Naturally, a good place to start demonstrating the creation and usage of bridge objects with PHP 5 is with developing a practical example where these types of objects are utilized to perform a given task.

In this case, the example that I’m going to set up will be based upon creating first a target object, called “Message,” which will be tasked with displaying some trivial strings to the browser. Next, I’m going to define a bridge class that will be capable of saving the mentioned target object to different storage locations, like a plain text file, an array structure and a simple cookie.

Hopefully, after you see how this bridge class looks, you’ll realize how its instantiation can be separated from its corresponding implementation, since both things will reside on different class hierarchies.

So far, so good. The process for building a bridge class seems really straightforward, therefore let me show you the first target class involved in this creation process. As I said before , it is named “Message,” and its simple signature is shown below:

// define 'Message' class (target object for 'BridgeObjectSaver' class)

class Message{

	private $message;

	public function __construct($message='Default Message'){

		if(!$message||!is_string($message)||strlen

($message)>255){

			throw new Exception('Invalid input message');

		}

		$this->message=$message;

	}

	public function getMessage(){

		return $this->message;

	}
}

As illustrated above, the “Message” sample class is really simple to understand. All this class does is accept an input string as the unique parameter, which will be returned to calling code with the trivial purpose of being displayed on the browser, or receiving similar processing. Extremely easy, right?

Well, I have to admit that the previous target class is rather primitive, but for my purpose of showing you how a bridge class can be created with PHP 5, the definition for this class is more than enough, at least for now.

Therefore, having shown the signature of the respective “Message” class, it’s a good time to leap forward and learn how to build a bridge class. This class will use “Message” objects and save them to different storage locations, including text files, arrays and cookies respectively.

Do you want to see how this brand new bridge class will be created? All right, jump into the following section and keep reading.