So, let's get to it.


PHP's Object-Oriented Programming support is kind of iffy, given it was introduced back in PHP 5.0 (IIRC), but nevertheless it's there and can be quite useful. What differs classes from functions is that classes allow a degree of organization and structure to your web application. Most of all, they make easier one the core principles in programming, especially OOP; DRY - Don't Repeat Yourself. It really shines when you need to use an object multiple times. Let's check it out.

---

<?php

class firstClass{
//Class content
}

// Instantiate the class by calling the class name; here "firstClass"
$ob = new firstClass;
?>

---

As you can see, the setup for and calling of a class differs from that of a function, but it probably doesn't look too exciting or useful yet.
Let's start populating the class:

---

<?php

class firstClass{

public $obj = "I have value!";

public function hullBreach($shiny){
echo "<br />I like shiny things, like " . $shiny . "!";
}

}

$ob = new firstClass;

echo $ob->obj;
$ob->hullBreach("gold";
?>

Results:

I have value!
I like shiny things, like gold!

---

There's a bit to cover here. First new thing you probably noticed was "public". Classes allow you to set the "visibility" (accessibility within the application) of your objects. "public" objects can be accessed anywhere within or outside the class. The others are "protected" (can be accessed only in the current class and any descendant class; more on that later) and "private" (can ONLY be accessed in the class it's in). Next, you probably noticed the arrow in the $ob variable. The "->" operator is used to access variables and functions within a class, akin to the "." operator in JavaScript. Here it is used simply to print out some stuff (SHINY!)

If there's some code you'd like run when the class is accessed or ends - very useful for PDO/MySQLi Database connection classes - you can make use of the built-in __construct() and __destruct() functions (note that there are 2 underscores in front of those functions):

---

<?php

class firstClass{

protected function hullBreach($shiny){
echo <<<EOD
My name is Daniel Gump, resident breacher of hulls.
I like shiny things, like {$shiny}!
I also codez things like TMJ. It'll be out [ strike ]2011[ /strike ] [ strike ]2012[ /strike ] ...Coming Soon!
EOD;
}


function __construct(){
echo "Class" . __CLASS__ . "has been accessed.<br />";
//__CLASS__ is a constant that contains the name of the class it's in
}

protected function __destruct(){
echo "<br />Class " . __CLASS__ . "was closed";
}

}

$ob = new firstClass;
$ob->hullBreach("schist"
?>

Results:

Class firstClass was accessed

My name is Daniel Gump, resident breacher of hulls.
I like shiny things, like schist!
I also codez things like TMJ. It'll be out 2011 2012 ...Coming Soon!

Class firstClass was terminated

---

Well, that's it for this (VERY) brief intro to OOP and classes in PHP.
Hope it helped some of you.

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"I want to live my life always taking the risk that I don't know anything like enough yet, that I can't know enough; that I'm always - hungrily - operating on the margins of a potentially great harvest of future knowledge and wisdom. Which means that to me, the offer of certainty, the offer of complete security, the offer of an impermeable faith that can't give way, is the offer of something not worth having.
[...]
Take the risk of thinking for yourself. Much more happiness, truth, beauty and wisdom, will come to you that way."
-Christopher Hitchens (1949 - 2011)