Class and Interface share SAME namespace!
class k{}
interface k {} // Fatal error: Cannot redeclare class k
interface_exists
(PHP 5 >= 5.0.2, PHP 7, PHP 8)
interface_exists — Comprueba si una interfaz ha sido definida
Descripción
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
- get_declared_interfaces() - Devuelve un array con todas las interfaces declaradas
- class_implements() - Devuelve las interfaces que son implementadas por la clase o interfaz dadas
- class_exists() - Verifica si la clase ha sido definida
add a note
User Contributed Notes 4 notes
CoR ¶
8 years ago
andrey at php dot net ¶
20 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.
nils dot rocine at gmail dot com ¶
13 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);
?>
maxim at inbox dot ru ¶
12 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.
