Versions

[{“Name”:“4.0”,“GroupName”:“PHP 4.x”},{“Name”:“4.1”,“GroupName”:“PHP 4.x”},{“Name”:“4.2”,“GroupName”:“PHP 4.x”},{“Name”:“4.3”,“GroupName”:“PHP 4.x”},{“Name”:“5.0”,“GroupName”:“PHP 5.x”},{“Name”:“4.4”,“GroupName”:“PHP 4.x”},{“Name”:“5.1”,“GroupName”:“PHP 5.x”},{“Name”:“5.2”,“GroupName”:“PHP 5.x”},{“Name”:“5.3”,“GroupName”:“PHP 5.x”},{“Name”:“5.4”,“GroupName”:“PHP 5.x”},{“Name”:“5.5”,“GroupName”:“PHP 5.x”},{“Name”:“5.6”,“GroupName”:“PHP 5.x”},{“Name”:“7.0”,“GroupName”:“PHP 7.x”},{“Name”:“7.1”,“GroupName”:“PHP 7.x”}]

Introduction

Classes and Objects are used to to make your code more efficient and less repetitive by grouping similar tasks.

A class is used to define the actions and data structure used to build objects. The objects are then built using this predefined structure.

Syntax

• class <ClassName> [ extends <ParentClassName> ] [ implements <Interface1> [, <Interface2>, ... ] { } // Class declaration
• interface <InterfaceName> [ extends <ParentInterface1> [, <ParentInterface2>, ...] ] { } // Interface declaration
• use <Trait1> [, <Trait2>, ...]; // Use traits
• [ public | protected | private ] [ static ] $<varName>; // Attribute declaration
• const <CONST_NAME>; // Constant declaration
• [ public | protected | private ] [ static ] function <methodName>([args...]) { } // Method declaration

Remarks

Classes and Interface components

Classes may have properties, constants and methods.

• Properties hold variables in the scope of the object. They may be initialized on declaration, but only if they contain a primitive value.
• Constants must be initialized on declaration and can only contain a primitive value. Constant values are fixed at compile time and may not be assigned at run time.
• Methods must have a body, even an empty one, unless the method is declared abstract.

class Foo {
    private $foo = 'foo'; // OK
    private $baz = array(); // OK
    private $bar = new Bar(); // Error!
}

Interfaces cannot have properties, but may have constants and methods.

• Interface constants must be initialized on declaration and can only contain a primitive value. Constant values are fixed at compile time and may not be assigned at run time.
• Interface methods have no body.

interface FooBar {
    const FOO_VALUE = 'bla';
    public function doAnything();
}