method_exists

(PHP 4, PHP 5)

method_existsPrüft on eine Methode innerhalb eines Objekts existiert

Beschreibung

bool method_exists ( mixed $object , string $method_name )

Prüft ob eine Methode mit Namen method_name im Objekt objekt definiert ist.

Parameter-Liste

object

Eine Objektinstanz oder ein Klassenname

method_name

Der gewünschte Methodenname

Rückgabewerte

Liefert TRUE wenn die Methode method_name im Objekt objekt definiert ist, sonst FALSE.

Beispiele

Beispiel #1 method_exists() Beispiel

<?php
$directory 
= new Directory('.');
var_dump(method_exists($directory,'read'));
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

bool(true)

Beispiel #2 Statisches method_exists() Beispiel

<?php
var_dump
(method_exists('Directory','read'));
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

bool(true)

Siehe auch

  • function_exists() - Falls die angegebene Funktion definiert ist, wird TRUE zurück gegeben
  • is_callable() - Prüft ob der Inhalt einer Variable als Funktion aufgerufen werden kann

add a note add a note

User Contributed Notes 17 notes

up
16
phoenix at todofixthis dot com
3 years ago
As noted [elsewhere] method_exists() does not care about the existence of __call(), whereas is_callable() does:

<?php
class Test {
  public function
explicit(  ) {
     
// ...
 
}
  
  public function
__call( $meth, $args ) {
     
// ...
 
}
}

$Tester = new Test();

var_export(method_exists($Tester, 'anything')); // false
var_export(is_callable(array($Tester, 'anything'))); // true
?>
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3
konzertheld at thedomainistheusersname dot de
1 year ago
Note that prepending the namespace (if any) is required even if the calling class is in the same namespace:

<?php
namespace test;
class
foo {
public function
lookup() {
 
// will return false
 
return method_exists('bar', 'nonsense_method');
}
}

class
bar {
public function
nonsense_method() {
 
// will return true
 
return method_exists('test\foo', 'lookup');
}
}
?>
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2
mail at bartrail dot de
3 years ago
Using method_exists inside an object's __call() method can be very usefull if you want to avoid to get a fatal error because of a limit in function nesting or if you are calling methods that dont exist but need to continue in your application:

<?php
class Something
{

   
/**
     * Call a method dynamically
     *
     * @param string $method
     * @param array $args
     * @return mixed
     */
   
public function __call($method, $args)
    {
        if(
method_exists($this, $method)) {
          return
call_user_func_array(array($this, $method), $args);
        }else{
          throw new
Exception(sprintf('The required method "%s" does not exist for %s', $method, get_class($this)));
        }
    }

}
?>
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2
admin ( at ) djokodonev dot com
5 years ago
Hi,

Here is a useful function that  you can use to check classes methods access e.g whether it is public, private or static or both..

here it goes:

<?php
// Example class
class myClass {

    private
$private1;
   
    static
$static1;
   
    public
$public1;
       
   
    public function
publ() {
   
    }
   
    private function
priv() {
   
    }
   
    private static function
privstatic() {

    }
   
    public static function
publstatic() {
   
    }
   
    static function
mytest() {
   
    }
}

// The function uses the reflection class that is built into PHP!!!
// The purpose is to determine the type of a certain method that exi
function is_class_method($type="public", $method, $class) {
  
// $type = mb_strtolower($type);
   
$refl = new ReflectionMethod($class, $method);
    switch(
$type) {
        case
"static":
        return
$refl->isStatic();
        break;
        case
"public":
        return
$refl->isPublic();
        break;
        case
"private":
        return
$refl->isPrivate();
        break;
    }
}
var_dump(is_class_method("static", "privstatic", "myClass")); // true - the method is  private and also static..
var_dump(is_class_method("private", "privstatic", "myClass")); // true - the method is  private and also static..
var_dump(is_class_method("private", "publstatic", "myClass")); // False the methos is public and also static not private
// you get the idea.. I hope this helps someone..
?>
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2
daniel at softel dot jp
8 years ago
Note that in PHP5, method_exists() will sucessfully find *private* methods. This has some OO/data-hiding ramifications.
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3
Niels
3 years ago
Just to mention it: both method_exists() and is_callable() return true for inherited methods:

<?php
class ParentClass {

   function
doParent() { }
}

class
ChildClass extends ParentClass { }

$p = new ParentClass();
$c = new ChildClass();

// all return true
var_dump(method_exists($p, 'doParent'));
var_dump(method_exists($c, 'doParent'));

var_dump(is_callable(array($p, 'doParent')));
var_dump(is_callable(array($c, 'doParent')));
?>
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2
florin from syneto net
5 years ago
This function is case-insensitive (as is PHP) and here is the proof:
<?php
class A {
    public function
FUNC() { echo '*****'; }
}

$a = new A();
$a->func(); // *****
var_dump(method_exists($a, 'func')); // bool(true)
?>
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2
jp at function dot fi
8 years ago
As mentioned before, is_callable and method_exists report all methods callable even if they are private/protected and thus actually not callable. So instead of those functions you may use following work-around which reports methods as supposed to.

<?php
class Foo1 {
  public function
bar() {
    echo
"I'm private Foo1::bar()";
  }
}

class
Foo2 {
  private function
bar() {
    echo
"I'm public Foo2::bar()";
  }
}

$f1=new Foo1;
$f2=new Foo2;

if(
is_callable(array($f1,"bar"))) {
    echo
"Foo1::bar() is callable";
} else {
    echo
"Foo1::bar() isn't callable";
}
if(
is_callable(array($f2,"bar"))) {
    echo
"Foo2::bar() is callable";
} else {
    echo
"Foo2::bar() isn't callable";
}
if(
in_array("bar",get_class_methods($f1))) {
    echo
"Foo1::bar() is callable";
} else {
    echo
"Foo1::bar() isn't callable";
}
if(
in_array("bar",get_class_methods($f2))) {
    echo
"Foo2::bar() is callable";
} else {
    echo
"Foo2::bar() isn't callable";
}

?>

output
Foo1::bar() is callable (correct)
Foo2::bar() is callable (incorrect)
Foo1::bar() is callable (correct)
Foo2::bar() isn't callable (correct)

?>
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2
uramihsayibok, gmail, com
4 years ago
It wasn't spelled out but could be inferred: method_exists() also works on interfaces.

<?php

var_dump
(method_exists("Iterator", "current"));
// bool(true)

?>
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0
charleston olaes at gmail no spaces
1 month ago
I was wondering if caching the the methods in an array would have a faster lookup. So I ran a very simple benchmark using xdebug_time_index() with 10000 iterations on each statement.

using PHP 5.3.13 btw

<?php
// using an actual instance of an object shows 0.10398316383362 secs
method_exist($object, $method);
?>

<?php
// using a string shows 0.12779307365417 secs
method_exist('ClassName', $method);
?>

<?php
$array
= array(/*method names with numeric index*/);
// shows 0.10288906097412 secs
in_array($method, $array);
?>

<?php
$assoc
= array( /*method name as key and value*/ );
// shows 0.017536878585815 secs
isset( $assoc[$method] );
?>

From the looks of the results, there is very little difference in method_exist and in_array. Isset seems to the fastest and using a string as the first parameter is the slowest.

Please note that the test was done on multiple methods, not just one, the code presented above is to show the results, not the actual test code that ran. Also, this was tested just out of curiosity and I didn't set up a specific environment or used any profiling tools, and it was not meant to be an official benchmark in anyway.
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1
benjamin_ansbach at web dot de
11 years ago
if you want to check for a method "inside" of a class use:

method_exists($this, 'function_name')

i was a bit confused 'cause i thought i'm only able to check for a method when i got an object like $object_name = new class_name() with:

method_exists($object_name, 'method_name')

small example for those who didn't understood what i mean ( maybe caused by bad english :) ):

<?php

class a {

    function
a() {
       
        if(
method_exists($this, 'test'))
            echo
'a::test() exists!';
        else
            echo
'a::test() doesn\'t exists';

    }

   
    function
test() {
       
        return
true;
   
    }

}

$b = new a();

?>

the output will be: a::test() exists!

maybe this will help someone
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0
Anonymous
4 years ago
If you want to check in a class itself if a method is known you may do so with magic variable __CLASS__

<?php

class A{
 
__construct($method){
      return
method_exists(__CLASS__,$method);
  }

  private function
foo(){
 
  }
}

$test = new A('foo');
//should return true

?>

You might also use the method describe below with <?php in_array() ?> trick but I consider this one here easier and more readable and well, the way it is intended toi be done ;)
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0
seufert at gmail dot com
8 years ago
Just a note that the behaviour of this function changed between version 5.0.x and 5.1.x when using static member functions

Using this code:
<?php
class a {
    static function
test() {return "A";}
}
if(
method_exists('a','test'))
    print
call_user_func(array('a','test'));
else
    print
"Nothing";
?>
PHP 5.1.x returns "A"
PHP 5.0.x returns "Nothing"

Im not sure of a workaround for PHP 5.0.x yet.
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0
spam at majiclab dot com
8 years ago
Both method_exists() and is_callable() return private and protected functions, which, as mentioned below, causes problems for PHP5/OO programming.  You can use get_class_methods() with either an $instance of a class or the 'ClassName' to get only public functions.
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0
jpgiot at nospam ifrance.com
10 years ago
a little difference :

to find a method of an object (instance of a class)

<?php
if (method_exists($myinstance,'themethod'))
    echo
'ok';
?>

to find a method of a class (using the class name, not the instance of the class!)

<?php
if (is_callable(array('theclassname','themethod')))
    echo
'ok';
?>
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0
Thomas@ThBeckmann
11 years ago
Though, as Bejamin noted, it's not possible to use the class name in method_exists within the class definition, get_class_methods delivers the method names for a given class name even inside the class. Thus another workaround for the mentioned problem is to use in_array(<method_name>, get_class_methods(<class_name>))
up
0
j dot metzger at steptown dot com
12 years ago
call_user_method uses the same mechanism as a normal method call. So you can get the returned values as well in this way.

$pagetext=call_user_method($method,$object_call);

All information is then in $pagetext.
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