basic_datacontainer_1.php

## basic_datacontainer_1.php
<?php
class DataContainer
{
  public static $data = array();

	public function __set( $name, $value ) {
		self::$data[$name] = $value;
	}

	public function __get( $name ) {
		if ( isset( self::$data[$name] ) )
			return self::$data[$name];
		else
			return null;
	}
}

class Bar extends DataContainer
{
	public function hello_foo() {
		printf( 'Foo used inside %s: %s<br>', __CLASS__, $this->foo );
	}
}

function set_foo( $var ) {
	$dc = new DataContainer;
	$dc->foo = $var;
}

function print_something() {
	$dc = new DataContainer;
	$foo = $dc->foo;
	print( "Foo inside DataContainer: {$dc->foo}<br> Foo as local variable: {$foo}<br>" );
}

function do_something() {
	$dc = new DataContainer;
	$foo = &$dc::$data['foo'];
	$foo = (int) $foo;
	$foo++;
}

set_foo( '1' );
print_something();
do_something();

$dc = new DataContainer();
echo "Foo is now: {$dc->foo}<br>";

$bar = new Bar();
$bar->hello_foo();

## basic_datacontainer_2.php
<?php
class DataContainer
{
	public static $data = array();

	public function __set( $name, $value ) {
		self::$data[$name] = $value;
	}

	public function __get( $name ) {
		if ( isset( self::$data[$name] ) )
			return self::$data[$name];
		else
			return null;
	}
}

function set_foo( $var ) {
	$dc = new DataContainer;
	$dc->foo = $var;
}

function print_something() {
	$dc = new DataContainer;
	$foo = $dc->foo;
	print( "Foo im DataContainer: {$dc->foo}<br> Foo als lokale Variable: {$foo}<br>" );
}

function do_something() {
	$dc = new DataContainer;
	$foo = &$dc::$data['foo'];
	$foo = (int) $foo;
	$foo++;
}

set_foo( '1' );
do_something();

$dc = new DataContainer();
echo "Foo is now: {$dc->foo}";

## complete_example.php
<?php
/*
 * mocking set_transient() and get_transient()
 */
function set_transient( $key, $data, $lifetime ) {
	// ignore lifetime
	( ! session_id() ) AND session_start();
	$_SESSION[$key] = $data;
	session_write_close();

	return true;
}

function get_transient( $key ) {
	( ! session_id() ) AND session_start();
	return ( isset( $_SESSION[$key] ) ) ? $_SESSION[$key] : false;
}

class DataContainer
{
	public static $data = array();

	private static $protected = array();

	private static $is_saved = false;

	public function __construct() {
		if ( empty( self::$data ) && false != ( $transient = get_transient( self::TRANSIENT_KEY ) ) )
			self::$data = $transient;

		// save the data in a transient when the script end
		register_shutdown_function( array( __CLASS__, 'shutdown' ) );
	}

	public function __destruct() {
		self::shutdown();
	}

	public function __set( $name, $value ) {
		if ( ! in_array( $name, self::$protected ) )
			self::$data[$name] = $value;
	}

	public function __get( $name ) {
		if ( isset( self::$data[$name] ) )
			return self::$data[$name];
		else
			return null;
	}

	public static function shutdown() {
		// save the data only once (__destruct or shutdown)
		if ( true === self::$is_saved )
			return false;

		// save the transient for one day
		set_transient( self::TRANSIENT_KEY, self::$data, DAY_IN_SECONDS );

		self::$is_saved = true;
		return true;
	}

	public static function protect( $name ) {
		self::$protected[$name] = true;
	}

	public static function unprotect( $name ) {
		if ( isset( self::$protected[$name] ) )
			self::$protected[$name] = false;
	}
}

$abba = new DataContainer();
$abba->waterloo = 'DaDaaaDa';
$abba->tonight  = 'Uhuuuu';
$abba::protect( 'tonight' );
echo '<pre>';
print_r($abba::$data);
echo '</pre><hr>';

function elvis() {
	$elvis = new DataContainer();
	echo "Elvis sagt Waterloo sei <em>{$elvis->waterloo}</em> <br>";

	$yeah = 'Yeah! Yeah! Yeah!';
	echo "Elvis setzt Tonight auf <em>{$yeah}</em><br>";
	$elvis->tonight = $yeah;

	echo "Tonight ist jetzt: <em>{$elvis->tonight}</em><br>";
}

elvis();
echo '<hr>';

class Status_Quo
{
	private $sdc = null;

	public function __construct() {
		$this->sdc = new DataContainer();
	}

	public function waterloo() {
		echo "Status Quou singt Waterloo: <em>{$this->sdc->waterloo}</em><br>";
	}

	public function tonight( $new_value = "one-two-three" ) {
		echo "Status Quo setzt Tonight auf <em>{$new_value}</em><br>";
		$this->sdc->tonight = $new_value;
		echo "Tonight ist jetzt <em>{$this->sdc->tonight}</em><br>";
	}
}

$sq = new Status_Quo();
$sq->waterloo();
$sq->tonight();
echo '<hr>';

class Abba extends DataContainer
{
	private $sdc = null;

	public function __construct() {
		$this->sdc = (object) self::$data;
	}

	public function waterloo() {
		$waterloo = self::$data['waterloo'];
		echo "Waterloo, {$waterloo}<br>";
	}

	public function tonight() {
		echo "Tonight, {$this->sdc->tonight}<br>";
	}
}

$abba = new Abba();
$abba->waterloo();
$abba->tonight();

## readonly_datacontainer.php
<?php
class DataContainer
{
  public static $data = array();

  public static $protected = array();

  public function __set( $name, $value ) {
    if ( ! in_array( $name, self::$protected ) )
      self::$data[$name] = $value;
  }

  public function __get( $name ) {
    if ( isset( self::$data[$name] ) )
      return self::$data[$name];
    else
      return null;
  }

  public static function protect( $name ) {
    if ( ! in_array( $name, self::$protected ) )
      array_push( self::$protected, $name );
  }
}

function good_foo() {
  $dc = new DataContainer();
  $dc->foo = 'protected foo';
  $dc->bar = 'unprotected bar';
  $dc->protect( 'foo' );
}

function bad_bar() {
  $dc = new DataContainer();
  $dc->foo = 'hahaha!';
  $dc->bar = 'I change everything!';
}

$dc = new DataContainer();

echo "Set <code>foo</code> to <b>protected foo</b> and <code>bar</code> to <b>unprotected bar</b><br>";
good_foo();

echo "Try to overwrite <code>foo</code> and <code>bar</code><br>";
bad_bar();

echo "<code>foo</code> is still <b>{$dc->foo}</b> and <code>bar</code> is now <b>{$dc->bar}</b><br>";

## save_in_session.php
<?php
class DataContainer
{
	const SESSION_KEY = 'Example_DataConatiner';

	public static $data = array();

	public function __construct() {
		( ! session_id() ) AND session_start();

		if ( isset( $_SESSION[self::SESSION_KEY] ) && ! empty( $_SESSION[self::SESSION_KEY] ) )
			self::$data = $_SESSION[self::SESSION_KEY];

		register_shutdown_function( array( $this, '__destruct' ) );
	}

	public function __destruct() {
		( ! session_id() ) AND session_start();

		$_SESSION[self::SESSION_KEY] = self::$data;
		session_write_close();
	}

	public function __set( $name, $value ) {
		self::$data[$name] = $value;
	}

	public function __get( $name ) {
		if ( isset( self::$data[$name] ) )
			return self::$data[$name];
		else
			return null;
	}

	public static function reset() {
		self::$data = array();
		unset($_SESSION[self::SESSION_KEY]);
		session_write_close();
	}
}

$dc  = new DataContainer();
$uri = $_SERVER['PHP_SELF'];

if ( null === $dc->session_data ) {
	$dc->session_data = 'Value from previous page request';
	echo 'This is the first run<br>';
	die( "<a href='{$uri}?run=2'>Klick</a>" );
}

$pagerequest = filter_input( INPUT_GET, 'run', FILTER_SANITIZE_NUMBER_INT );
echo "This is the {$pagerequest}nd run with <b>{$dc->session_data}</b> from session-data";
$dc::reset();

## set_foo_example.php
<?php
function set_foo( $var ) {
	global $foo;
	$foo = $var;
}

function print_something() {
	global $foo;
	print( "Foo is {$foo}<br>" );
}

function do_something() {
	global $foo;
	$foo = (int) $foo;
	$foo++;
}

set_foo( 'Hello Bob!' );

print_something();

do_something();

global $foo;
echo 'Foo as integer: '.$foo;