Pro PHP- Patterns, Frameworks, Testing and More

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CHAPTER 12

SPL Array Overloading

Array overloading is the process of using an object as an array. Some people coming from

different language backgrounds may know this ability by another name: indexers.

The material in this chapter will help you learn how to create objects that can have their

contents read and manipulated using the standard array syntax.

Introducing ArrayAccess

The ArrayAccess interface enables your objects to behave as arrays. It consists of four methods,

as listed in Table 12-1.

The code in Listing 12-1 shows a very simple form of implementing the ArrayAccess interface,

and it is not even iterable. However, it does demonstrate how the array machinery works.

Listing 12-1. Using ArrayAccess

class MyArray implements ArrayAccess {

protected $_arr;

public function __construct() {

$this->_arr = array();

}

Table 12-1. ArrayAccess Methods

Method Description

offsetSet() Sets an offset for array access. Takes two parameters: an offset to be used as

the array index and a value to assign.

offsetGet() Gets the associated value given a specified offset.

offsetExists() Returns a Boolean value for a given offset to indicate whether (true) or not

(false) a specific key has a value that may be fetched with offsetGet().

offsetUnset() Removes an item from the collection. It is called when you use the unset

statement or set an offset to null.

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