PHP
downloads | documentation | faq | getting help | mailing lists | reporting bugs | php.net sites | links | conferences | my php.net

search for in the

Palavra-Chave 'final'> <Patterns
Last updated: Fri, 22 Aug 2008

view this page in

Métodos Mágicos

Os nomes de funções __construct, __destruct (veja Construtores e Destrutores), __call, __callStatic, __get, __set, __isset, __unset (veja Sobrecarga), __sleep, __wakeup, __toString, __set_state e __clone são mágicos nas classes do PHP. Você não pode ter funções com esses nomes em nenhuma de suas classes a não ser que queria que a funcionalidade mágica associada com eles.

Cuidado

PHP reserva todas as funções com nomes começando com __ como mágicas. É recomendado que você não use funções com nomes com __ no PHP a não ser que você queira alguma funcionalidade mágica documentada.

__sleep and __wakeup

serialize() checa se sua classe tem uma função com o nome mágico __sleep. Se tiver, a função é executa antes de qualquer serialização. Ela pode limpar o objeto e deve retornar um array com os nomes de todas as variáveis do objeto que devem ser serializadas. Se o método não retornar nada, então NULL é serializada e um E_NOTICE é disparado.

O intuito do método __sleep enviar dados pendentes ou realizar tarefas similares de limpeza. Além disso, a função é útil se você tiver objetos muito grandes que não precisarão ser salvos completamente.

Inversamente, unserialize() checa pela presença da função com o nome mágico __wakeup. Se achar, essa função pode reconstruir qualquer recursos que o objeto pode ter.

O intuito do método __wakeup é reestabelecer qualquer conexão com banco de dados que podem ter sido perdidas durante a serialização e realizar tarefas de reinicialização.

Exemplo #1 Sleep e wakeup

<?php
class Connection {
    protected $link;
    private $server, $username, $password, $db;

    public function __construct($server, $username, $password, $db)
    {
        $this->server = $server;
        $this->username = $username;
        $this->password = $password;
        $this->db = $db;
        $this->connect();
    }

    private function connect()
    {
        $this->link = mysql_connect($this->server, $this->username, $this->password);
        mysql_select_db($this->db, $this->link);
    }

    public function __sleep()
    {
        return array('server', 'username', 'password', 'db');
    }

    public function __wakeup()
    {
        $this->connect();
    }
}
?>

__toString

O método __toString permite que uma classe decida como se comportar quando for convertida para uma string.

Exemplo #2 Exemplo Simples

<?php
// Declara uma classe simples
class ClasseTeste
{
    public $foo;

    public function __construct($foo) {
        $this->foo = $foo;
    }

    public function __toString() {
        return $this->foo;
    }
}

$classe = new ClasseTeste('Olá');
echo $classe;
?>

O exemplo acima irá imprimir:

Olá

Vale lembrar que antes do PHP 5.2.0 o método __toString só era chamado quando diretamente combinado com echo() ou print(). Desde o PHP 5.2.0, ele é chamado no contexto de string (e.g. em printf() com modificador %s) mas não em outros tipos de contextos (e.g. como modificador %d). Desde o PHP 5.2.0, convertendo objetos sem o método __toString() para string causa E_RECOVERABLE_ERROR.

__set_state

Esse método estático é chamado para classes exportadas por var_export() desde PHP 5.1.0.

O único parâmetro para esse método é um array contendo propriedades exportadas no formato array('property' => value, ...).

Exemplo #3 Usando __set_state (desde o PHP 5.1.0)

<?php

class A
{
    public $var1;
    public $var2;

    public static function __set_state($an_array) // As of PHP 5.1.0
    {
        $obj = new A;
        $obj->var1 = $an_array['var1'];
        $obj->var2 = $an_array['var2'];
        return $obj;
    }
}

$a = new A;
$a->var1 = 5;
$a->var2 = 'foo';

eval('$b = ' . var_export($a, true) . ';'); // $b = A::__set_state(array(
                                            //    'var1' => 5,
                                            //    'var2' => 'foo',
                                            // ));
var_dump($b);

?>

O exemplo acima irá imprimir:

object(A)#2 (2) {
  ["var1"]=>
  int(5)
  ["var2"]=>
  string(3) "foo"
}


Palavra-Chave 'final'> <Patterns
Last updated: Fri, 22 Aug 2008
 
add a note add a note User Contributed Notes
Métodos Mágicos
rc @ nospam @ vorklift dot sea oh em
07-Aug-2008 04:03
A note: __wakeup occurs before saving the unserialization of an session object.

Therefore, $_SESSION['var']::__wakeup() setting $_SESSION['var'] = new Class() will fail and $_SESSION['var'] will remain unchanged.

This means that if you have a pseudo-temporary object that contains a class to auto revert to, you have to revert that session object in the initialization of the website rather than via a __wakeup() script.
Anonymous
01-Jun-2008 01:24
Serializing objects is problematic with references. This is solved redefining the __sleep() magic method. This is also problematic when parent class has private variables since the parent object is not accessible nor its private variables from within the child object.

I found a solution that seems working for classes that implements this __sleep() method, and for its subclasses. Without more work in subclasses. The inheritance system does the trick.

Recursively __sleep() call parent' __sleep() and return the whole array of variables of the object instance to be serialized.

<?php
class foo {
}

class a {
  private $var1;

  function __construct(foo &$obj = NULL) {
    $this->var1 = &$obj;
  }

  /** Return its variables array, if its parent exists and the __sleep method is accessible, call it and push the result into the array and return the whole thing. */
  public function __sleep() {
    $a = array_keys(get_object_vars(&$this));
    if (method_exists(parent, '__sleep')) {
      $p = parent::__sleep();
      array_push($a, $p);
    };
    return $a;
  }
}

class b extends a {
  function __construct(foo &$obj = NULL) {
    parent::__construct($obj);
  }
}

session_start();
$myfoo = &new foo();
$myb = &new b($myfoo);
$myb = unserialize(serialize(&$myb));
?>

This should work, I haven't tested deeper.
yanleech at gmail dot com
10-May-2008 03:24
Maybe we can using unserialize() & __wakeup() instead "new" when creating a new instance of class.

Consider following codes:

class foo
{
    static public $WAKEUP_STR = 'O:3:"foo":0:{}';
    public function foo(){}
    public function bar(){}
}

$foo = unserialize(foo::$WAKEUP_STR);
michal dot kocarek at seznam dot cz
18-Apr-2008 11:34
Remember that setters and getters (__set, __get) will work in your class as long as you NOT SET the property with given name.

If you still want to have the public property definition in the class source code (phpDocumentor, editor code completition, or any other reason) when using these magic methods, simply unset() your public properties inside the constructor.
__set/__get function will be called and code reader will see at first sight, which public properties are available.

Example:
<?php
class user {
   /**
    * @var int Gets and sets the user ID
    */
   public $UserID;
   private $_userID;

   public function __construct() {

      // All the magic is in single line:
      // We unset public property, so our setters and getters
      // are used and phpDoc and editors with code completition are happy
      unset($this->UserID);

   }

   public function __set($key, $value) {
      // assign value for key UserID to _userID property
   }

   public function __get($key) {
      // return value of _userID for UserID property
   }
}
?>
dhuseby domain getback tld com
01-Mar-2008 03:22
The above hint for using array_keys((array)$obj) got me investigating how to get __sleep to really work with object hierarchies.

With PHP 5.2.3, If you want to serialize an object that is part of an object hierarchy and you want to selectively serialize members (public, private, and protected) by manually specifying the array of members, there are a few simple rules for naming members that you must follow:

1. public members should be named using just their member name, like so:

<?php
class Foo {
    public $bar;

    public function __sleep() {
        return array("bar");
    }
}
?>

2. protected members should be named using "\0" . "*" . "\0" . member name, like so:

<?php
class Foo {
    protected $bar;

    public function __sleep() {
        return array("\0*\0bar");
    }
}
?>

3. private members should be named using "\0" . class name . "\0" . member name, like so:

<?php
class Foo {
    private $bar;

    public function __sleep() {
        return array("\0Foo\0bar");
    }
}
?>

So with this information let us serialize a class hierarchy correctly:

<?php

class Base {
    private $foo = "foo_value";
    protected $bar = "bar_value";

    public function __sleep() {
        return array("\0Base\0foo", "\0*\0bar");
    }
}

class Derived extends Base {
    public $baz = "baz_value";
    private $boo = "boo_value";

    public function __sleep() {
        // we have to merge our members with our parent's
        return array_merge(array("baz", "\0Derived\0boo"), parent::__sleep());
    }
}

class Leaf extends Derived {
    private $qux = "qux_value";
    protected $zaz = "zaz_value";
    public $blah = "blah_value";

    public function __sleep() {
        // again, merge our members with our parent's
        return array_merge(array("\0Leaf\0qux", "\0*\0zaz", "blah"), parent::__sleep());
    }
}

// test it
$test = new Leaf();
$s = serialize($test);
$test2 = unserialize($s);
echo $s;
print_r($test);
print_r($test2);

?>

Now if you comment out all of the __sleep() functions and output the serialized string, you will see that the output doesn't change.  The most important part of course is that with the proper __sleep() functions, we can unserialize the string and get a properly set up object.

I hope this solves the mystery for everybody.  __sleep() does work, if you use it correctly :-)
andrew dot minerd at sellingsource dot com
08-Nov-2007 04:55
Until __sleep is "fixed" (here's hoping), a function that will return ALL members of a given object -- public, protected, AND private:

<?php
        public function getPropertyNames(array $filter = NULL)
        {
            $rc = new ReflectionObject($this);
            $names = array();

            while ($rc instanceof ReflectionClass)
            {
                foreach ($rc->getProperties() as $prop)
                {
                    if (!$filter || !in_array($prop->getName(), $filter))
                        $names[] = $prop->getName();
                }

                $rc = $rc->getParentClass();
            }

            return $names;
        }
?>
amir_abiri at ipcmedia dot com
24-Jul-2007 01:58
Another small thing that is important to note about __sleep() and privte member variables:

<?php
class A
{
  private $a;
 
  public function __construct()
  {
    $this->a = 1;
  }
}

class B extends A
{
  protected $b;
 
  public function __construct()
  {
    parent::__construct();
    $this->b = 2;
  }
 
  function __sleep()
  {
    return array('a', 'b');
  }
}

serialize(new B);
?>

result:
Notice: serialize(): "a" returned as member variable from __sleep() but does not exist in ...

To summerize: in a given class hierarchy in which parent classes contain private member variables, those variables are serialized when __sleep() is not defined. However, once __sleep() is defined, there is no way to make those private member variables serialized as well. From that point on, serialization is performed from the visibility scope of the subclass.

It is particularly important to note this little quirk when designing base classes that their derivables may be serialized, or when subclassing an external library class.
alejandro dot gama at gmail dot com
09-May-2007 04:47
Referering my previus note: there was an error in the code. But i find a better way:

<?
session_start();

class Classes{
  private $name;
  private $statics;
   
  function __construct($name){
    $this->name=$name;
    $this->statics=array();
  }
   
  function setStatic($k,$v){
    if(!is_resource($v))
      $this->statics[$k]=$v;
  }
   
   
  function __wakeup(){
    foreach($this->statics as $k=>$v)
      eval($this->name."::\$".$k."=\$this->statics['".$k."'];");
  }
}

function storeStaticAttributes(){
  $classes=get_declared_classes();
  foreach($classes as $name){
    $reflect=new ReflectionClass($name);

    if($reflect->isUserDefined()){
      $statics=$reflect->getStaticProperties();

      if(empty($_SESSION["_classes"]))
        $_SESSION["_classes"]=array();
           
      if(empty($_SESSION["_classes"][$name]))
        $_SESSION["_classes"][$name]=new Classes($name);

      foreach($statics as $k=>$v)
        $_SESSION["_classes"][$name]->setStatic($k,$v);   
    }
  }
}
register_shutdown_function('storeStaticAttributes');
?>
Travis Swicegood
08-May-2007 04:43
There is no need to use eval() to mimic mixins (i.e., multiple inheritance) within PHP 5.  You only need to:

<?php

class MyClass
{
    private $_obj = null;
    public function __construct($obj)
    {
        $this->_obj = $obj;
    }

    public function __call($method, $args)
    {
        if (!method_exists($this->_obj, $method)) {
            throw new Exception("unknown method [$method]");
        }

        return call_user_func_array(
            array($this->_obj, $method),
            $args
        );
    }
}

?>

You could just as easily add an addMixin() method that would allow you to add multiple objects to an array, and then iterate over that array until you found the right method.  As noted, these are referred to as a Mixins in other languages.
adar at darkpoetry dot de
05-May-2007 03:09
Maybe not really new and all in all definitely not the best solution,but if you cant extend a class (if your class alreay extends an abstract or other things like that) you can 'fake' a extend.

<?php
class MyClass
        extends SomeAbstractUnknownClass {

    private $classObject;

    public function __construct ( classObject $classToExtend ) {
        $this->classObject = $classToExtend;
    }

    public function __call($func, $var) {
        if ( !count($var) ) {
            return $this->classObject->$func($var);
        } else {
            $str = '';
            $values = array_values($var);
            for ( $i=0; $i<count($values); $i++ ) {
                $str .= "'".$values[$i]."' ,";
            }  
            $str = substr($str, 0, -2);
            return eval('return $this->classObject->'.$func.'('.$str.');');
        }  
    }  
}
?>

So if you'll do a $myClass->unknownMethod() and it is found neither in MyClass nor in SomeAbstractUnknownClass, MyClass will try to call this method in $classObject.

I use this for 'extending' a UserObject-Class which already extends an other one.

Better solutions are always welcome ;)
Dérico Filho
23-Jan-2007 04:33
Since PHP 5.2.0, you'll always get an error like this:
"Object of class foo could not be converted to string"

When one tries to use an object as string, for instance:

class Test{}
echo new Test();

Thus, one way to avoid this problem is to programme the magic method __toString.

However, in the older versions, it would output a string saying that it was an object together a unique obj id. Therefore, the __toString() method must comply with this behaviour.

My suggestion:

class Test{
    function __toString(){
        if(!isset($this->__uniqid))
            $this->__uniqid = md5(uniqid(rand(), true));
        return(get_class($this)."@".$this->__uniqid);
    }

}

echo new Test();

would output something like this:

Test@6006ba04f5569544c10a588b04849cf7
jstubbs at work-at dot co dot jp
02-Sep-2006 09:32
$myclass->foo['bar'] = 'baz';

When overriding __get and __set, the above code can work (as expected) but it depends on your __get implementation rather than your __set. In fact, __set is never called with the above code. It appears that PHP (at least as of 5.1) uses a reference to whatever was returned by __get. To be more verbose, the above code is essentially identical to:

$tmp_array = &$myclass->foo;
$tmp_array['bar'] = 'baz';
unset($tmp_array);

Therefore, the above won't do anything if your __get implementation resembles this:

function __get($name) {
    return array_key_exists($name, $this->values)
        ? $this->values[$name] : null;
}

You will actually need to set the value in __get and return that, as in the following code:

function __get($name) {
    if (!array_key_exists($name, $this->values))
        $this->values[$name] = null;
    return $this->values[$name];
}
taylorbarstow at google's mail service
15-May-2006 10:54
I've just come accross something interesting relating to storing PHP5 objects in a session.  If you don't provide an __autoload(), then you MUST load the class definition before calling session_start().  I guess that when you call session_start(), any objects in the session are unserialized then and there and placed into $_SESSION.  If you don't provide the class definition before calling session_start(), your object will get the class __PHP_Incomplete_Class, and you won't be able to use it for anything.

Examples:

<?php
session_start();
require_once 'MyClass.php';
$obj = new MyClass;
$_SESSION['obj'] = $obj;
?>

Works fine.  Then on a subsequent page load:

<?php
session_start();
require_once 'MyClass.php';
$_SESSION['obj']->callSomeMethod();
?>

Fatal error:  The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "MyClass" of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition.

But if you do this instead, it works fine:

<?php
require_once 'MyClass.php';
session_start();
$_SESSION['obj']->callSomeMethod();
?>

Hopefully in some future release of PHP, __PHP_Incomplete_Class will be smart enough to check for a class definition at time of use (method call or property operation), and, if the class exists, magically "complete" itself and turn into the desired object.
rayRO
02-Apr-2006 06:55
If you use the Magical Method '__set()', be shure that the call of
<?php
$myobject->test['myarray'] = 'data';
?>
will not appear!

For that u have to do it the fine way if you want to use __set Method ;)
<?php
$myobject->test = array('myarray' => 'data');
?>

If a Variable is already set, the __set Magic Method already wont appear!

My first solution was to use a Caller Class.
With that, i ever knew which Module i currently use!
But who needs it... :]
There are quiet better solutions for this...
Here's the Code:

<?php
class Caller {
    public $caller;
    public $module;

    function __call($funcname, $args = array()) {
        $this->setModuleInformation();

        if (is_object($this->caller) && function_exists('call_user_func_array'))
            $return = call_user_func_array(array(&$this->caller, $funcname), $args);
        else
            trigger_error("Call to Function with call_user_func_array failed", E_USER_ERROR);
       
        $this->unsetModuleInformation();
        return $return;
    }

    function __construct($callerClassName = false, $callerModuleName = 'Webboard') {
        if ($callerClassName == false)
            trigger_error('No Classname', E_USER_ERROR);

        $this->module = $callerModuleName;

        if (class_exists($callerClassName))
            $this->caller = new $callerClassName();
        else
            trigger_error('Class not exists: \''.$callerClassName.'\'', E_USER_ERROR);

        if (is_object($this->caller))
        {
            $this->setModuleInformation();
            if (method_exists($this->caller, '__init'))
                $this->caller->__init();
            $this->unsetModuleInformation();
        }
        else
            trigger_error('Caller is no object!', E_USER_ERROR);
    }

    function __destruct() {
        $this->setModuleInformation();
        if (method_exists($this->caller, '__deinit'))
            $this->caller->__deinit();
        $this->unsetModuleInformation();
    }

    function __isset($isset) {
        $this->setModuleInformation();
        if (is_object($this->caller))
            $return = isset($this->caller->{$isset});
        else
            trigger_error('Caller is no object!', E_USER_ERROR);
        $this->unsetModuleInformation();
        return $return;
    }

    function __unset($unset) {
        $this->setModuleInformation();
        if (is_object($this->caller)) {
            if (isset($this->caller->{$unset}))
                unset($this->caller->{$unset});
        }
        else
            trigger_error('Caller is no object!', E_USER_ERROR);
        $this->unsetModuleInformation();
    }

    function __set($set, $val) {
        $this->setModuleInformation();
        if (is_object($this->caller))
            $this->caller->{$set} = $val;
        else
            trigger_error('Caller is no object!', E_USER_ERROR);
        $this->unsetModuleInformation();
    }

    function __get($get) {
        $this->setModuleInformation();
        if (is_object($this->caller)) {
            if (isset($this->caller->{$get}))
                $return = $this->caller->{$get};
            else
                $return = false;
        }
        else
            trigger_error('Caller is no object!', E_USER_ERROR);
        $this->unsetModuleInformation();
        return $return;
    }
   
    function setModuleInformation() {
        $this->caller->module = $this->module;
    }

    function unsetModuleInformation() {
        $this->caller->module = NULL;
    }
}

// Well this can be a Config Class?
class Config {
    public $module;

    public $test;

    function __construct()
    {
        print('Constructor will have no Module Information... Use __init() instead!<br />');
        print('--> '.print_r($this->module, 1).' <--');
        print('<br />');
        print('<br />');
        $this->test = '123';
    }
   
    function __init()
    {
        print('Using of __init()!<br />');
        print('--> '.print_r($this->module, 1).' <--');
        print('<br />');
        print('<br />');
    }
   
    function testFunction($test = false)
    {
        if ($test != false)
            $this->test = $test;
    }
}

echo('<pre>');
$wow = new Caller('Config', 'Guestbook');
print_r($wow->test);
print('<br />');
print('<br />');
$wow->test = '456';
print_r($wow->test);
print('<br />');
print('<br />');
$wow->testFunction('789');
print_r($wow->test);
print('<br />');
print('<br />');
print_r($wow->module);
echo('</pre>');
?>

Outputs something Like:

Constructor will have no Module Information... Use __init() instead!
-->  <--

Using of __init()!
--> Guestbook <--

123

456

789

Guestbook
ksamvel at gmail dot com
10-Feb-2006 06:29
To copy base part of derived class appropriate method in base should be defined. E.g.:

  class A {
    public function setAVar( $oAVar) { $this->oAVar = $oAVar; }
    public function getAVar() { return $this->oAVar; }

    public function copyA( &$roDest) {
      if( $roDest instanceof A)
        $this->oAVar = $roDest->oAVar;
    }

    private $oAVar;
  }

  class B extends A {
    public function setBVar( $oBVar) { $this->oBVar = $oBVar; }
    public function getBVar() { return $this->oBVar; }

    private $oBVar;
  }

  $oA = new A();
  $oB = new B();

  $oA->setAVar( 4);

  $oB->setAVar( 5);
  $oB->setBVar( 6);
  echo "oA::oAVar " . $oA->getAVar() . "<br>";
  echo "oB::oAVar " . $oB->getAVar() . "<br>";
  echo "oB::oBVar " . $oB->getBVar() . "<br>";
  echo "<br>";

  $oB->copyA( $oA);

  echo "oA::oAVar " . $oA->getAVar() . "<br>";
  echo "oB::oAVar " . $oB->getAVar() . "<br>";
  echo "oB::oBVar " . $oB->getBVar() . "<br>";

Output:

oA::oAVar 4
oB::oAVar 5
oB::oBVar 6

oA::oAVar 4
oB::oAVar 4
oB::oBVar 6
b dot schoppmeier at bas-consult dot de
26-Jan-2006 12:18
The sequence of events regarding __sleep and __destruct is unusual __ as __destruct is called before __sleep. The following code snippet:

<?php
$sequence = 0;
class foo {
    public $stuff;   
    public function __construct($param) {
        global $sequence;
        echo "Seq: ", $sequence++, " - constructor\n";
        $this->stuff = $param;
    }
    public function __destruct() {
        global $sequence;
        echo "Seq: ", $sequence++, " - destructor\n";
    }
    public function __sleep() {
        global $sequence;
        echo "Seq: ", $sequence++, " - __sleep\n";
        return array("stuff");
    }
    public function __wakeup() {
        global $sequence;
        echo "Seq: ", $sequence++, " - __wakeup\n";
    }
}
session_start();
$_SESSION["obj"] = new foo("A foo");
?>

yields the output:

Seq: 0 - constructor
Seq: 1 - destructor
Seq: 2 - __sleep

Only when you end your script with a call to session_write_close() as in:

<?php
$sequence = 0;
class foo {
    public $stuff;   
    public function __construct($param) {
        global $sequence;
        echo "Seq: ", $sequence++, " - constructor\n";
        $this->stuff = $param;
    }
    public function __destruct() {
        global $sequence;
        echo "Seq: ", $sequence++, " - destructor\n";
    }
    public function __sleep() {
        global $sequence;
        echo "Seq: ", $sequence++, " - __sleep\n";
        return array("stuff");
    }
    public function __wakeup() {
        global $sequence;
        echo "Seq: ", $sequence++, " - __wakeup\n";
    }
}
session_start();
$_SESSION["obj"] = new foo("A foo");
session_write_close();
?>

the sequence is as common sense would expect it to be as the following output shows:

Seq: 0 - constructor
Seq: 1 - __sleep
Seq: 2 - destructor
docey
09-Dec-2005 05:44
about __sleep and _wakeup, consider using a method like this:

class core
{

 var $sub_core; //ref of subcore
 var $_sleep_subcore; // place where serialize version of sub_core will be stored

 function core(){
  $this->sub_core = new sub_core();
  return true;
 }

 function __wakeup()
 {
  // on wakeup of core, core unserializes sub_core
  // wich it had stored when it was serialized itself
  $this->sub_core = unserialize($this->_sleep_subcore);
  return true;
 }

 function __sleep()
 {
  // sub_core will be serialized when core is serialized.
  // the serialized subcore will be stored as a string inside core.
   $this->_sleep_subcore = serialize($this->sub_core);
   $return_arr[] = "_sleep_subcore";
   return $return_arr;
 }

}

class sub_core
{
 var $info;

 function sub_core()
 {
  $this->info["somedata"] = "somedata overhere"
 }

 function __wakeup()
 {
  return true;
 }

 function __sleep()
 {
  $return_arr[] = "info"
  return $return_arr;
 }

}

this way subcore is being serialized by core when core is being serialized. subcore handles its own data and core stores it as a serialize string inside itself. on wakeup core unserializes subcore.

this may have a performance cost, but if you have many objects connected this way this is the best way of serializing them. you only need to serialize the the main object wich will serialize all those below which will serialize all those below them again. in effect causing a sort of chainreaction in wich each object takes care of its own info.

offcoarse you always need to store the eventualy serialized string in a safe place. somebody got experience with this way of __wakeup and __sleep.

works in PHP4&5
martin dot goldinger at netserver dot ch
15-Aug-2005 01:47
When you use sessions, its very important to keep the sessiondata small, due to low performance with unserialize. Every class shoud extend from this class. The result will be, that no null Values are written to the sessiondata. It will increase performance.

<?
class BaseObject
{
    function __sleep()
    {
        $vars = (array)$this;
        foreach ($vars as $key => $val)
        {
            if (is_null($val))
            {
                unset($vars[$key]);
            }
        }   
        return array_keys($vars);
    }
};
?>
jeffxlevy at gmail dot com
14-Aug-2005 03:26
Intriguing what happens when __sleep() and __wakeup() and sessions() are mixed. I had a hunch that, as session data is serialized, __sleep would be called when an object, or whatever, is stored in _SESSION. true. The same hunch applied when session_start() was called. Would __wakeup() be called? True. Very helpful, specifically as I'm building massive objects (well, lots of simple objects stored in sessions), and need lots of automated tasks (potentially) reloaded at "wakeup" time. (for instance, restarting a database session/connection).
mastabog at hotmail dot com
13-Aug-2005 02:06
In reply to krisj1010 at gmail.com below:

__sleep() handles protected/private properties very well. You should never rely on get_class_vars() to retrieve property names since this function only returns the public properties. Use the Reflection API instead for that purpose. Better yet, if you know which ones you want to save it is always faster to specify the return array manually.
Domenic Denicola
23-Jun-2005 05:52
This small sentence tripped me up for a half an hour:

"It is worth noting that the __toString method will only be called when it is directly combined with echo() or print()."

So code like this will _not_ work, even though you might think it would:

<?

//$x is some variable with a __toString method defined.
$y = "x's value is: " . $x;
$y = "x's value is: " . (string)$x;

?>

In _em_ both situations, $y will contain "x's value is: Object id #42" (or whatever object ID). So, the only recourse I guess is this:

<?

$y = "x's value is: " . $x->__toString();

?>
elias
11-Apr-2005 06:48
The default toString output is very useful for visual debuggin
because it shows the object id.
There is no function to resolve the id directly(?), but you
can do this:

<?php
function __toString()
{
    sscanf((string)$this, "Object id #%d", $id);
    return "Object(Template) id #$id";
}
?>

HTH,
elias
ddavenport at newagedigital dot com
27-Jan-2005 08:09
One of the principles of OOP is encapsulation--the idea that an object should handle its own data and no others'.  Asking base classes to take care of subclasses' data, esp considering that a class can't possibly know how many dozens of ways it will be extended, is irresponsible and dangerous.

Consider the following...

<?php
class SomeStupidStorageClass
{
  public function getContents($pos, $len) { ...stuff... }
}

class CryptedStorageClass extends SomeStupidStorageClass
{
  private $decrypted_block;
  public function getContents($pos, $len) { ...decrypt... }
}
?>

If SomeStupidStorageClass decided to serialize its subclasses' data as well as its own, a portion of what was once an encrypted thingie could be stored, in the clear, wherever the thingie was stored.  Obviously, CryptedStorageClass would never have chosen this...but it had to either know how to serialize its parent class's data without calling parent::_sleep(), or let the base class do what it wanted to.

Considering encapsulation again, no class should have to know how the parent handles its own private data.  And it certainly shouldn't have to worry that users will find a way to break access controls in the name of convenience.

If a class wants both to have private/protected data and to survive serialization, it should have its own __sleep() method which asks the parent to report its own fields and then adds to the list if applicable.  Like so....

<?php

class BetterClass
{
  private $content;

  public function __sleep()
  {
    return array('basedata1', 'basedata2');
  }

  public function getContents() { ...stuff... }
}

class BetterDerivedClass extends BetterClass
{
  private $decrypted_block;

  public function __sleep()
  {
    return parent::__sleep();
  }

  public function getContents() { ...decrypt... }
}

?>

The derived class has better control over its data, and we don't have to worry about something being stored that shouldn't be.
krisj1010 at gmail.com
09-Jan-2005 09:09
If you are attempting to write an abstract/base class which automates the __sleep process in PHP5 you will run into some trouble if the subclasses which are being serialized have private/protected variables you need to be serialized. 

The reason is, even though get_class($this) within the base class will return the subclass -- get_class_vars(get_class($this)) will *not* return the subclass' protected/private variables.  Which makes sense -- using OO principles. 

However, when automating __sleep it becomes necissary to have access to the private/protected subclass variables because their names have to be returned by __sleep.

So here is the work around:
<?php
public function __sleep()
{
 ... code ...
$sleepVars    = array_keys((array)$this);
return $sleepVars;
}
?>

Even though array_keys includes more information about the variable names than just the variable names -- it still seems to work appropriately.
add a note add a note

Palavra-Chave 'final'> <Patterns
Last updated: Fri, 22 Aug 2008
 
 
show source | credits | sitemap | contact | advertising | mirror sites