This is a typical PHP 4 code - if you wanted to duplicate an object, you had to copy it and assign a new value to it. In PHP 5 the coder can simply use the "clone". Here is how the same code will look in PHP 5 :.
Since we were chaning only the name, we "cloned" the first object and simply changed the value that needed changing. With PHP 5 you can safely create class constants that act in very much the same way as do defined constants, but are limited within a class definition and can be accessed with "::".
Have in mind that constants must have a constant expression for a value; they can't be equal to a variable or a result of a function call. Here is how you can define a constant: PHP Code:. When a class member is declared as static, it's accessible with "::" without an instance. In PHP 5 another addition is the "visibility" of the class methods and properties.
The visibility has 3 levels:. In PHP 4 the constructor was just a method with the same name as the name of the class. So, if you changed the name of the class, you had to go and update it every time it was used. When used, the code will be executed only when the object is destroyed. With PHP 5 you can also create the so called "abstract" classes. These are classes, which are used only as a model to define other classes.
If a certain class contains abstract method, it must be defined as abstract. The interface will define the methods, which must be implemented in a class. Have in mind that all methods which are defined in an interface must be public. A big advantage of this new addition is that in a class you can implement any number of interfaces. Here is how it all works :. You can only extend an abstract class Also, a class must be defined as abstract if it contains any abstract methods.
And those abstract methods must be defined within the class which extend that abstract class. You can include complete method definitions within the abstract methods of abstract class. This error levels notifies you when you use depreciated PHP code. This function allows you to avoid writing a long list of includes at the top of your script by defining them inside this function. Methods are accessible to everyone including objects outside the classes. And properties readable and writable by everyone including objects outside the classes.
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