Using static properties and methods

PHP lets you access properties or methods without having to create an instance of the class. The keyword used for this purpose is static.

How to do it...

1. At its simplest, simply add the static keyword after stating the visibility level when declaring an ordinary property or method. Use the self keyword to reference the property internally:

   class Test
   {
     public static $test = 'TEST';
     public static function getTest()
     {
       return self::$test;
     }
   }

2. The self keyword will bind early, which will cause problems when accessing static information in child classes. If you absolutely need to access information from the child class, use the static keyword in place of self. This process is referred to as Late Static Binding.

3. In the following example, if you echo Child::getEarlyTest(), the output will be TEST. If, on the other hand, you run Child::getLateTest(), the output will be CHILD. The reason is that PHP will bind to the earliest definition when using self,...