is_callable

(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)

is_callable — 检测参数是否为合法的可调用结构

说明

is_callable ( callable $name , bool $syntax_only = false , string &$callable_name = ? ) : bool

验证变量的内容能否作为函数调用。这可以检查包含有效函数名的变量，或者一个数组，包含了正确编码的对象以及函数名。

参数

name: 要检查的回调函数。
syntax_only: 如果设置为 true，这个函数仅仅验证 name 可能是函数或方法。它仅仅拒绝非字符，或者未包含能用于回调函数的有效结构。有效的应该包含两个元素，第一个是一个对象或者字符，第二个元素是个字符。
callable_name: 接受"可调用的名称"。下面的例子是"someClass::someMethod"。注意，尽管 someClass::SomeMethod() 的含义是可调用的静态方法，但例子的情况并不是这样的。

返回值

如果 name 可调用则返回 true，否则返回 false。

范例

Example #1 is_callable() 例子


<?php
//  How to check a variable to see if it can be called
//  as a function.

//
//  Simple variable containing a function
//

function someFunction() 
{
}

$functionVariable = 'someFunction';

var_dump(is_callable($functionVariable, false, $callable_name));  // bool(true)

echo $callable_name, "\n";  // someFunction

//
//  Array containing a method
//

class someClass {

  function someMethod() 
  {
  }

}

$anObject = new someClass();

$methodVariable = array($anObject, 'someMethod');

var_dump(is_callable($methodVariable, true, $callable_name));  //  bool(true)

echo $callable_name, "\n";  //  someClass::someMethod

?>

参见

function_exists() - 如果给定的函数已经被定义就返回 true
method_exists() - 检查类的方法是否存在

User Contributed Notes

mohamed dot elidrissi at protonmail dot com 28-Jun-2021 12:26


Note that -- as mentioned in the migration guide-- starting from PHP 8.0, is_callable() will not work with non-static methods if you use a class name, instead an object of the class should be provided:



<?php



class Test

{

    public function method1() { }

    public static function method2() { }

}



// Pre PHP 8

var_dump(is_callable(array('Test', 'method1'))); // bool(true)

var_dump(is_callable(array('Test', 'method2'))); // bool(true)



// Post PHP 8

var_dump(is_callable(array('Test', 'method1'))); // bool(false)

var_dump(is_callable(array('Test', 'method2'))); // bool(true)

var_dump(is_callable(array(new Test, 'method1'))); // bool(true)



?>

jlh 22-Mar-2019 09:28


The story about __call() is a bit more complicated unfortunately. It will always return true ONLY if you pass an instance of a class, not if you pass the class name itself:



<?php

class MyClass {

    public function method() { }

    public function __call($name, $arguments) { }

}



is_callable([MyClass::class, 'method']); // true

is_callable([new MyClass(), 'method']); // true

is_callable([MyClass::class, 'other']); // false!!!

is_callable([new MyClass(), 'other'])); // true

izharaazmi at gmail dot com 11-Jan-2016 06:50


If the target class has __call() magic function implemented, then is_callable will ALWAYS return TRUE for whatever method you call it.

is_callable does not evaluate your internal logic inside __call() implementation (and this is for good).

Therefore every method name is callable for such classes.



Hence it is WRONG to say (as someone said):

...is_callable will correctly determine the existence of methods made with __call...



Example:

<?php

class TestCallable

{

    public function testing()

    {

          return "I am called.";

    }



    public function __call($name, $args)

    {

        if($name == 'testingOther') 

        {

                return call_user_func_array(array($this, 'testing'), $args);

        }

    }

}



$t = new TestCallable();

echo $t->testing();      // Output: I am called.

echo $t->testingOther(); // Output: I am called.

echo $t->working();      // Output: (null)



echo is_callable(array($t, 'testing'));       // Output: TRUE

echo is_callable(array($t, 'testingOther'));  // Output: TRUE

echo is_callable(array($t, 'working'));       // Output: TRUE, expected: FALSE

?>

fgm at osinet dot fr 27-Jun-2011 05:03


Note that, for the purpose of this function, an abstract method, although necessarily non-callable since it does not have a body, is still considered to be callable:



<?php

abstract class Foo { 

  abstract function bar(); 

}



echo is_callable(array('Foo', 'bar'));

// display: 1

?>

rahadotaboulfethatgmail.com 01-Mar-2008 04:44


is_callable generates an [E_STRICT] error if the  tested method cannot be called staticly. (and returns the good value)



I used @is_called 

i'm using php 5.2.1

Quis strrev TA omicidio strrev TOD com 13-Nov-2007 03:50


is_callable() does _not_ check wheter this function is disabled by php.ini's disable_functions



use:



<?PHP

function is_disabled($function) {

  $disabled_functions=explode(',',ini_get('disable_functions'));

  return in_array($function, $disabled_functions);

}

?>



I`m running PHP 5.2.4