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)
interface_exists — 인터페이스가 정의되었는지 확인
설명
bool interface_exists
( string
$interface_name
[, bool $autoload = true
] )주어진 인터페이스가 정의되었는지 확인합니다.
반환값
주어진 interface_name이 정의되었으면 TRUE, 아니면
FALSE를 반환합니다.
예제
Example #1 interface_exists() 예제
<?php
// 사용하기 전에 인터페이스가 존재하는지 확인
if (interface_exists('MyInterface')) {
class MyClass implements MyInterface
{
// 메쏘드
}
}
?>
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.
