When we write programs, we may often get into a situation where we don't know whether we should use Abstract class or Interface when we want to define an abstract object. These two are very similar and they are interchangeable. On Stackoverflow, this question is asked many times, it's related to many programming languages. Also in the official documentation of PHP regarding the Abstract class and Interface, people are arguing about this. To understand this question, we need to understand their differences and use scenarios.

They provide examples of abstract class and interface usage with one of the main differences being that you can define functionality in abstract classes. There's also examples showing classes that extend the abstract class while implementing the interface at the same time, helping to define the object structure to an even finer level.

There are many benefits of inheritance with PHP, the most common is simplifying and reducing instances of redundant code. Class inheritance may sound complicated, but think of it this way. Consider a tree. A tree is made up of many parts, such as the roots that reside in the ground, the trunk, bark, branches, leaves, etc. Essentially inheritance is a connection between a child and its parent. [...] This article assumes a basic understanding of OOP with PHP.

They show how to create the parent object as a base and how to inherit it into a child class - using the extend keyword in the class definition. They give an example of their sample code in action so you can see how the inheritance is handled.

After a brief few weeks studying Perl and its nuances I'm going to take a look at PHP5 Objects.

One of the annoying things with object in PHP 4 was you had to use a lot of references, you know, that funny & symbol. No longer needed in PHP 5 because you use "Object Handles" perhaps similar to a file handler you when fopen a file. Also available now are access modifiers "public/protected/package" and interface implementation. I can hear the beer mugs of java programmers being raised in celebration to this one. Also new to PHP 5 are real constructors and destroy methods. There are many more features, but lets see some code.

There are code examples that show some of the new keywords (private, public, etc) that the object structure uses, as well as how you can use them. They link to the PDF of Power PHP 5 Programming for a good place to start...]]> Wed, 18 Jan 2006 06:40:42 -0600