How you make an OOP Website in PHP

Object-oriented programming (OOP) is a programming paradigm that uses “objects” and their interactions to design applications and computer programs. Programming techniques may include features such as encapsulation, modularity, polymorphism, and inheritance. It was not commonly used in mainstream software application development until the early 1990s. Many modern programming languages now support OOP.

Fundamental Concepts of OOP which takes from Wikipedia:

Class
Defines the abstract characteristics of a thing (object), including the thing’s characteristics (its attributes, fields or properties) and the thing’s behaviors (the things it can do, or methods, operations or features). One might say that a class is a blueprint or factory that describes the nature of something. For example, the class Dog would consist of traits shared by all dogs, such as breed and fur color (characteristics), and the ability to bark and sit (behaviors). Classes provide modularity and structure in an object-oriented computer program. A class should typically be recognizable to a non-programmer familiar with the problem domain, meaning that the characteristics of the class should make sense in context. Also, the code for a class should be relatively self-contained (generally using encapsulation). Collectively, the properties and methods defined by a class are called members.
Object
A pattern (exemplar) of a class. The class of Dog defines all possible dogs by listing the characteristics and behaviors they can have; the object Lassie is one particular dog, with particular versions of the characteristics. A Dog has fur; Lassie has brown-and-white fur.
Instance
One can have an instance of a class or a particular object. The instance is the actual object created at runtime. In programmer jargon, the Lassie object is an instance of the Dog class. The set of values of the attributes of a particular object is called its state. The object consists of state and the behaviour that’s defined in the object’s class.
Method
An object’s abilities. In language, methods are verbs. Lassie, being a Dog, has the ability to bark. So bark() is one of Lassie‘s methods. She may have other methods as well, for example sit() or eat() or walk() or save_timmy(). Within the program, using a method usually affects only one particular object; all Dogs can bark, but you need only one particular dog to do the barking.
Message passing
“The process by which an object sends data to another object or asks the other object to invoke a method.” [2] Also known to some programming languages as interfacing. E.g. the object called Breeder may tell the Lassie object to sit by passing a ‘sit’ message which invokes Lassie’s ‘sit’ method. The syntax varies between languages, for example: [Lassie sit] in Objective-C. In Java code-level message passing corresponds to “method calling”. Some dynamic languages use double-dispatch or multi-dispatch to find and pass messages.
Inheritance
‘Subclasses’ are more specialized versions of a class, which inherit attributes and behaviors from their parent classes, and can introduce their own.
For example, the class Dog might have sub-classes called Collie, Chihuahua, and GoldenRetriever. In this case, Lassie would be an instance of the Collie subclass. Suppose the Dog class defines a method called bark() and a property called furColor. Each of its sub-classes (Collie, Chihuahua, and GoldenRetriever) will inherit these members, meaning that the programmer only needs to write the code for them once.
Each subclass can alter its inherited traits. For example, the Collie class might specify that the default furColor for a collie is brown-and-white. The Chihuahua subclass might specify that the bark() method produces a high pitch by default. Subclasses can also add new members. The Chihuahua subclass could add a method called tremble(). So an individual chihuahua instance would use a high-pitched bark() from the Chihuahua subclass, which in turn inherited the usual bark() from Dog. The chihuahua object would also have the tremble() method, but Lassie would not, because she is a Collie, not a Chihuahua. In fact, inheritance is an ‘is-a’ relationship: Lassie is a Collie. A Collie is a Dog. Thus, Lassie inherits the methods of both Collies and Dogs.
Multiple inheritance is inheritance from more than one ancestor class, neither of these ancestors being an ancestor of the other. For example, independent classes could define Dogs and Cats, and a Chimera object could be created from these two which inherits all the (multiple) behavior of cats and dogs. This is not always supported, as it can be hard both to implement and to use well.
Abstraction
Abstraction is simplifying complex reality by modelling classes appropriate to the problem, and working at the most appropriate level of inheritance for a given aspect of the problem.
For example, Lassie the Dog may be treated as a Dog much of the time, a Collie when necessary to access Collie-specific attributes or behaviors, and as an Animal (perhaps the parent class of Dog) when counting Timmy’s pets.
Abstraction is also achieved through Composition. For example, a class Car would be made up of an Engine, Gearbox, Steering objects, and many more components. To build the Car class, one does not need to know how the different components work internally, but only how to interface with them, i.e., send messages to them, receive messages from them, and perhaps make the different objects composing the class interact with each other.
Encapsulation
Encapsulation conceals the functional details of a class from objects that send messages to it.
For example, the Dog class has a bark() method. The code for the bark() method defines exactly how a bark happens (e.g., by inhale() and then exhale(), at a particular pitch and volume). Timmy, Lassie‘s friend, however, does not need to know exactly how she barks. Encapsulation is achieved by specifying which classes may use the members of an object. The result is that each object exposes to any class a certain interface — those members accessible to that class. The reason for encapsulation is to prevent clients of an interface from depending on those parts of the implementation that are likely to change in future, thereby allowing those changes to be made more easily, that is, without changes to clients. For example, an interface can ensure that puppies can only be added to an object of the class Dog by code in that class. Members are often specified as public, protected or private, determining whether they are available to all classes, sub-classes or only the defining class. Some languages go further: Java uses the default access modifier to restrict access also to classes in the same package, C# and VB.NET reserve some members to classes in the same assembly using keywords internal (C#) or Friend (VB.NET), and Eiffel and C++ allow one to specify which classes may access any member.
Polymorphism
Polymorphism allows the programmer to treat derived class members just like their parent class’ members. More precisely, Polymorphism in object-oriented programming is the ability of objects belonging to different data types to respond to method calls of methods of the same name, each one according to an appropriate type-specific behavior. One method, or an operator such as +, -, or *, can be abstractly applied in many different situations. If a Dog is commanded to speak(), this may elicit a bark(). However, if a Pig is commanded to speak(), this may elicit an oink(). They both inherit speak() from Animal, but their derived class methods override the methods of the parent class; this is Overriding Polymorphism. Overloading Polymorphism is the use of one method signature, or one operator such as ‘+’, to perform several different functions depending on the implementation. The ‘+’ operator, for example, may be used to perform integer addition, float addition, list concatenation, or string concatenation. Any two subclasses of Number, such as Integer and Double, are expected to add together properly in an OOP language. The language must therefore overload the concatenation operator, ‘+’, to work this way. This helps improve code readability. How this is implemented varies from language to language, but most OOP languages support at least some level of overloading polymorphism. Many OOP languages also support Parametric Polymorphism, where code is written without mention of any specific type and thus can be used transparently with any number of new types. Pointers are an example of a simple polymorphic routine that can be used with many different types of objects.[3]
Decoupling
Decoupling allows for the separation of object interactions from classes and inheritance into distinct layers of abstraction. A common use of decoupling is to polymorphically decouple the encapsulation, which is the practice of using reusable code to prevent discrete code modules from interacting with each other.

Not all of the above concepts are to be found in all object-oriented programming languages, and so object-oriented programming that uses classes is called sometimes class-based programming. In particular, prototype-based programming does not typically use classes. As a result, a significantly different yet analogous terminology is used to define the concepts of object and instance, although there are no objects in these languages.

PHP5 also support OOP now. Here we find how we could make a website using OOP technique. The first thing we’re going to look at is make your site object-oriented in a very simple way – we’ll make a site class and a page class. Then we’ll move onto looking at how we could subclass the page class so that we can have different types of page rendering differently.

index.php code:

<?php
include 'config.php';

$site = new csite();

// this is a function specific to this site!
initialise_site($site);

$page = new cpage("Magnolia Shoping cart");
$site->setPage($page);

$content = <<<EOT
Welcome to my Magnolia Shoping Cart!
EOT;
$page->setContent($content);

$site->render();
?>

The config.php file will contain the site-specific information – all the information that shouldn’t be inside our classes and shouldn’t be repeated in every page. We set $site to be an instance of our site, and then call a function called initialise_site() to set it up with our basic, site-specific settings – that function will be in config.php.
Next we create a cpage object, passing into the constructor the title of the page, then use the setPage() function of our csite class to add the page to our site for rendering.
config.php code:
<?php
function __autoload($class) {
include
"$class.php";
}

function

initialise_site(csite $site) {
$site->addHeader("header.php");
$site->addFooter("footer.php");
}
?>

The __autoload() function will load the pages dynamically and in initialise_site() function we add site-specific header and footer files for this site. ote that the __autoload() function will look for csite.php and cpage.php, so we need to supply those two.
csite.php code:
<?php
class csite {
private
$headers;
private
$footers;
private
$page;

public function

__construct() {
$this->headers = array();
$this->footers = array();
}

public function

__destruct() {
// clean up here
}

public function

render() {
foreach(
$this->headers as $header) {
include
$header;
}

$this->page->render();

foreach(

$this->footers as $footer) {
include
$footer;
}
}

public function

addHeader($file) {
$this->headers[] = $file;
}

public function

addFooter($file) {
$this->footers[] = $file;
}

public function

setPage(cpage $page) {
$this->page = $page;
}
}
?>

The cpage.php code:
<?php
class cpage {
private
$title;
private
$content;

public function

__construct($title) {
$this->title = $title;
}

public function

__destruct() {
// clean up here
}

public function

render() {
echo
"<H1>{$this->title}</H1>";

include("body.php");
echo
$this->content;
}

public function

setContent($content) {
$this->content = $content;
}
}
?>

So we’ve got $title and $content variables there.
The header.php file is site-specific, and so could be anything you want. Here’s an example:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML>
<HEAD>
<TITLE>My Website</TITLE>
</HEAD>

<BODY>

<table width="100%" border="0" cellspacing="0" align="center" height="28">
<tr>
<td><img src="images/header.gif" width="100%"></td>
</tr>
</table>
<table width="100%" border="0" cellspacing="0" align="center" height="28">
<tr>
<td align="center"><h2>Magnolia Shoping cart</h2></td>
</tr>
</table>

Here’s a body.php example also:
<table id=”AutoNumber1″ style=”border-collapse: collapse;” border=”0″ cellspacing=”0″ cellpadding=”0″ width=”100%” bordercolor=”#111111″>
<tbody>
<tr>
<td colspan=”3″></td>
</tr>
<tr>
<td width=”23%”><img src=”images/jol3-5.gif” border=”0″ alt=”” width=”86″ height=”100″ /></td>
<td width=”2%” valign=”top”>
<p style=”margin-top: 2px; margin-bottom: 2px;”><strong> </strong></p>
</td>
<td valign=”top”>
<p style=”margin-top: 2px; margin-bottom: 2px;”><strong><span style=”font-family: Verdana; color: #cc3300; font-size: x-small;”>Joy of Learning-I</span></strong></p>

<p style=”text-align: justify; line-height: 12pt; margin-top: 2px; margin-bottom: 2px;”><span style=”letter-spacing: -0.15pt;”><span style=”font-size: x-small;”> <span style=”font-family: Verdana;”>A handbook of 75 activities to help children understand different facets of the environment, developed for the National Council for Educational Research and Training (NCERT). Each activity is presented in a user-friendly format with suggestions as to the subjects in which the activity can be introduced; variations/extensions; ideas for evaluation, etc. Useful for teachers of standards 3 to 5. Pages 88
</span></span></span>
<p class=”MsoNormal” style=”text-align: center; line-height: 12pt; margin-top: 2px; margin-bottom: 2px;”><span style=”font-family: Verdana; font-size: xx-small;”> <a href=”http://www.edutechindia.org/currency.asp?id=1&amp;catid=1&amp;p=m”&gt; Add to Cart </a></span></p>
</td>
</tr>
<tr>
<td colspan=”3″><hr size=”1″ noshade=”noshade” /></td>
</tr>
<tr>
<td width=”23%”><img src=”images/nsins.gif” border=”0″ alt=”” width=”86″ height=”100″ /></td>
<td width=”2%” valign=”top”>
<p style=”margin-top: 2px; margin-bottom: 2px;”><strong> </strong></p>
</td>
<td valign=”top”>
<p style=”margin-top: 2px; margin-bottom: 2px;”><strong><span style=”font-family: Verdana; color: #cc3300; font-size: x-small;”>Nature Scope -Incredible Insects</span></strong></p>

<p style=”text-align: justify; line-height: 12pt; margin-top: 2px; margin-bottom: 2px;”><span style=”letter-spacing: -0.15pt;”><span style=”font-size: x-small;”> <span style=”font-family: Verdana;”>NatureScope India is a creative education series dedicated to inspiring children towards an understanding and appreciation of the natural world while developing the skills they will need to make responsible decisions about the environment. Divided into different sections, each section deals with an insect theme and includes background information and activities related to that theme.In English Pages: 51
</span></span></span>
<p class=”MsoNormal” style=”text-align: center; line-height: 12pt; margin-top: 2px; margin-bottom: 2px;”><span style=”font-family: Verdana; font-size: xx-small;”> <a href=”http://www.edutechindia.org/currency.asp?id=148&amp;catid=1&amp;p=m”&gt; Add to Cart </a></span></p>
</td>
</tr>
<tr>
<td colspan=”3″><hr size=”1″ noshade=”noshade” /></td>
</tr>
<tr>
<td width=”23%”><img src=”images/clothfold.gif” border=”0″ alt=”” width=”86″ height=”100″ /></td>
<td width=”2%” valign=”top”>
<p style=”margin-top: 2px; margin-bottom: 2px;”><strong> </strong></p>
</td>
<td valign=”top”>
<p style=”margin-top: 2px; margin-bottom: 2px;”><strong><span style=”font-family: Verdana; color: #cc3300; font-size: x-small;”>Handmade Seminar Folder with Cloth Covering</span></strong></p>

<p style=”text-align: justify; line-height: 12pt; margin-top: 2px; margin-bottom: 2px;”><span style=”letter-spacing: -0.15pt;”><span style=”font-size: x-small;”> <span style=”font-family: Verdana;”>Available in different colours, designs and patterns. Price Rs. 50.00 onwards.
</span></span></span>
<p class=”MsoNormal” style=”text-align: center; line-height: 12pt; margin-top: 2px; margin-bottom: 2px;”><span style=”font-family: Verdana; font-size: xx-small;”> <a href=”http://www.edutechindia.org/currency.asp?id=158&amp;catid=21&amp;p=m”&gt; Add to Cart </a></span></p>
</td>
</tr>
<tr>
<td colspan=”3″><hr size=”1″ noshade=”noshade” /></td>
</tr>
<tr>
<td width=”23%”><img src=”images/sclabelbirds.gif” border=”0″ alt=”” width=”86″ height=”100″ /></td>
<td width=”2%” valign=”top”>
<p style=”margin-top: 2px; margin-bottom: 2px;”><strong> </strong></p>
</td>
<td valign=”top”>
<p style=”margin-top: 2px; margin-bottom: 2px;”><strong><span style=”font-family: Verdana; color: #cc3300; font-size: x-small;”>School Labels – Birds</span></strong></p>

<p style=”text-align: justify; line-height: 12pt; margin-top: 2px; margin-bottom: 2px;”><span style=”letter-spacing: -0.15pt;”><span style=”font-size: x-small;”> <span style=”font-family: Verdana;”>Sheet of 36 labels
</span></span></span>
<p class=”MsoNormal” style=”text-align: center; line-height: 12pt; margin-top: 2px; margin-bottom: 2px;”><span style=”font-family: Verdana; font-size: xx-small;”> <a href=”http://www.edutechindia.org/currency.asp?id=160&amp;catid=21&amp;p=m”&gt; Add to Cart </a></span></p>
</td>
</tr>
</tbody></table>

Here’s a footer.php example also:
<table width=”100%” border=”0″ cellspacing=”0″ align=”center” height=”28″>
<tr>
<td><img src=”images/footer-toptile.gif”></td>
</tr>
</table>
</BODY>
</HTML>
Now all works complete. Run it to see a very simple site.
Your website is totally developed in OOP way. What a great feelings.
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8 Responses

  1. very informative

    Thanks for sharing with us

    Can you please make one sample application on the basis of above document and place for download as running sample for beginners?

    regards,

  2. After reading this article, I feel that I really need more info. Can you share some more resources ?

  3. Very informative content will subscribe to your RSS Feed.

  4. Excellent tutorial.Thank you.

  5. Thank you very much !

    I think i need some good guidelines and I found !

  6. Can you please make one example code PHP with cookie and session.

    Thanks you !

  7. this is superb……i like so much this page creation…..

    u given a chance to beginners creation a good site pages….

    once again thanks so muchhhhhhhhh

  8. pozycjonowanie
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