PHP Unconference Europe 2015

interface_exists

(PHP 5 >= 5.0.2)

interface_existsComprueba si una interfaz ha sido definida

Descripción

bool interface_exists ( string $interface_name [, bool $autoload = true ] )

Comprueba si la interfaz dada ha sido definida.

Parámetros

interface_name

El nombre de la interfaz

autoload

Si llamar a __autoload o no por defecto.

Valores devueltos

Devuelve TRUE si la interfaz dada por interface_name ha sido definida, FALSE si no.

Ejemplos

Ejemplo #1 Ejemplo de interface_exists()

<?php
// Comprobar si la interfaz existe antes de intentar usarla
if (interface_exists('MiInterfaz')) {
    class 
MiClase implements MiInterfaz
    
{
        
// Métodos
    
}
}

?>

Ver también

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User Contributed Notes 3 notes

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0
maxim at inbox dot ru
2 years ago
If you want to check for included interface and you already register spl autoloader - it will crash. Becassue autoloader trying to load `string` and he doesnt matter is it class or not.
Iv found several ways :
1 - unregister AL - -> check for Ifaces - -> register Autoloader

2 - $ifaces = array_flip(get_declared_interfaces());
if($ifaces["MyIface"]) // empty // isset .

Interfaces are not bad, you can build correct geomentry of system , with validation by funcs / vars / const .
Also they are good to storage variables <?php
ROOT
::THEMES ; ROOT::LOC ; ?> . Much faster then Define, but you cant put algorithms inside, only complite strings / __file__ / etc.
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0
nils dot rocine at gmail dot com
3 years ago
A little note on namespaces that may be obvious to some, but was not obvious to me.

Although you can make the below statement when the statement is in the same namespace as the interface/class declaration MyInterface...
<?php
$foo
instanceof MyInterface
?>

Making use of the interface_exists, or class_exists functions, you must enter the full namespaced interface name like so (even if the function call is from the same namespace.)
<?php
interface_exists
(__NAMESPACE__ . '\MyInterface', false);
?>
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0
andrey at php dot net
10 years ago
As far as I remember interface_exists() was added in 5.0.2 . In 5.0.0 and 5.0.1 class_exists() used to return TRUE when asked for a existing interface. Starting 5.0.2 class_exists() doesn't do that anymore.
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