It's time to leap forward and tackle this final article of the series, which will be focused on covering some additional aspects concerning the use of this kind of class method. In addition, I'll teach you how to utilize the "final" keyword, which is included with PHP 5, to prevent the methods of a specific class from being overridden by any subclass.

They work from a hands-on example to show how they can work with private methods (expanding a bit from last time) and how to use the "final" keyword to restrict any and all modification for a method.

Now that you know what will be treated in this fourth chapter of the series, it's time to learn how to declare and implement public and protected methods with PHP 5 classes. Of course, as always I'm going to address this useful topic by using a hands-on approach, which means that there's a bunch of code samples ahead, waiting patiently for you.

They talk about calling methods globally first and then move into the keyword restrictions. They show the difference between a public method/variable and a protected one, including how to get at the protected members from a child class.

In the last article, I explained how to work with a couple of private properties that partially comprised the API of a basic class, which is useful for saving simple strings to a specified text file.

This part builds on this previous example but changes up the subclass (an instance of DataSaver) to use what they call an "accessor" - a function in the parent that returns the private variable/contstant's current value when called.

One of the most useful features that was introduced into the improved object model of PHP 5 is "member visibility." It provides PHP developers with the ability to specify the level of access each data member of a class will have in the context of a given application.

They review the other two keywords (public/protected) before venturing on to the use of "private" to protect, but allow access to, methods and properties in a parent class.

The previous concept can also be applied successfully when it comes to defining the visibility of properties and methods in PHP classes. [...] Using the jargon of object-oriented programming, this capacity is widely known as member visibility. This capacity allows PHP programmers to establish whether the set of methods and properties of a specific class will be public, protected, or private.

They start more generally by looking at how to set up the variables globally and then move down the line talking about restrictions (private/protected/public) and how to get to them in the scripts outside the class.

The following are 5 changes you can make to your wordpress blog that can improve your search engine visibility.

The methods on the list are:

• Permalinks
• Create a sitemap
• Improve the titles of your articles
• Site submissions
• Tagging & Meta Keywords

Details are given on each on implementation.

They start with a look at some of the "accessibility modifiers" that PHP5 has to offer - like private or public - in it's object model. They define them in the context of their database class as well, demonstrating how both variables and classes can be marked this way. After this, it's all about the code, looking first at preparing the SQL query, then validate the SQL before sending it off to the last step - executing the query and fetching the results (if needed).