オブジェクト インターフェイス
Combining two things noted previously:
1 - Unsetting an object member removes it from the object completely, subsequent uses of that member will be handled by magic methods.
2 - PHP will not recursively call one magic method from within itself (at least for the same $name).
This means that if an object member has been unset(), it IS possible to re-declare that object member (as public) by creating it within your object's __set() method, like this:
<?php
class Foo
{
function __set($name, $value)
{
// Add a new (public) member to this object.
// This works because __set() will not recursively call itself.
$this->$name= $value;
}
}
$foo = new Foo();
// $foo has zero members at this point
var_dump($foo);
// __set() will be called here
$foo->bar = 'something'; // Calls __set()
// $foo now contains one member
var_dump($foo);
// Won't call __set() because 'bar' is now declared
$foo->bar = 'other thing';
?>
Also be mindful that if you want to break a reference involving an object member without triggering magic functionality, DO NOT unset() the object member directly. Instead use =& to bind the object member to any convenient null variable.
オーバーロード
PHP におけるオーバーロード機能は、 プロパティやメソッドを動的に "作成する" ための手法です。 これらの動的エンティティは、マジックメソッドを用いて処理されます。 マジックメソッドは、クラス内でさまざまなアクションに対して用意することができます。
オーバーロードメソッドが起動するのは、 宣言されていないプロパティやメソッドを操作しようとしたときです。 また、現在のスコープからは アクセス不能な プロパティやメソッドを操作しようとしたときにも起動します。 このセクションでは、これらの (宣言されていない、 あるいは現在のスコープからはアクセス不能な) プロパティやメソッドのことを "アクセス不能プロパティ" および "アクセス不能メソッド" と表記することにします。
オーバーロードメソッドは、すべて public で定義しなければなりません。
注意: これらのマジックメソッドの引数は、 参照渡し とすることはできません。
注意: PHP における "オーバーロード" の解釈は、他の多くのオブジェクト指向言語とは異なります。 一般的に「オーバーロード」とは、 「名前は同じだけれども引数の数や型が異なるメソッドを複数用意できる」 という機能のことを指します。
変更履歴
| バージョン | 説明 |
|---|---|
| 5.3.0 | __callStatic() が追加されました。 public で、かつ static でない宣言を強制するような警告が追加されました。 |
| 5.1.0 | __isset() と __unset() が追加されました。 |
プロパティのオーバーロード
bool __isset
( string $name
)
void __unset
( string $name
)
__set() は、 アクセス不能プロパティへデータを書き込む際に実行されます。
__get() は、 アクセス不能プロパティからデータを読み込む際に使用します。
__isset() は、 isset() あるいは empty() をアクセス不能プロパティに対して実行したときに起動します。
__unset() は、 unset() をアクセス不能プロパティに対して実行したときに起動します。
引数 $name は、 操作しようとしたプロパティの名前です。 __set() メソッドの引数 $value は、 $name に設定しようとした値となります。
プロパティのオーバーロードはオブジェクトのコンテキストでのみ動作します。 これらのマジックメソッドは、静的コンテキストでは起動しません。 したがって、これらのメソッドは static 宣言することはできません。
注意: __set() の返り値は無視されます。 これは、PHP が代入演算子を処理する方法によるものです。 同様に __get() は、
のように代入と連結した場合には決してコールされません。$a = $obj->b = 8;
例1 __get()、 __set()、__isset() および __unset() メソッドを使ったプロパティのオーバーロードの例
<?php
class PropertyTest {
/** オーバーロードされるデータの場所 */
private $data = array();
/** 宣言されているプロパティにはオーバーロードは起動しません */
public $declared = 1;
/** クラスの外部からアクセスした場合にのみこれがオーバーロードされます */
private $hidden = 2;
public function __set($name, $value) {
echo "Setting '$name' to '$value'\n";
$this->data[$name] = $value;
}
public function __get($name) {
echo "Getting '$name'\n";
if (array_key_exists($name, $this->data)) {
return $this->data[$name];
}
$trace = debug_backtrace();
trigger_error(
'Undefined property via __get(): ' . $name .
' in ' . $trace[0]['file'] .
' on line ' . $trace[0]['line'],
E_USER_NOTICE);
return null;
}
/** PHP 5.1.0 以降 */
public function __isset($name) {
echo "Is '$name' set?\n";
return isset($this->data[$name]);
}
/** PHP 5.1.0 以降 */
public function __unset($name) {
echo "Unsetting '$name'\n";
unset($this->data[$name]);
}
/** マジックメソッドではありません。単なる例として示しています */
public function getHidden() {
return $this->hidden;
}
}
echo "<pre>\n";
$obj = new PropertyTest;
$obj->a = 1;
echo $obj->a . "\n\n";
var_dump(isset($obj->a));
unset($obj->a);
var_dump(isset($obj->a));
echo "\n";
echo $obj->declared . "\n\n";
echo "Let's experiment with the private property named 'hidden':\n";
echo "Privates are visible inside the class, so __get() not used...\n";
echo $obj->getHidden() . "\n";
echo "Privates not visible outside of class, so __get() is used...\n";
echo $obj->hidden . "\n";
?>
上の例の出力は以下となります。
Setting 'a' to '1' Getting 'a' 1 Is 'a' set? bool(true) Unsetting 'a' Is 'a' set? bool(false) 1 Let's experiment with the private property named 'hidden': Privates are visible inside the class, so __get() not used... 2 Privates not visible outside of class, so __get() is used... Getting 'hidden' Notice: Undefined property via __get(): hidden in <file> on line 70 in <file> on line 29
メソッドのオーバーロード
__call() は、 アクセス不能メソッドをオブジェクトのコンテキストで実行したときに起動します。
__callStatic() は、 アクセス不能メソッドを静的コンテキストで実行したときに起動します。
引数 $name は、 コールしようとしたメソッドの名前です。 引数 $arguments は配列で、メソッド $name に渡そうとしたパラメータが格納されます。
例2 __call() および __callStatic() メソッドによる、メソッドのオーバーロードの例
<?php
class MethodTest {
public function __call($name, $arguments) {
// 注意: $name は大文字小文字を区別します
echo "Calling object method '$name' "
. implode(', ', $arguments). "\n";
}
/** PHP 5.3.0 以降 */
public static function __callStatic($name, $arguments) {
// 注意: $name は大文字小文字を区別します
echo "Calling static method '$name' "
. implode(', ', $arguments). "\n";
}
}
$obj = new MethodTest;
$obj->runTest('in object context');
MethodTest::runTest('in static context'); // PHP 5.3.0 以降
?>
上の例の出力は以下となります。
Calling object method 'runTest' in object context Calling static method 'runTest' in static context
add a note
User Contributed Notesオーバーロード
strata_ranger at hotmail dot com
07-Oct-2009 04:56
07-Oct-2009 04:56
Franz
05-Oct-2009 05:59
05-Oct-2009 05:59
It says in the documentation that assignment chaining does not work with the __set() function like this:
<?php
$a = $foo->b = 3;
?>
If you still want to make it work, I suppose you can just turn the variables around:
<?php
$foo->b = $a = 3;
?>
kexianbin at diyism dot com
21-Aug-2009 06:29
21-Aug-2009 06:29
By using __call, we can use php as using jQuery:
<?php
//SoWork PHP Framework
define('this', mt_rand());
$o='so_work';
class cls_so_work
{function __call($fun, $pars)
{foreach ($pars as &$v)
{if ($v===this)
{$v=$this->val;
break;
}
}
$tmp=eval('return defined("'.$fun.'")?constant("'.$fun.'"):"'.$fun.'";');
$this->val=call_user_func_array($tmp, $pars);
return $this;
}
function cls_so_work($obj)
{$this->val=isset($obj)?$obj:null;
}
}
function so_work($obj)
{if (isset($obj))
{return new cls_so_work($obj);
}
else
{if (!isset($GLOABALS['so_work']))
{$GLOABALS['so_work']=new cls_so_work();
}
else
{$GLOABALS['so_work']->val=null;
}
return $GLOABALS['so_work'];
}
}
define('echo', 'my_echo');
function my_echo($obj)
{echo $obj;
return $obj;
}
$o('abcd')->substr(this, 2, 2)->strlen(this)->echo(this);
$o()->substr('abcd', 1, 3)->strlen(this)->echo(this);
?>
eric dot druid+php dot net at gmail dot com
01-Jul-2009 11:22
01-Jul-2009 11:22
I needed to know from where a member variable was set from to determine visibility.
<?php
class foo {
private $data;
public function __set($name, $value) {
$trace = debug_backtrace();
if(!isset($trace[1]) || $trace[1]['object'] != $trace[0]['object']) {
die("Trying to set protected member '$name' from public scope.");
}
$data[$name] = $value;
}
}
?>
Anonymous
05-Jun-2009 10:54
05-Jun-2009 10:54
It is possible to accomplish method polymorphism via PHP's __call method:
<?php
class Example{
public function __call($name, $arguments){
switch($name){
case 'foo':
switch(count($arguments)){
case 2:
echo 'You called "foo" with two arguments.<br>' . PHP_EOL;
break;
case 3:
echo 'You called "foo" with three arguments.<br>' . PHP_EOL;
break;
default:
echo 'Error: Invalid number of arguments to "foo."<br>' . PHP_EOL;
break;
}
break;
default:
echo "Error: Call to undefined function \"$name.\"<br>" . PHP_EOL;
}
}
}
$test = new Example;
$test->foo('bar', 'baz');
$test->foo('bar', 'baz', 'fez', 'fap');
$test->bar();
?>
troggy dot brains at gmx dot de
19-May-2009 07:17
19-May-2009 07:17
Just another note about using __get() & __set() on array properties with PHP v5.2.0.
Took me quite a while to find out why I couldn't write an array property that was created via __set(). Now a few notes earlier someone described a working solution using the ArrayObject-class. This does work, but has a big downside, you cannot expect other programmers to know that they will be getting an instance of ArrayObject instead of a native array, and trying to do an implode() on an ArrayObject will just not work. So, here is my solution to the problem:
<?php
class A {
private $properties = array();
public function __set($key, $value) {
if (is_array($value)) {
$this->$key = $value;
} else {
$this->properties[$key] = $value;
}
}
public function __get($key) {
if (array_key_exists($key, $this->properties)) {
return $this->properties[$key];
}
return null;
}
}
?>
The idea behind this is, that you can register new properties at any time from within a class without getting a warning or some of that kind. Now, if you try to set a property from outside the class, the __set() method will be called and decides whether to place the new property in the properties array or declare it as a new "native" property. When trying to get that property, the __get() method will only be called if the property is not "native", which won't be the case for an array.
HTH
daevid at daevid dot com
15-May-2009 04:16
15-May-2009 04:16
Here's a handy little routine to suggest properties you're trying to set that don't exist. For example:
Attempted to __get() non-existant property/variable 'operator_id' in class 'User'.
checking for operator and suggesting the following:
* id_operator
* operator_name
* operator_code
enjoy.
<?php
/**
* Suggests alternative properties should a __get() or __set() fail
*
* @param string $property
* @return string
* @author Daevid Vincent [daevid@daevid.com]
* @date 05/12/09
* @see __get(), __set(), __call()
*/
public function suggest_alternative($property)
{
$parts = explode('_',$property);
foreach($parts as $i => $p) if ($p == '_' || $p == 'id') unset($parts[$i]);
echo 'checking for <b>'.implode(', ',$parts)."</b> and suggesting the following:<br/>\n";
echo "<ul>";
foreach($this as $key => $value)
foreach($parts as $p)
if (stripos($key, $p) !== false) print '<li>'.$key."</li>\n";
echo "</ul>";
}
just put it in your __get() or __set() like so:
public function __get($property)
{
echo "<p><font color='#ff0000'>Attempted to __get() non-existant property/variable '".$property."' in class '".$this->get_class_name()."'.</font><p>\n";
$this->suggest_alternative($property);
exit;
}
?>
niehztog
14-Feb-2009 06:59
14-Feb-2009 06:59
If you got a parent class agregating(not inheriting) a number of child classes in an array, you can use the following to allow calling methods of the parent object on agregated child objects:
<?php
class child {
public $holder = null;
public function __call($name, $arguments) {
if($this->holder instanceof parentClass && method_exists($this->holder, $name)) {
return call_user_func_array(array($this->holder, $name), $arguments);
}
else {
trigger_error();
}
}
}
class parentClass {
private $children = array();
function __construct() {
$this->children[0] = new child();
$this->children[0]->holder = $this;
}
function getChild($number) {
if(!isset($this->children[$number])) {
return false;
}
return $this->children[$number];
}
function test() {
return 'it works';
}
}
$parent = new parentClass();
$firstChild = $parent->getChild(0);
echo $firstChild->test(); //should output 'it works'
?>
jorge dot hebrard at gmail dot com
24-Dec-2008 12:55
24-Dec-2008 12:55
This is a great way to give different permissions to parent classes.
<?php
class A{
private $b;
function foo(){
$this->b = new B;
echo $this->b->protvar;
}
}
class B extends A{
protected $protvar="protected var";
public function __get($nm) {
echo "Default $nm value";
}
}
$a = new A;
$b = new B;
$a->foo(); // prints "protected var"
echo $b->protvar; // prints "Default protvar value"
?>
This way, you can help parent classes to have more power with protected members.
Ant P.
21-Dec-2008 04:40
21-Dec-2008 04:40
Be extra careful when using __call(): if you typo a function call somewhere it won't trigger an undefined function error, but get passed to __call() instead, possibly causing all sorts of bizarre side effects.
In versions before 5.3 without __callStatic, static calls to nonexistent functions also fall through to __call!
This caused me hours of confusion, hopefully this comment will save someone else from the same.
erick2711 at gmail dot com
14-Nov-2008 03:33
14-Nov-2008 03:33
<?php
/***********************************************
*And here follows a child class which implements a menu based in the 'nodoMenu' class (previous note).
*
*[]s
*
*erick2711 at gmail dot com
************************************************/
class menu extends nodoMenu{
private $cssc = array();
public function __toString(){ //Just to show, replace with something better.
$stringMenu = "<pre>\n";$stringMenu .= $this->strPrint();$stringMenu .= "</pre>\n";
return $stringMenu;
}
public function __construct($cssn = null){
parent::__construct();
if (isset($cssn) && is_array($cssn)){$this->cssc = $cssn;}
$this->buildMenu();
}
public function buildMenu(){
$this->add('server',
'Server',
'server.php');
$this->server->add('personalD',
'Personal Data',
'server/personal.php');
$this->server->add('personalI',
'Personal Interviews',
'server/personalI.php');
$this->server->personalI->add('detailsByIer',
'Detalis by Interviewer',
'server/personalI.php?tab=detailsByIer');
//(...)
return $this;
}
}
//Testing
$meuMenu = new menu;
echo $meuMenu;
/***********************************************
*Will output (to the browser):
*
*<pre>
*1 Server<br>
* 1.1 Personal Data<br>
* 1.2 Personal Interviews<br>
* 1.2.1 Details by Interviewer<br>
*</pre>
*
*Which shows:
*
*1 Server
* 1.1 Personal Data
* 1.2 Personal Interviews
* 1.2.1 Details by Interviewer
************************************************/
?>
erick2711 at gmail dot com
14-Nov-2008 03:09
14-Nov-2008 03:09
<?php
/*
Here folows a little improvement of the 'strafvollzugsbeamter at gmx dot de' code, allowing each node to hold both 'parameters' and 'child nodes', and differentiate $s->A->B->C ('FOO') from $s->A (same 'FOO', but shouldn't exist) and from $s-A->B (idem).
This allows the class, using the interesting suggested syntax ($root->dad->child->attribute, in which 'dad's and 'child's names are dynamically generated), to do something actually useful, like implementing a n-tree data structure (a menu, for instance).
It was tested under PHP 5.2.6 / Windows.
I know that must there be something better which already do this (probably in the DOM Model classes, or something like), but it was fun to develop this one, for the sake of studying the "magic" methods.
Its a compressed version of the code (no comments, too short variable names, almost no identation). I had to compress it in order to add the note. If anyone cares about the full version, just email me.
[]s
erick2711 at gmail dot com
*/
class nodoMenu{
protected $p = array();
protected $c = array();
public function __construct($t = '', $uri = '', $css = null, $n = 0, $i=0){
$this->p['t'] = $t;$this->p['uri'] = $uri;$this->p['css'] = $css;$this->p['n'] = $n;$this->p['i'] = $i;$this->p['q'] = 0;return $this;
}
public function add($cn, $ct = '', $cl = '', $css = null){
$nc = new nodoMenu($ct, $cl, $css, $this->p['n'] + 1, $this->p['q']);$this->c[$cn] = $nc;$this->p['q'] += 1;return $this->c[$cn];
}
private function isParameter($pn){
return array_key_exists($pn, $this->p);
}
public function __isset($pn){
if ($this->isParameter($pn)){return(!is_null($this->p[$pn]));}
else{return(array_key_exists($pn, $this->c));}
}
public function remove($cn){
if (array_key_exists($cn, $this->c)){$this->p['q'] -= 1;unset($this->c[$cn]);}
}
public function __unset($pn){
if ($this->isParameter($pn)){$this->p[$pn] = null;}
else{$this->remove($pn);}
}
public function __set($pn, $v){
$r = null;
if ($this->isParameter($pn)){$this->p[$pn] = $v;$r = $v;}
else{if (array_key_exists($pn, $this->c)){$this->c[$pn] = $v;$r = $this->c[$pn];}
else{$r = $this->add($pn);}}
return $r;
}
public function __get($pn){
$v = null;
if ($this->isParameter($pn)){$v = $this->p[$pn];}
else{if (array_key_exists($pn, $this->c)){$v = $this->c[$pn];}
else{$v = $this->add($pn);}}
return $v;
}
public function hasChilds(){
return(isset($this->c[0]));
}
public function child($i){
return $this->c[$i];
}
public function strPrint($bm = ''){ //Just to show, replace with something better.
$m = '';$r = '';$n = $this->p['n'];
if ($n > 0){switch($n){case 0:case 1: $qs = 0; break;case 2: $qs = 2; break;case 3: $qs = 6; break;case 4: $qs = 12; break;case 5: $qs = 20; break;case 6: $qs = 30; break;case 7: $qs = 42; break;case 8: $qs = 56; break;}
$tab = str_repeat(' ', $qs);$r .= $tab;
if ($bm <> ''){$m = $bm.'.';}
$im = $this->p['i'] + 1;$m .= $im;$r .= $m.' ';$r .= $this->p['t']."<br>\n";
}
foreach ($this->c as $child){$r .= $child->strPrint($m);}
return $r;
}
public function __toString(){
return $this->strPrint();
}
}
?>
Ant P.
30-Aug-2008 02:01
30-Aug-2008 02:01
There's nothing wrong with calling these functions as normal functions:
If you end up in a situation where you need to know the return value of your __set function, just write <?php $a = $obj->__set($var, $val); ?> instead of <?php $a = $obj->$var = $val; ?>.
strafvollzugsbeamter at gmx dot de
16-Jul-2008 07:57
16-Jul-2008 07:57
The following works on my installation (5.2.6 / Windows):
<?php
class G
{
private $_p = array();
public function __isset($k)
{
return isset($this->_p[$k]);
}
public function __get($k)
{
$v = NULL;
if (array_key_exists($k, $this->_p))
{
$v = $this->_p[$k];
}
else
{
$v = $this->{$k} = $this;
}
return $v;
}
public function __set($k, $v)
{
$this->_p[$k] = $v;
return $this;
}
}
$s = new G();
$s->A->B->C = 'FOO';
$s->X->Y->Z = array ('BAR');
if (isset($s->A->B->C))
{
print($s->A->B->C);
}
else
{
print('A->B->C is NOT set');
}
if (isset($s->X->Y->Z))
{
print_r($s->X->Y->Z);
}
else
{
print('X->Y->Z is NOT set');
}
// prints: FOOArray ( [0] => BAR )
?>
... have fun and ...
Anonymous
30-Apr-2008 08:02
30-Apr-2008 08:02
This is a generic implementation to use getter, setter, issetter and unsetter for your own classes.
<?php
abstract class properties
{
public function __get( $property )
{
if( ! is_callable( array($this,'get_'.(string)$property) ) )
throw new BadPropertyException($this, (string)$property);
return call_user_func( array($this,'get_'.(string)$property) );
}
public function __set( $property, $value )
{
if( ! is_callable( array($this,'set_'.(string)$property) ) )
throw new BadPropertyException($this, (string)$property);
call_user_func( array($this,'set_'.(string)$property), $value );
}
public function __isset( $property )
{
if( ! is_callable( array($this,'isset_'.(string)$property) ) )
throw new BadPropertyException($this, (string)$property);
return call_user_func( array($this,'isset_'.(string)$property) );
}
public function __unset( $property )
{
if( ! is_callable( array($this,'unset_'.(string)$property) ) )
throw new BadPropertyException($this, (string)$property);
call_user_func( array($this,'unset_'.(string)$property) );
}
}
?>
nospam michael AT netkey DOT at nospam
01-Apr-2008 06:10
01-Apr-2008 06:10
you CAN write into ARRAYS by using __set and __get magic functions.
as has been mentioned before $obj->var['key'] = 'test'; does call the __get method of $obj, and there is no way to find out, if the method has been called for setting purposes.
the solution is quite simple: use __get to return the array by reference. then you can write into it:
<?php
class setter{
private $_arr = array();
public function __set($name, $value){
$this->_arr[$name] = $value;
}
public function &__get($name){
if (isset($this->_arr[$name])){
return $this->_arr[$name];
} else return null;
}
}
?>
Matt Creenan
29-Feb-2008 04:34
29-Feb-2008 04:34
PHP4 supports using __call but with a twist that I did not see mentioned anywhere on this page.
In 4, you must make the __call method signature with 3 parameters, the 3rd of which is the return value and must be declared by-reference. Instead of using "return $value;" you would assign the 3rd argument to $value.
Example (both implementations below have the same result when run in the respective PHP versions:
<?php
// Will only work in PHP4
class Foo
{
function __call($method_name, $parameters, &$return_value)
{
$return_value = "Method $method_name was called with " . count($parameters) . " parameters";
}
}
// Will only work in PHP5
class Foo
{
function __call($method_name, $parameters)
{
return "Method $method_name was called with " . count($parameters) . " parameters";
}
}
?>
dave at mozaiq dot org
10-Feb-2008 11:58
10-Feb-2008 11:58
Several users have mentioned ways to allow setting of array properties via magic methods. In particular, PHP calls the __get() method instead of the __set() method when you try to do: $obj->prop['offset'] = $val.
The suggestions that I've read below all work, except that they do not allow you make properties read-only. After a bit of struggling, I have found a solution. Essentially, if the property is supposed to be a read-only array, create an new ArrayObject() out of it, then clone it and return the clone.
<?php
public function __get($var) {
if(isset($this->read_only_props[$var])) {
$ret = null;
if (is_array($this->read_only_props[$var]))
return clone new ArrayObject($this->read_only_props[$var]);
else if (is_object($this->read_only_props[$var]))
return clone $this->read_only_props[$var];
else
return $this->read_only_props[$var];
}
else if (!isset($this->writeable_props[$var]))
$this->writeable_props[$var] = NULL;
return $this->writeable_props[$var];
}
public function __set($var, $val) {
if (isset($this->read_only_props[$var]))
throw new Exception('tried to set a read only property on the event object');
return $this->writeable_props[$var] = $val;
}
?>
Note that __get() does not explicitly return by reference as many examples have suggested. Also, I have not found a way to detect when __get() is being called for setting purposes, thus my code can not throw an exception when necessary in these cases.
timshaw at mail dot NOSPAMusa dot com
29-Jan-2008 05:47
29-Jan-2008 05:47
The __get overload method will be called on a declared public member of an object if that member has been unset.
<?php
class c {
public $p ;
public function __get($name) { return "__get of $name" ; }
}
$c = new c ;
echo $c->p, "\n" ; // declared public member value is empty
$c->p = 5 ;
echo $c->p, "\n" ; // declared public member value is 5
unset($c->p) ;
echo $c->p, "\n" ; // after unset, value is "__get of p"
?>
jj dhoT maturana aht gmail dhot com
25-Jan-2008 12:16
25-Jan-2008 12:16
There isn't some way to overload a method when it's called as a reflection method:
<?php
class TestClass {
function __call($method, $args) {
echo "Method {$method} called with args: " . print_r($args, TRUE);
}
}
$class = new ReflectionClass("TestClass");
$method = $class->getMethod("myMehtod");
//Fatal error: Uncaught exception 'ReflectionException' with message 'Method myMethod' does not exist'
?>
Juan.
Bjrn Wikkeling
21-Jan-2008 10:25
21-Jan-2008 10:25
In response to Anonymous: 09-Jan-2008 10:45.
PHP 5.3 will include the magic method __callStatic to use for static method calls.
see also:
http://bugs.php.net/bug.php?id=26739
v dot umang at gmail dot com
12-Jan-2008 05:20
12-Jan-2008 05:20
If you want to be able to overload a variable from within a class and this is your code:
<?php
class myClass
{
private $data;
public function __set($var, $val)
{
$this->data[$var] = $val;
}
public function __get($var)
{
$this->data[$var] = $val;
}
}
?>
There is a problem if you want to call these variables from within the class, as you you want to access data['data'] then you can't say $this->data as it will return the array $data. Therefore a simple solution is to name the array $_data. So in your __get and __set you will say $this->_data ... rather than $this->data. I.E:
<?php
class myClass
{
private $_data;
public function __set($var, $val)
{
$this->_data[$var] = $val;
}
public function __get($var)
{
$this->_data[$var] = $val;
}
}
?>
Umang
soldair at NOSPAM gmail.com
10-Jan-2008 05:21
10-Jan-2008 05:21
the documentation states a falsehood:
"All overloading methods must be defined as public."
<?php
class test{
#################
#public use methods#
#################
public static function echoData(){
$obj = self::getInstance();
echo $obj->find('data');
return true;
}
######################
#only use a single instance#
######################
private static $instance;
private static function getInstance(){
if(!isset(self::$instance)){
self::$instance = new test;
}
return self::$instance;
}
#################
#private instantiation#
#################
private $data = array('data'=>'i am data');
private function __construct(){}
private function __call($nm,$args){
if(isset($this->data[$args[0]])){
return $this->data[$args[0]];
}
return null;
}
}
test::echoData();
?>
--------------OUTPUT---------------
i am data
-----------------------------------
this test was run using PHP Version 5.2.4
Anonymous
09-Jan-2008 03:45
09-Jan-2008 03:45
it should be noted that __call will trigger only for method calls on an instantiated object, and cannot be used to 'overload' static methods. for example:
<?php
class TestClass {
function __call($method, $args) {
echo "Method {$method} called with args: " . print_r($args, TRUE);
}
}
// this will succeed
$obj = new TestClass();
$obj->method_doesnt_exist();
// this will not
TestClass::method_doesnt_exist();
?>
It would be useful if the PHP devs would include this in a future release, but in the meantime, just be aware of that pitfall.
egingell at sisna dot com
21-Dec-2007 03:54
21-Dec-2007 03:54
The PHP devs aren't going to implement true overloading because: PHP is not strictly typed by any stretch of the imagination (0, "0", null, false, and "" are the same, for example) and unlike Java and C++, you can pass as many values as you want to a function. The extras are ignored unless you fetch them using func_get_arg(int) or func_get_args(), which is often how I "overload" a function/method, and fewer than the declared number of arguments will generate an E_WARNING, which can be suppressed by putting '@' before the function call, but the function will still run as if you had passed null where a value was expected.
<?php
class someClass {
function whatever() {
$args = func_get_args();
// public boolean whatever(boolean arg1) in Java
if (is_bool($args[0])) {
// whatever(true);
return $args[0];
// public int whatever(int arg1, boolean arg2) in Java
} elseif(is_int($args[0]) && is_bool($args[1])) {
// whatever(1, false)
return $args[0];
} else {
// public void whatever() in Java
echo 'Usage: whatever([int], boolean)';
}
}
}
?>
// The Java version:
public class someClass {
public boolean whatever(boolean arg1) {
return arg1;
}
public int whatever(int arg1, boolean arg2) {
return arg1;
}
public void whatever() {
System.out.println("Usage: whatever([int], boolean)");
}
}
matthijs at yourmediafactory dot com
16-Dec-2007 07:09
16-Dec-2007 07:09
While PHP does not support true overloading natively, I have to disagree with those that state this can't be achieved trough __call.
Yes, it's not pretty but it is definately possible to overload a member based on the type of its argument. An example:
<?php
class A {
public function __call ($member, $arguments) {
if(is_object($arguments[0]))
$member = $member . 'Object';
if(is_array($arguments[0]))
$member = $member . 'Array';
$this -> $member($arguments);
}
private function testArray () {
echo "Array.";
}
private function testObject () {
echo "Object.";
}
}
class B {
}
$class = new A;
$class -> test(array()); // echo's 'Array.'
$class -> test(new B); // echo's 'Object.'
?>
Of course, the use of this is questionable (I have never needed it myself, but then again, I only have a very minimalistic C++ & JAVA background). However, using this general principle and optionally building forth on other suggestions a 'form' of overloading is definately possible, provided you have some strict naming conventions in your functions.
It would of course become a LOT easier once PHP'd let you declare the same member several times but with different arguments, since if you combine that with the reflection class 'real' overloading comes into the grasp of a good OO programmer. Lets keep our fingers crossed!
anthony dot parsons at manx dot net
09-Nov-2007 10:57
09-Nov-2007 10:57
You can't use __set to set arrays, but if you really want to, you can emulate it yourself:
<?php
class test {
public $x = array();
public $y = array();
function __set($var, $value)
{
if ( preg_match('/(.*)\[(.*)\]/', $var, $names) ) {
$this->y[$names[1]][$names[2]] = $value;
}
else {
$this->x[$var] = $value;
}
}
}
$z = new test;
$z->variable = 'abc';
$z->{'somearray[key]'} = 'def';
var_dump($z->x);
var_dump($z->y);
?>
php_is_painful at world dot real
19-Oct-2007 02:49
19-Oct-2007 02:49
This is a misuse of the term overloading. This article should call this technique "interpreter hooks".
egingell at sisna dot com
12-Oct-2007 06:26
12-Oct-2007 06:26
@ zachary dot craig at goebelmediagroup dot com
I do something like that, too. My way might be even more clunky.
<?php
function sum() {
$args = func_get_args();
if (!count($args)) {
echo 'You have to supply something to the function.';
} elseif (count($args) == 1) {
return $args[0];
} elseif (count($args) == 2) {
if (is_numeric($args[0]) && is_numeric($args[1])) {
return $args[0] + $args[1];
} else {
return $args[0] . $args[1];
}
}
}
?>
I like the "__call" method, though. You can "declare" multiple functions that don't pollute the namespace. Although, it might be better looking to use this instead of a series of if...elseif... statemenets.
<?php
class myClass {
function __call($fName, $fArgs) {
switch($fName) {
case 'sum':
if (count ($fArgs) === 1) {
return $fArgs[0];
} else {
$retVal = 0;
foreach( $fArgs as $arg ) {
$retVal += $arg;
}
return $retVal;
}
break;
case 'other_method':
...
default:
die ('<div><b>Fetal Error:</b> unknown method ' . $fName . ' in ' . __CLASS__ . '.</div>');
} // end switch
}
}
?>
Side note: if you don't force lower/upper case, you will have case sensitive method names. E.g. $myclass->sum() !== $myclass->Sum().
zachary dot craig at goebelmediagroup dot com
09-Oct-2007 05:13
09-Oct-2007 05:13
@egingell at sisna dot com -
Use of __call makes "overloading" possible also, although somewhat clunky... i.e.
<?php
class overloadExample
{
function __call($fName, $fArgs)
{
if ($fName == 'sum')
{
if (count ($fArgs) === 1)
{
return $fArgs[0];
}
else
{
$retVal = 0;
foreach( $fArgs as $arg )
{
$retVal += $arg;
}
return $retVal;
}
}
}
}
/*
Simple and trivial I realize, but the point is made. Now an object of class overloadExample can take
*/
echo $obj->sum(4); // returns 4
echo $obj->sum(4, 5); // returns 9
?>
bgoldschmidt at rapidsoft dot de
28-Sep-2007 08:23
28-Sep-2007 08:23
"These methods will only be triggered when your object or inherited object doesn't contain the member or method you're trying to access."
is not quite correct:
they get called when the member you trying to access in not visible:
<?php
class test {
public $a;
private $b;
function __set($name, $value) {
echo("__set called to set $name to $value\n");
$this->$name = $value;
}
}
$t = new test;
$t->a = 'a';
$t->b = 'b';
?>
Outputs:
__set called to set b to b
Be aware that set ist not called for public properties
lokrain at gmail dot com
26-Sep-2007 09:05
26-Sep-2007 09:05
Let us look at the following example:
<?php
class objDriver {
private $value;
public function __construct()
{
$value = 1;
}
public function doSomething($parameterList)
{
//We make actions with the value
}
}
class WantStaticCall {
private static $objectList;
private function __construct()
public static function init()
{
self::$objectList = array();
}
public static function register($alias)
{
self::$objectList[$alias] = new objDriver();
}
public static function __call($method, $arguments)
{
$alias = $arguments[0];
array_shift($arguments);
call_user_method($method, self::$objectList[$alias], $arguments);
}
}
// The deal here is to use following code:
WantStaticCall::register('logger');
WantStaticCall::doSomething('logger', $argumentList);
// and we will make objDriver to call his doSomething function with arguments
// $argumentList. This is not common pattern but very usefull in some cases.
// The problem here is that __call() cannot be static, Is there a way to work it around
?>
Typer85 at gmail dot com
18-Sep-2007 03:28
18-Sep-2007 03:28
Just to clarify something the manual states about method overloading.
"All overloading methods must be defined as public."
As of PHP 5.2.2, this should be considered more of a coding convention rather than a requirement. In PHP 5.2.2, declaring a __get or __set function with a visibility other than public, will be silently ignored by the parser and will not trigger a parse error!
What is more, PHP will completely ignore the visibility modifier either of these functions are declared with and will always treat them as if they were public.
I am not sure if this is a bug or not so to be on the safe side,
stick with always declaring them public.
egingell at sisna dot com
15-Sep-2007 12:12
15-Sep-2007 12:12
Small vocabulary note: This is *not* "overloading", this is "overriding".
Overloading: Declaring a function multiple times with a different set of parameters like this:
<?php
function foo($a) {
return $a;
}
function foo($a, $b) {
return $a + $b;
}
echo foo(5); // Prints "5"
echo foo(5, 2); // Prints "7"
?>
Overriding: Replacing the parent class's method(s) with a new method by redeclaring it like this:
<?php
class foo {
function new($args) {
// Do something.
}
}
class bar extends foo {
function new($args) {
// Do something different.
}
}
?>
ac221 at sussex dot ac dot uk
01-Sep-2007 05:07
01-Sep-2007 05:07
Just Noting the interesting behavior of __set __get , when modifying objects contained in overloaded properties.
<?php
class foo {
public $propObj;
public function __construct(){
$propObj = new stdClass();
}
public function __get($prop){
echo("I'm Being Got ! \n");
return $this->propObj->$prop;
}
public function __set($prop,$val){
echo("I'm Being Set ! \n");
$this->propObj->$prop = $val;
}
}
$test = new foo();
$test->barProp = new stdClass(); // I should invoke set
$test->barProp->barSubProp = 'As Should I';
$test->barProp->barSubProp = 'As Should I';
$test->barProp = new stdClass(); // As should i
?>
Outputs:
I'm Being Set !
I'm Being Got !
I'm Being Got !
I'm Being Set !
Whats happening, is PHP is acquiring a reference to the object, triggering __get; Then applying the changes to the object via the reference.
Which is the correct behaviour; objects being special creatures, with an aversion to being cloned...
Unfortunately this will never invoke the __set handler, even though it is modifying a property within 'foo', which is slightly annoying if you wanted to keep track of changes to an objects overloaded properties.
I guess Journaled Objects will have to wait till PHP 6 :)
stephen dot cuppett at webmastersinc dot net
16-Aug-2007 02:10
16-Aug-2007 02:10
Please note, this example will not work on later PHP versions. You must return from __get() by reference using &__get()
php at sleep is the enemy dot co dot uk
23-Jul-2007 02:23
23-Jul-2007 02:23
Just to reinforce and elaborate on what DevilDude at darkmaker dot com said way down there on 22-Sep-2004 07:57.
The recursion detection feature can prove especially perilous when using __set. When PHP comes across a statement that would usually call __set but would lead to recursion, rather than firing off a warning or simply not executing the statement it will act as though there is no __set method defined at all. The default behaviour in this instance is to dynamically add the specified property to the object thus breaking the desired functionality of all further calls to __set or __get for that property.
Example:
<?php
class TestClass{
public $values = array();
public function __get($name){
return $this->values[$name];
}
public function __set($name, $value){
$this->values[$name] = $value;
$this->validate($name);
}
public function validate($name){
/*
__get will be called on the following line
but as soon as we attempt to call __set
again PHP will refuse and simply add a
property called $name to $this
*/
$this->$name = trim($this->$name);
}
}
$tc = new TestClass();
$tc->foo = 'bar';
$tc->values['foo'] = 'boing';
echo '$tc->foo == ' . $tc->foo . '<br>';
echo '$tc ' . (property_exists($tc, 'foo') ? 'now has' : 'still does not have') . ' a property called "foo"<br>';
/*
OUPUTS:
$tc->foo == bar
$tc now has a property called "foo"
*/
?>
Adeel Khan
10-Jul-2007 08:18
10-Jul-2007 08:18
Observe:
<?php
class Foo {
function __call($m, $a) {
die($m);
}
}
$foo = new Foo;
print $foo->{'wow!'}();
// outputs 'wow!'
?>
This method allows you to call functions with invalid characters.
alexandre at nospam dot gaigalas dot net
08-Jul-2007 05:59
08-Jul-2007 05:59
PHP 5.2.1
Its possible to call magic methods with invalid names using variable method/property names:
<?php
class foo
{
function __get($n)
{
print_r($n);
}
function __call($m, $a)
{
print_r($m);
}
}
$test = new foo;
$varname = 'invalid,variable+name';
$test->$varname;
$test->$varname();
?>
I just don't know if it is a bug or a feature :)
BenBE at omorphia dot de
05-May-2007 05:48
05-May-2007 05:48
While playing a bit with the __call magic method I found you can not emulate implementing methods of an interface as you might think:
<?php
class Iteratable implements Iterator {
public function __call($funcname) {
if(in_array($funcname, array('current', 'next', /*...*/)) {
//Redirect the call or perform the actual action
}
}
}
?>
Using this code you'll get a "class Iteratable contains abstract methods ..." fatal error message. You'll ALWAYS have to implement those routines by hand.
j dot stubbs at linkthink dot co dot jp
27-Feb-2007 05:53
27-Feb-2007 05:53
In reply to james at thunder-removeme-monkey dot net,
Unfortunately it seems that there is no way to have completely transparent array properties with 5.2.x. The code you supplied works until working with built-in functions that perform type-checks:
<?php
// Using the same View class
$view = new View();
$view->bar = array();
$view->bar[] = "value";
if (is_array($view->bar))
print "is array!\n"; // Not printed
// Warning: in_array(): Wrong datatype for second argument in ...
if (in_array("value", $view->bar))
print "found!\n"; // Not printed
// Successful
if (in_array("value", (array)$view->bar))
print "found!\n";
?>
It also seems that 5.1.x is no longer maintained as it's not listed on the downloads page.. Quite frustrating. :/
mafu at spammenot-mdev dot dk
24-Feb-2007 10:24
24-Feb-2007 10:24
As a reply to james at thunder-removeme-monkey dot net, I found that there is a much simpler way to restore the behavior of __get() to 5.1.x state; just force __get() to return by reference, like this:
<?php
class View {
/* Somewhere to store our overloaded properties */
private $v = array();
/* Store a new property */
function __set($varName, $varValue) {
$this->v[$varName] = $varValue;
}
/* Retrieve a property */
function & __get($varName) {
if(!isset($this->v[$varName])) {
$this->v[$varName] = NULL;
}
return $this->v[$varName];
}
}
?>
The only problem is that the code generates a notice if null is returned in __get(), because null cannot be returned by reference. If somebody finds a solution, feel free to email me. :)
Cheers
james at thunder-removeme-monkey dot net
31-Jan-2007 09:07
31-Jan-2007 09:07
Following up on the comment by "jstubbs at work-at dot co dot jp" and after reading "http://weierophinney.net/matthew/archives/ 131-Overloading-arrays-in-PHP-5.2.0.html", the following methods handle property overloading pretty neatly and return variables in read/write mode.
<?php
class View {
/* Somewhere to store our overloaded properties */
private $v = array();
/* Store a new property */
function __set($varName, $varValue) {
$this->v[$varName] = $varValue;
}
/* Retrieve a property */
function __get($varName) {
if(!isset($this->v[$varName])) {
$this->v[$varName] = NULL;
}
return is_array($this->v[$varName]) ? new ArrayObject($this->v[$varName]) : $this->v[$varName];
}
}
?>
This is an amalgm of previous solutions with the key difference being the use of ArrayObject in the return value. This is more flexible than having to extend the whole class from ArrayObject.
Using the above class, we can do ...
<?php
$obj = new SomeOtherObject();
$view = new View();
$view->list = array();
$view->list[] = "hello";
$view->list[] = "goat";
$view->list[] = $group;
$view->list[] = array("a", "b", "c");
$view->list[3][] = "D";
$view->list[2]->aprop = "howdy";
/*
$view->list now contains:
[0] => "hello"
[1] => "goat"
[2] => SomeOtherObject { aprop => "howdy" }
[3] => array("a", "b", "c", "D")
and
$obj === $view->list[2] // equates to TRUE
*/
?>
mhherrera31 at hotmail dot com
25-Nov-2006 06:11
25-Nov-2006 06:11
example for read only properties in class object. Lets you manage read only properties with var names like $ro_var.
The property must be PRIVATE, otherwise the overload method __get doesn't be called.
<?php
class Session {
private $ro_usrName;
function __construct (){
$this->ro_usrName = "Marcos";
}
function __set($set, $val){
if(property_exists($this,"ro_".$set))
echo "The property '$set' is read only";
else
if(property_exists($this,$set))
$this->{$set}=$val;
else
echo "Property '$set' doesn't exist";
}
function __get{$get}{
if(property_exists($this,"ro_".$get))
return $this->{"ro_".$get};
else
if(property_exists($this,$get))
return $this->{$get};
else
echo "Property '$get' doesn't exist";
}
}
?>
MagicalTux at ooKoo dot org
06-Sep-2006 09:35
06-Sep-2006 09:35
Since many here probably wanted to do «real» overloading without having to think too much, here's a generic __call() function for those cases.
Little example :
<?php
class OverloadedClass {
public function __call($f, $p) {
if (method_exists($this, $f.sizeof($p))) return call_user_func_array(array($this, $f.sizeof($p)), $p);
// function does not exists~
throw new Exception('Tried to call unknown method '.get_class($this).'::'.$f);
}
function Param2($a, $b) {
echo "Param2($a,$b)\n";
}
function Param3($a, $b, $c) {
echo "Param3($a,$b,$c)\n";
}
}
$o = new OverloadedClass();
$o->Param(4,5);
$o->Param(4,5,6);
$o->ParamX(4,5,6,7);
?>
Will output :
Param2(4,5)
Param3(4,5,6)
Fatal error: Uncaught exception 'Exception' with message 'Tried to call unknown method OverloadedClass::ParamX' in overload.php:7
Stack trace:
#0 [internal function]: OverloadedClass->__call('ParamX', Array)
#1 overload.php(22): OverloadedClass->ParamX(4, 5, 6, 7)
#2 {main}
thrown in overload.php on line 7
jstubbs at work-at dot co dot jp
02-Sep-2006 04:12
02-Sep-2006 04:12
<?php $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:
<?php
$tmp_array = &$myclass->foo;
$tmp_array['bar'] = 'baz';
unset($tmp_array);
?>
Therefore, the above won't do anything if your __get implementation resembles this:
<?php
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:
<?php
function __get($name) {
if (!array_key_exists($name, $this->values))
$this->values[$name] = null;
return $this->values[$name];
}
?>
mnaul at nonsences dot angelo dot edu
11-Jul-2006 07:58
11-Jul-2006 07:58
This is just my contribution. It based off of many diffrent suggestions I've see thought the manual postings.
It should fit into any class and create default get and set methods for all you member variables. Hopfuly its usefull.
<?php
public function __call($name,$params)
{
if( preg_match('/(set|get)(_)?/',$name) )
{
if(substr($name,0,3)=="set")
{
$name = preg_replace('/set(_)?/','',$name);
if(property_exists(__class__,$name))
{
$this->{$name}=array_pop($params);
return true;
}
else
{
//call to class error handler
return false;
}
return true;
}
elseif(substr($name,0,3)=="get")
{
$name = preg_replace('/get(_)?/','',$name);
if(property_exists(__class__,$name) )
{
return $this->{$name};
}
else
{
//call to class error handler
return false;
}
}
else
{
//call to class error handler
return false;
}
}
else
{
die("method $name dose not exist\n");
}
return false;
}
me at brenthagany dot com
12-Apr-2006 05:52
12-Apr-2006 05:52
Regarding the post by TJ earlier, about the problems extending DOMElement. Yes, it is true that you can't set extDOMElement::ownerDocument directly; however, you could append the extDOMElement to a DOMDocument in __construct(), which indirectly sets ownerDocument. It should work something like so:
<?php
class extDOMElement extends DOMElement {
public function __construct(DOMDocument $doc) {
$doc->appendChild($this); //extDOMElement::ownerDocument is now equal to the object that $doc points to
}
}
?>
Now, I admit I've never actually needed to do this, but I see no reason why it shouldn't work.
Sleepless
24-Feb-2006 07:22
24-Feb-2006 07:22
Yet another way of providing support for read-only properties. Any property that has
"pri_" as a prefix will NOT be returned, period, any other property will be returned
and if it was declared to be "protected" or "private" it will be read-only. (scope dependent of course)
<?php
function __get($var){
if (property_exists($this,$var) && (strpos($var,"pri_") !== 0) )
return $this->{$var};
else
//Do something
}
?>
Eric Lafkoff
22-Feb-2006 06:56
22-Feb-2006 06:56
If you're wondering how to create read-only properties for your class, the __get() and __set() functions are what you're looking for. You just have to create the framework and code to implement this functionality.
Here's a quick example I've written. This code doesn't take advantage of the "type" attribute in the properties array, but is there for ideas.
<?php
class Test {
private $p_arrPublicProperties = array(
"id" => array("value" => 4,
"type" => "int",
"readonly" => true),
"datetime" => array("value" => "Tue 02/21/2006 20:49:23",
"type" => "string",
"readonly" => true),
"data" => array("value" => "foo",
"type" => "string",
"readonly" => false)
);
private function __get($strProperty) {
//Get a property:
if (isset($this->p_arrPublicProperties[$strProperty])) {
return $this->p_arrPublicProperties[$strProperty]["value"];
} else {
throw new Exception("Property not defined");
return false;
}
}
private function __set($strProperty, $varValue) {
//Set a property to a value:
if (isset($this->p_arrPublicProperties[$strProperty])) {
//Check if property is read-only:
if ($this->p_arrPublicProperties[$strProperty]["readonly"]) {
throw new Exception("Property is read-only");
return false;
} else {
$this->p_arrPublicProperties[$strProperty]["value"] = $varValue;
return true;
}
} else {
throw new Exception("Property not defined");
return false;
}
}
private function __isset($strProperty) {
//Determine if property is set:
return isset($this->p_arrPublicProperties[$strProperty]);
}
private function __unset($strProperty) {
//Unset (remove) a property:
unset($this->p_arrPublicProperties[$strProperty]);
}
}
$objTest = new Test();
print $objTest->data . "\n";
$objTest->data = "bar"; //Works.
print $objTest->data;
$objTest->id = 5; //Error: Property is read-only.
?>
derek-php at seysol dot com
10-Feb-2006 08:08
10-Feb-2006 08:08
Please note that PHP5 currently doesn't support __call return-by-reference (see PHP Bug #30959).
Example Code:
<?php
class test {
public function &__call($method, $params) {
// Return a reference to var2
return $GLOBALS['var2'];
}
public function &actual() {
// Return a reference to var1
return $GLOBALS['var1'];
}
}
$obj = new test;
$GLOBALS['var1'] = 0;
$GLOBALS['var2'] = 0;
$ref1 =& $obj->actual();
$GLOBALS['var1']++;
echo "Actual function returns: $ref1 which should be equal to " . $GLOBALS['var1'] . "<br/>\n";
$ref2 =& $obj->overloaded();
$GLOBALS['var2']++;
echo "Overloaded function returns: $ref2 which should be equal to " . $GLOBALS['var2'] . "<br/>\n";
?>
PHP at jyopp dotKomm
22-Dec-2005 07:01
22-Dec-2005 07:01
Here's a useful class for logging function calls. It stores a sequence of calls and arguments which can then be applied to objects later. This can be used to script common sequences of operations, or to make "pluggable" operation sequences in header files that can be replayed on objects later.
If it is instantiated with an object to shadow, it behaves as a mediator and executes the calls on this object as they come in, passing back the values from the execution.
This is a very general implementation; it should be changed if error codes or exceptions need to be handled during the Replay process.
<?php
class MethodCallLog {
private $callLog = array();
private $object;
public function __construct($object = null) {
$this->object = $object;
}
public function __call($m, $a) {
$this->callLog[] = array($m, $a);
if ($this->object) return call_user_func_array(array(&$this->object,$m),$a);
return true;
}
public function Replay(&$object) {
foreach ($this->callLog as $c) {
call_user_func_array(array(&$object,$c[0]), $c[1]);
}
}
public function GetEntries() {
$rVal = array();
foreach ($this->callLog as $c) {
$rVal[] = "$c[0](".implode(', ', $c[1]).");";
}
return $rVal;
}
public function Clear() {
$this->callLog = array();
}
}
$log = new MethodCallLog();
$log->Method1();
$log->Method2("Value");
$log->Method1($a, $b, $c);
// Execute these method calls on a set of objects...
foreach ($array as $o) $log->Replay($o);
?>
trash80 at gmail dot com
04-Dec-2005 04:59
04-Dec-2005 04:59
Problem: $a->b->c(); when b is not instantiated.
Answer: __get()
<?php
class a
{
function __get($v)
{
$this->$v = new $v;
return $this->$v;
}
}
class b
{
function say($word){
echo $word;
}
}
$a = new a();
$a->b->say('hello world');
// echos 'hello world'
?>
TJ <php at tjworld dot net>
04-Nov-2005 06:11
04-Nov-2005 06:11
Using the getter/setter methods to provide read-only access to object properties breaks the conventional understanding of inheritence.
A super class using __set() to make a property read-only cannot be properly inherited because the visible (read-only) property - with conventional public or protected visibility - cannot be set in the sub-class.
The sub-class cannot overload the super class's __set() method either, and therefore the inheritence is severely compromised.
I discovered this issue while extending DOMDocument and particularly DOMElement.
When extDOMDocument->createElement() creates a new extDOMElement, extDOMElement->__construct() can't set the extDOMElement->ownerDocument property because it's read-only.
DOMElements are totally read-only if they do not have an ownerDocument, and there's no way to set it in this scenario, which makes inheritence pretty pointless.
seufert at gmail dot com
02-Nov-2005 12:25
02-Nov-2005 12:25
This allows you to seeminly dynamically overload objects using plugins.
<?php
class standardModule{}
class standardPlugModule extends standardModule
{
static $plugptrs;
public $var;
static function plugAdd($name, $mode, $ptr)
{
standardPlugModule::$plugptrs[$name] = $ptr;
}
function __call($fname, $fargs)
{ print "You called __call($fname)\n";
$func = standardPlugModule::$plugptrs[$fname];
$r = call_user_func_array($func, array_merge(array($this),$fargs));
print "Done: __call($fname)\n";
return $r;
}
function dumpplugptrs() {var_dump(standardPlugModule::$plugptrs); }
}
class a extends standardPlugModule
{ function text() { return "Text"; } }
//Class P contained within a seperate file thats included
class p
{ static function plugin1($mthis, $r)
{ print "You called p::plugin1\n";
print_r($mthis);
print_r($r);
}
} a::plugAdd('callme', 0, array('p','plugin1'));
//Class P contained within a seperate file thats included
class p2
{ static function plugin2($mthis, $r)
{ print "You called p2::plugin2\n";
$mthis->callme($r);
}
} a::plugAdd('callme2', 0, array('p2','plugin2'));
$t = new a();
$testr = array(1,4,9,16);
print $t->text()."\n";
$t->callme2($testr);
//$t->dumpplugptrs();
?>
Will result in:
----------
Text
You called __call(callme2)
You called p2::plugin2
You called __call(callme)
You called p::plugin1
a Object
(
[var] =>
)
Array
(
[0] => 1
[1] => 4
[2] => 9
[3] => 16
)
Done: __call(callme)
Done: __call(callme2)
----------
This also clears up a fact that you can nest __call() functions, you could use this to get around the limits to __get() not being able to be called recursively.
26-Aug-2005 02:32
To those who wish for "real" overloading: there's not really any advantage to using __call() for this -- it's easy enough with func_get_args(). For example:
<?php
class Test
{
public function Blah()
{
$args = func_get_args();
switch (count($args))
{
case 1: /* do something */ break;
case 2: /* do something */ break;
}
}
}
?>
NOTE: getter cannot call getter
04-Aug-2005 07:37
04-Aug-2005 07:37
By Design (http://bugs.php.net/bug.php?id=33998) you cannot call a getter from a getter or any function triggered by a getter:
<?php
class test
{
protected $_a = 6;
function __get($key) {
if($key == 'stuff') {
return $this->stuff();
} else if($key == 'a') {
return $this->_a;
}
}
function stuff()
{
return array('random' => 'key', 'using_getter' => 10 * $this->a);
}
}
$test = new test();
print 'this should be 60: '.$test->stuff['using_getter'].'<br/>'; // prints "this should be 60: 0"
// [[ Undefined property: test::$a ]] on /var/www/html/test.php logged.
print 'this should be 6: '.$test->a.'<br/>'; // prints "this should be 6: 6"
?>
06-May-2005 10:50
Please note that PHP5's overloading behaviour is not compatible at all with PHP4's overloading behaviour.
Marius
02-May-2005 09:15
02-May-2005 09:15
for anyone who's thinking about traversing some variable tree
by using __get() and __set(). i tried to do this and found one
problem: you can handle couple of __get() in a row by returning
an object which can handle consequential __get(), but you can't
handle __get() and __set() that way.
i.e. if you want to:
<?php
print($obj->val1->val2->val3); // three __get() calls
?> - this will work,
but if you want to:
<?php
$obj->val1->val2 = $val; // one __get() and one __set() call
?> - this will fail with message:
"Fatal error: Cannot access undefined property for object with
overloaded property access"
however if you don't mix __get() and __set() in one expression,
it will work:
<?php
$obj->val1 = $val; // only one __set() call
$val2 = $obj->val1->val2; // two __get() calls
$val2->val3 = $val; // one __set() call
?>
as you can see you can split __get() and __set() parts of
expression into two expressions to make it work.
by the way, this seems like a bug to me, will have to report it.
ryo at shadowlair dot info
22-Mar-2005 06:22
22-Mar-2005 06:22
Keep in mind that when your class has a __call() function, it will be used when PHP calls some other magic functions. This can lead to unexpected errors:
<?php
class TestClass {
public $someVar;
public function __call($name, $args) {
// handle the overloaded functions we know...
// [...]
// raise an error if the function is unknown, just like PHP would
trigger_error(sprintf('Call to undefined function: %s::%s().', get_class($this), $name), E_USER_ERROR);
}
}
$obj = new TestClass();
$obj->someVar = 'some value';
echo $obj; //Fatal error: Call to undefined function: TestClass::__tostring().
$serializedObj = serialize($obj); // Fatal error: Call to undefined function: TestClass::__sleep().
$unserializedObj = unserialize($someSerializedTestClassObject); // Fatal error: Call to undefined function: TestClass::__wakeup().
?>
thisisroot at gmail dot com
18-Feb-2005 03:27
18-Feb-2005 03:27
You can't mix offsetSet() of the ArrayAccess interface (http://www.php.net/~helly/php/ext/spl/interfaceArrayAccess.html) and __get() in the same line.
Below, "FileManagerPrefs" is an object of class UserData which implements ArrayAccess. There's a protected array of UserData objects in the User class, which are returned from __get().
<?php
// This produces an error...
Application::getInstance()->user->FileManagerPrefs[ 'base'] = 'uploads/jack';
?>
Creates this error:
Fatal error: Cannot access undefined property for object with overloaded property access in __FILE__ on line __LINE__
However, __get() and offsetGet() play deceptively well together.
<?php
// This works fine!
echo Application::getInstance()->user->FileManager['base'];
?>
I guess it's a dereferencing issue with __get(). In my case, it makes more sense to have a middle step (user->data['FileManager']['base']), but I wanted to tip off the community before I move on.
mileskeaton at gmail dot com
23-Dec-2004 08:23
23-Dec-2004 08:23
<?php
## THE PROBLEM: Class with lots of attributes.
## You want to use $o->getVarName() or $o->get_varname() style getters
## Some attributes have custom get functions, but the rest don't
## THE SOLUTION: __call
class Person
{
## this top stuff is just an example. could be anything.
private $name;
private $age;
private $weight;
function __construct($name, $age, $weight)
{
$this->name = $name;
$this->age = $age;
$this->weight = $weight;
}
## PORTABLE: use this __call function in any class
function __call($val, $x)
{
# see if they're calling a getter method - and try to guess the variable requested
if(substr($val, 0, 4) == 'get_')
{
$varname = substr($val, 4);
}
elseif(substr($val, 0, 3) == 'get')
{
$varname = substr($val, 3);
}
else
{
die("method $val does not exist\n");
}
# now see if that variable exists:
foreach($this as $class_var=>$class_var_value)
{
if(strtolower($class_var) == strtolower($varname))
{
return $class_var_value;
}
}
return false;
}
# IMPORTANT: you can keep some things private - or treat
# some vars differently by giving them their own getter method
# See how this function lies about Person's weight.
function getWeight()
{
return intval($this->weight * .8);
}
}
$a = new Person('Miles', 35, 200);
# these all work (case-insensitive):
print $a->get_name() . "\n";
print $a->getName() . "\n";
print $a->get_Name() . "\n";
print $a->getname() . "\n";
print $a->get_age() . "\n";
print $a->getAge() . "\n";
print $a->getage() . "\n";
print $a->get_Age() . "\n";
# defined functions still override the __call
print $a->getWeight() . "\n";
# trying to get something that doesn't exist returns false
print $a->getNothing();
# this still gets error:
print $a->hotdog();
?>
richard dot quadling at bandvulc dot co dot uk
26-Nov-2004 01:54
26-Nov-2004 01:54
<?php
abstract class BubbleMethod
{
public $objOwner;
function __call($sMethod, $aParams)
{
// Has the Owner been assigned?
if (isset($this->objOwner))
{
return call_user_func_array(array($this->objOwner, $sMethod), $aParams);
}
else
{
echo 'Owner for ' . get_class($this) . ' not assigned.';
}
}
}
class A_WebPageContainer
{
private $sName;
public function __construct($sName)
{
$this->sName = $sName;
}
public function GetWebPageContainerName()
{
return $this->sName;
}
}
class A_WebFrame extends BubbleMethod
{
private $sName;
public function __construct($sName)
{
$this->sName = $sName;
}
public function GetWebFrameName()
{
return $this->sName;
}
}
class A_WebDocument extends BubbleMethod
{
private $sName;
public function __construct($sName)
{
$this->sName = $sName;
}
public function GetWebDocumentName()
{
return $this->sName;
}
}
class A_WebForm extends BubbleMethod
{
private $sName;
public function __construct($sName)
{
$this->sName = $sName;
}
public function GetWebFormName()
{
return $this->sName;
}
}
class A_WebFormElement extends BubbleMethod
{
private $sName;
public function __construct($sName)
{
$this->sName = $sName;
}
public function GetWebFormElementName()
{
return $this->sName;
}
}
$objWPC = new A_WebPageContainer('The outer web page container.');
$objWF1 = new A_WebFrame('Frame 1');
$objWF1->objOwner = $objWPC;
$objWF2 = new A_WebFrame('Frame 2');
$objWF2->objOwner = $objWPC;
$objWD1 = new A_WebDocument('Doc 1');
$objWD1->objOwner = $objWF1;
$objWD2 = new A_WebDocument('Doc 2');
$objWD2->objOwner = $objWF2;
$objWFrm1 = new A_WebForm('Form 1');
$objWFrm1->objOwner = $objWD1;
$objWFrm2 = new A_WebForm('Form 2');
$objWFrm2->objOwner = $objWD2;
$objWE1 = new A_WebFormElement('Element 1');
$objWE1->objOwner = $objWFrm1;
$objWE2 = new A_WebFormElement('Element 2');
$objWE2->objOwner = $objWFrm1;
$objWE3 = new A_WebFormElement('Element 3');
$objWE3->objOwner = $objWFrm2;
$objWE4 = new A_WebFormElement('Element 4');
$objWE4->objOwner = $objWFrm2;
echo "The name of the form that '" . $objWE1->GetWebFormElementName() . "' is in is '" . $objWE1->GetWebFormName() . "'<br />";
echo "The name of the document that '" . $objWE2->GetWebFormElementName() . "' is in is '" . $objWE2->GetWebDocumentName(). "'<br />";
echo "The name of the frame that '" . $objWE3->GetWebFormElementName() . "' is in is '" . $objWE3->GetWebFrameName(). "'<br />";
echo "The name of the page container that '" . $objWE4->GetWebFormElementName() . "' is in is '" .$objWE4->GetWebPageContainerName(). "'<br />";
?>
Results in.
The name of the form that 'Element 1' is in is 'Form 1'
The name of the document that 'Element 2' is in is 'Doc 1'
The name of the frame that 'Element 3' is in is 'Frame 2'
The name of the page container that 'Element 4' is in is 'The outer web page container.'
By using the abstract BubbleMethod class as the starting point for further classes that are contained inside others (i.e. elements on a form are contained in forms, which are contained in documents which are contained in frames which are contained in a super wonder global container), you can find properties of owner without knowing their direct name.
Some work needs to be done on what to do if no method exists though.
xorith at gmail dot com
06-Oct-2004 02:40
06-Oct-2004 02:40
A few things I've found about __get()...
First off, if you use $obj->getOne->getAnother, both intended to be resolved by __get, the __get() function only sees the first one at first. You can't access the second one. You can, however, return the pointer to an object that can handle the second one. In short, you can have the same class handle both by returning a new object with the data changed however you see fit.
Secondly, when using arrays like: $obj->getArray["one"], only the array name is passed on to __get. However, when you return the array, PHP treats it just as it should. THat is, you'd have to make an array with the index of "one" in __get in order to see any results. You can also have other indexes in there as well.
Also, for those of you like me, I've already tried to use func_get_args to see if you can get more than just that one.
If you're like me and were hoping you could pass some sort of argument onto __get in order to help gather the correct data, you're out of look. I do recommend using __call though. You could easily rig __call up to react to certain things, like: $account->properties( "type" );, which is my example. I'm using DOM for data storage (for now), and I'm trying to make an interface that'll let me easily switch to something else - MySQL, flat file, anything. This would work great though!
Hope I've been helpful and I hope I didn't restate something already stated.
anthony at ectrolinux dot com
26-Sep-2004 01:40
26-Sep-2004 01:40
For anyone who is interested in overloading a class method based on the number of arguments, here is a simplified example of how it can be accomplished:
<?php
function Error($message) { trigger_error($message, E_USER_ERROR); exit(1); }
class Framework
{
// Pseudo function overloading
public function __call($func_name, $argv)
{
$argc = sizeof($argv);
switch ($func_name) {
case 'is_available':
$func_name = ($argc == 2) ? 'is_available_single' : 'is_available_multi';
break;
default: // If no applicable function was found, generate the default PHP error message.
Error('Call to undefined function Framework::'. $func_name .'().');
}
return call_user_func_array(array(&$this, $func_name), $argv);
}
// protected array is_available_multi($mod_name, $mod_addon_0 [, $mod_addon_1 [, ...]])
protected function is_available_multi()
{
if (($argc = func_num_args()) < 2) {
Error('A minimum of two arguments are required for Framework::is_available().');
}
$available_addons = array();
// --snip--
return $available_addons;
}
protected function is_available_single($mod_name, $mod_addon)
{
// --snip--
return true;
}
}
$fw = new Framework;
$test_one = $fw->is_available('A_Module_Name', 'An_Addon');
var_dump($test_one);
// Test one produces a boolean value, supposedly representing whether 'An_Addon' is available and can be used.
$test_two = $fw->is_available('A_Module_Name', 'Addon_0', 'Addon_1', 'Addon_2');
var_dump($test_two);
// Test two produces an array, supposedly listing any of the three 'Addon_N' modules that are available and can be used.
// Here are the actual results of the above:
// bool(true)
// array(0) {
// }
?>
---
By adding additional case statements to Framework::__call(), methods can easily be overloaded as needed. It's also possible to add any other overloading criteria you require inside the switch statement, allowing for more intricate overloading functionality.
DevilDude at darkmaker dot com
23-Sep-2004 02:57
23-Sep-2004 02:57
Php 5 has a simple recursion system that stops you from using overloading within an overloading function, this means you cannot get an overloaded variable within the __get method, or within any functions/methods called by the _get method, you can however call __get manualy within itself to do the same thing.