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 — Verifica se a interface foi definida
Descrição
Verifica se a interface foi definida.
Parâmetros
-
interface -
O nome da interface.
-
autoload -
Se deve-se carregar automaticamente a interface se já não tiver sido carregada.
Valor Retornado
Retorna true se a interface fornecida pelo parâmetro
interface já foi definida, false caso contrário.
Exemplos
Exemplo #1 Exemplo de interface_exists()
<?php
// Verifica se a interface existe antes de tentar usá-la
if (interface_exists('MyInterface')) {
class MyClass implements MyInterface
{
// Métodos
}
}
?>Veja Também
- get_declared_interfaces() - Retorna um array com todas as interfaces declaradas
- class_implements() - Retorna as interfaces que são implementadas pela classe ou interface fornecida
- class_exists() - Verifica se uma classe foi definida
- enum_exists() - Verifica se uma enumeração foi definida
add a note
User Contributed Notes 4 notes
CoR ¶
9 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.
