CascadiaPHP 2024

interface_exists

(PHP 5 >= 5.0.2, PHP 7, PHP 8)

interface_exists检查接口是否已被定义

说明

interface_exists(string $interface, bool $autoload = true): bool

检查接口是否已被定义。

参数

interface

接口名。

autoload

如果尚未加载,是否自动加载

返回值

本函数在由 interface 给出的接口已定义时返回 true,否则返回 false

示例

示例 #1 interface_exists() 示例

<?php
// 在尝试使用前先检查接口是否存在
if (interface_exists('MyInterface')) {
class
MyClass implements MyInterface
{
// Methods
}
}

?>

参见

add a note

User Contributed Notes 4 notes

up
6
CoR
8 years ago
Class and Interface share SAME namespace!

class k{}

interface k {} // Fatal error: Cannot redeclare class k
up
4
nils dot rocine at gmail dot com
12 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);
?>
up
4
andrey at php dot net
19 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.
up
1
maxim at inbox dot ru
11 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.
To Top