Load data from and save it to a JSON file on php shutdown exit close.

json-file.php

<?php
namespace LiamKarlMitchell\File;
class JSONFile
{
  public $filename;
  private $data = array();
  
  public function __construct($filename, $defaults = array())
  {
    $this->filename = $filename;
    $this->data     = $defaults;
    $this->load();
    register_shutdown_function(array($this, '__shutdown'));
  }

  public function __shutdown() {
    $this->save();
  }
  
  public function load()
  {
    if (file_exists($this->filename)) {
      $input      = file_get_contents($this->filename);
      $this->data = json_decode($input, true);
    }
  }
  
  public function save()
  {
    file_put_contents($this->filename, json_encode($this->data));
  }
  
  public function __get($key)
  {
    if (isset($this->data[$key])) {
      return $this->data[$key];
    } else {
      return undefined;
    }
  }
  
  public function __set($key, $value)
  {
    $this->data[$key] = $value;
  }
  
  public function __isset($key)
  {
    return isset($this->data[$key]);
  }
}