imd465 Senior Project

What is Object Oriented programing (OOP) in PHP?

I want to create my new project by using Object Orientated Programing, so I have done some research into using OOP in PHP. So, from the articles I have read and the videos I have watched, this is my explanation of OOP.

Object Orientated Programing (OOP) is a way to group code together by a common theme for reusablity. You create objects that have attributes and actions similar to a physical object. Creating code in this way makes it easier to read the code and it also makes the code more modular.

For example a chair has legs, a seat, a back, and a color and it can hold a person. The chair is the object, its characteristics are the attributes, and it’s actions are methods.

• Classes - the object itself
• Attributes - variable specific to the object
• Methods - functions specific to the object

class Chair {
   var $legs;
   var $back;
   var $color;

   function SitOn( ) {
     echo "A person is sitting on this chair.";
   }

   function GetUp( ) {
     echo "A person got out of the chair";
   }

}

Creating a class does not add a chair to the project. It is like a blueprint for a class. The class shows what a chair would look like if there were a chair. To have a chair we need to create a chair from the blueprint. This is called Instantiation or creating an instance.

$chair = new Chair;

After the chair is created we can set the attributes and call the methods.

$Chair->color = "blue";
$Chair->legs = "4";
$Chair->SitOn();

These properties can also be set by default within the class. Then each new chair will automatically have these properties.

class Chair {
   var $legs  = "4";
   var $back;
   var $color = "4";

   function SitOn( ) {
     echo "A person is sitting on this chair.";
   }

   function GetUp( ) {
     echo "A person got out of the chair";
   }

}

Each new chair will have four legs and will be blue.

The variables and methods of a class can be limited with access modifiers.

• Public - any part of the application has access
• Protected - only this class sub classes of this class have access
• Private - only this class has access

class Chair {
   Public $legs  = "4";
   Private $back;
   Public $color = "4";

   Public function SitOn( ) {
     echo "A person is sitting on this chair.";
   }

   Protected function GetUp( ) {
     echo "A person got out of the chair";
   }

}

There is one more access modifier called static. The static modifiers belong to the class and not to the instance. For example you may want to have a variable that holds the current number of chairs.

class Chair {
   Public $legs          = "4";
   Private $back;
   Public $color         = "4";
   Static $totalChairs   = "7"

   Public function SitOn( ) {
     echo "A person is sitting on this chair.";
   }

   Protected function GetUp( ) {
     echo "A person got out of the chair";
   }

}

These are accessed within your code by using the class name a double colon.

echo Chair::$totalChairs;

We can also set up methods that will run instantly on Instantiation or on the destruction of the instance. These are called constructors and destructors.

class Chair {
   Public $legs          = "4";
   Private $back;
   Public $color         = "4";
   Static $totalChairs   = "7"

   function __construct() {
     echo "Your have created a new chair";
     self::$counter++;
   }

   Public function SitOn( ) {
     echo "A person is sitting on this chair.";
   }

   Protected function GetUp( ) {
     echo "A person got out of the chair";
   }

   function __destruct() {
     echo "Your have destroyed the chair";
     self::$counter--;
   }

}

These are some of the basic principles of OOP in PHP. There is more to it and I hope to learn more as I start to implement it in my project.