Detailed code explanation of the ArrayAccess interface in php

The dependency injection in slim is based on pimple, so I went to learn pimple again. Compared with the dependency injection class I wrote before, pimple has a very new usage. Instead of using

$container->session_storage = function ($c) {
    return new $c['session_storage_class']($c['cookie_name']);
};

, it is injected in an array:

$container['session_storage'] = function ($c) {
    return new $c['session_storage_class']($c['cookie_name']);
};

When I looked at the source code, I realized that the trick is On the ArrayAccess interface provided by php5.
Official definition: An interface that provides the ability to access objects like accessing arrays.
This interface mainly defines four abstract methods:

abstract public boolean offsetExists ( mixed $offset ) #检查数据是否存在
abstract public mixed offsetGet ( mixed $offset )      #获取数据
abstract public void offsetSet ( mixed $offset , mixed $value )     #设置数据   
abstract public void offsetUnset ( mixed $offset ) #删除数据

If you want the object to be used like a PHP array, then we need to implement ArrayAccess Interface

The code is as follows:

interface ArrayAccess 
boolean offsetExists($index) 
mixed offsetGet($index) 
void offsetSet($index, $newvalue) 
void offsetUnset($index)

The following example shows how to use this interface. The example is not complete, but it is enough to understand, :->

The code is as follows:

<?php 
class UserToSocialSecurity implements ArrayAccess 
{ 
private $db;//一个包含着数据库访问方法的对象 
function offsetExists($name) 
{ 
return
 $this->db->userExists($name); 
} 
function offsetGet($name) 
{ 
return $this->db->getUserId($name); 
} 
function offsetSet($name, $id) 
{ 
$this->db->setUserId($name, $id); 
} 
function offsetUnset($name) 
{ 
$this->db->removeUser($name); 
} 
} 
$userMap = new UserToSocialSecurity(); 
print "John&#39;s ID number is " . $userMap[&#39;John&#39;]; 
?>

In fact, when the $userMap['John'] search is executed, PHP calls the offsetGet() method, which is then called Database-related getUserId() method.

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