Examples</h2>
<footer>Watch and learn ...</footer>
</section>
<section>
<h2>Basic Class</h2>
<pre class="bigger"><code class="language-php" data-overlay-example="assets/04/examples/01.php"><?php
class BasicClass {
private $var1;
protected $var2;
public $var3;
public function __construct($var) {
$this->var1 = $var;
$this->var2 = $var;
$this->var3 = $var;
}
public function doubleVar3() {
$this->var3 = $this->var3 . ' ' . $this->var3;
}
public function getVar1() {
return $this->var1;
}
}
$inst = new BasicClass('foo');
echo $inst->getVar1() . PHP_EOL;
$inst->doubleVar3();
echo $inst->var3;</code></pre>
</section>
<section>
<h2>Constants</h2>
<pre class="bigger"><code class="language-php" data-overlay-example="assets/04/examples/02.php"><?php
class BasicClass {
const CLASS_CONSTANT = 12.7;
public function multiply($x) {
return $x * self::CLASS_CONSTANT;
}
}
echo BasicClass::CLASS_CONSTANT . PHP_EOL;
$inst = new BasicClass();
echo $inst->multiply(3) . PHP_EOL;</code></pre>
</section>
<section>
<h2>Static Variables & Static Methods</h2>
<pre class="bigger"><code class="language-php" data-overlay-example="assets/04/examples/03.php"><?php
class BasicClass {
static $staticVariable;
public function __construct($name) {
self::$staticVariable = $name;
}
public static function staticFunction($ohai) {
echo $ohai . PHP_EOL;
}
}
BasicClass::staticFunction('O Hi');
$inst = new BasicClass('foo');
$inst2 = new BasicClass('bar');
echo $inst::$staticVariable . PHP_EOL;
echo $inst2::$staticVariable . PHP_EOL;</code></pre>
</section>
<section>
<h2>Inheritance (1)</h2>
<pre class="bigger"><code class="language-php" data-overlay-example="assets/04/examples/04.php"><?php
class Animal {
private $name;
public function __construct($name) {
$this->name = $name;
}
protected function say($what) {
return $what;
}
}
class Dog extends Animal {
public function bark() {
echo $this->say('WOOF!');
}
}
$dog = new Dog('Sparky');
$dog->bark();</code></pre>
</section>
<section>
<h2>Inheritance (2)</h2>
<pre class="bigger"><code class="language-php" data-overlay-example="assets/04/examples/05.php"><?php
class Animal {
private $name;
public function __construct($name) {
$this->name = $name;
}
final function getName() { // cannot be overridden!
echo $this->name;
}
}
class Dog extends Animal {
public function __construct($name) {
echo 'Yo dawg!' . PHP_EOL;
parent::__construct($name); // call parent function
}
}
$dog = new Dog('Sparky');
echo $dog->getName() . PHP_EOL;</code></pre>
</section>
<section>
<h2>Inheritance (3)</h2>
<pre class="bigger"><code class="language-php" data-overlay-example="assets/04/examples/06.php"><?php
abstract class Animal {
private $name;
public function __construct($name) {
$this->name = $name;
}
abstract public function doTrick();
}
class Dog extends Animal {
private $tricks = array('jump', 'lay down', 'roll over', 'play dead');
public function doTrick() {
return $this->tricks[rand(0, sizeof($this->tricks) - 1)];
}
}
$dog = new Dog('Sparky');
echo $dog->doTrick();</code></pre>
</section>
</section>
<section>
<section>
<h2>Summary</h2>
<footer>The examples in words</footer>
</section>
<section>
<h2>Classes Summary (1)</h2>
<ul>
<li class="fragment">
Class basics
<ul class="fragment">
<li>Define a class with the <code>class</code> keyword</li>
<li>Create an instance with the <code>new</code> keyword</li>
</ul>
</li>
<li class="fragment">
Variables / methods
<ul class="fragment">
<li>Define a method with the <code>function</code> keyword</li>
<li>Defining a variable requires no specific keyword</li>
<li>Scope is <code>public</code>, <code>protected</code>, or <code>private</code></li>
<li>Accessible/Callable via <code>$this->dataMember</code> <em>(internal)</em> or <br /><code>$instance->dataMember</code> <em>(external, if scope allows it)</em></li>
</ul>
</li>
<li class="fragment">
Constructor and destructor are <em>Magic Methods</em>
<ul class="fragment">
<li><code>__construct()</code> and <code>__destruct()</code></li>
</ul>
</li>
</ul>
</section>
<section>
<h2>Classes Summary (2)</h2>
<ul>
<li class="fragment">
Class constants
<ul class="fragment">
<li>Use the <code>const</code> keyword and immediately assign a value</li>
<li>No <code>$</code> for name and ALLCAPS</li>
<li>Accessible via <code>self::SOME_CONSTANT</code> (internal) or <code>ClassName::SOME_CONSTANT</code> (external)</li>
<li>Value cannot be changed at runtime</li>
</ul>
</li>
<li class="fragment">
Static variables and methods
<ul class="fragment">
<li>Use the (extra) <code>static</code> keyword</li>
<li>Static variables' value shared amongst instances</li>
<li>Static methods callable without an instance</li>
<li>Accessible/Callable via <code>ClassName::$someStaticVariable</code> / <code>ClassName::someStaticMethod()</code></li>
</ul>
</li>
</ul>
</section>
<section>
<h2>Classes Summary (3)</h2>
<ul>
<li class="fragment">
Inheritance
<ul class="fragment">
<li>Defined with the <code>extends</code> keyword</li>
<li>Overriding methods must have the same, or a less restrictive scope</li>
<li>Call parent class methods with <code>parent::nameOfTheMethod()</code> <em>(even if it's a non-static method!)</em></li>
</ul>
</li>
<li class="fragment">
Final classes and methods
<ul class="fragment">
<li>Cannot be extended / overridden</li>
<li>Defined with the (extra) <code>final</code> keyword</li>
</ul>
</li>
<li class="fragment">
Abstract classes and methods
<ul class="fragment">
<li>Defined with the (extra) <code>abstract</code> keyword</li>
<li>Cannot be instantiated / called; Must be implemented in the derivative class / methods</li>
<li>If a class contains an abstract method, the class itself must be abstract too</li>
</ul>
</li>
</ul>
</section>
</section>
<section>
<section>
<h2>Want more?</h2>
</section>
<section>
<h2>Not talked about</h2>
<ul>
<li class="fragment">
Interfaces
<ul class="fragment">
<li>Define an interface with the <code>interface</code> keyword</li>
<li>A class can implement an interface via the <code>implements</code> keyword</li>
<li>A class can implement multiple interfaces</li>
<li>An interface itself cannot be instantiated</li>
</ul>
</li>
<li class="fragment">
Multiple Inheritance
<ul class="fragment">
<li>Not supported by PHP</li>
<li>Use <a href="http://php.net/manual/en/language.oop5.traits.php">traits</a> to reduce some limitations of single inheritance</li>
</ul>
</li>
<li class="fragment">
<a href="http://php.net/manual/en/language.namespaces.php">Namespaces</a>
<ul class="fragment">
<li>Available since PHP 5.3.0</li>
<li>Provides a way to group related classes, interfaces, functions and constants</li>
</ul>
</li>
</ul>
</section>
</section>
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<h2>Questions?</h2>
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<em><a href="http://www.ikdoeict.be/">ikdoeict.be</a> — <a href="mailto:[email protected]">[email protected]</a></em>
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<h2>Sources</h2>
<ul>
<li><a href="http://php.net/manual/en/language.oop5.static.php">http://php.net/manual/en/language.oop5.static.php</a></li>
</ul>
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